Mini split installation for a house

[Zachary Hoyt]

I've been waiting for months for someone who is supposedly going to install a mini split, and today when he returned my last call he said that he would be getting a quote to me soon, but it would be higher than the $2-3k range he had guessed at an earlier time. He doesn't design the systems, just installs them. I'm thinking more seriously about doing it myself instead. The plan is to install it on the ground floor, which is open, 15' wide and 31 feet long for the kitchen and living room. There is also an added guest bedroom on one side but I am not worried about that for now. The whole house has closed cell spray foam now that the addition got done, so we're pretty well sealed.

We are planning to use a mini split for heat in spring and fall, but when the temperature outside goes below freezing we'll use the wood stove, which is working fine and seems like it would be able to heat the whole house even in cold spells. So far we've only had to have a fire a few hours a day, even with lows in the mid 20s. The mini split would have to be able to survive to -40 but we wouldn't be using it when it's cold. I'm looking at some kits that say they are DIY, like Mr Cool, which I have heard folks on here speak highly of. I'm also wondering how hard it would be for a non-HVAC person like me to buy or rent a vacuum pump and learn to do the lines myself. It seems like there are a lot more mini-split options if I was able to do that. I'll be grateful for any advice.

[Kris Cook]

I bought two units a couple of years ago and kept putting off professional installation until I had them both ready to fire up. I wanted to take advantage of a professional install to maintain the 7 year warranty. I realized I was already 2 years into the warranty period with no benefit of the units. Bit the bullet earlier this summer and installed the one in the shop by myself. It was pretty easy. If you are looking at a single-zone system then it is pretty straight-forward. I don't know anything about multiple-zone systems but can't imagine it would be that complicated. The units I purchased are Daikin they came pre-charged and I believe the charge is good up to about 25 ft. of line set if I remember correctly. If going beyond the pre-charged length you would have to add refrigerant which complicates things, I believe.

Anyway, I got the pump and gages for less than $200 (the same set is not $146 on Amazon). I also bought an eccentric flaring tool and a set of crow's feet so I could use my standard torque wrench. I can share the components if you are interested.

There are others on here with more experience and hopefully they will chime in.

[Zachary Hoyt]

Thank you, that's great to know that it worked for you. Good for you for getting it done. The deeper I dig into this the more I'm confused about which "DIY" kits require a pump and such, and how to tell them from the ones that don't.

[Tom M King]

You need a vacuum pump to evacuate the lines, I expect even with the precharged units, but I have no experience with them, so really don't know.

The system operates under high pressure, so the flare fittings are critical. Even pros have trouble with them leaking. Use these: https://www.amazon.com/dp/B07M81FBF9/?coliid=I7N4AJL9AAGP9&colid=2P8GBP5SU4LS7&psc=1&ref_=lv_ov_lig_dp_it

and torque the fittings properly with a flare nut crows foot on a torque wrench.

Even with a vacuum pump to evacuate the system, and a pressure gauge to see if it's holding vacuum, I still don't want to put refrigerant in a system without pressure testing it first with Nitrogen. No refrigerant should be released into the atmosphere, and guesswork has a high probability of that as a result.

It takes a grand or two to get set up good to work on HVAC systems, and you can easily spend way more.

I do business with, and recommend: Supplyhouse.com and Trutechtools.com

[Bill George]

As a guy who worked in the commercial HVAC/R field and then after being retired for a few years and installed my own Mini Split HP. My son who is still in the business recommends Mitsubishi as that is what his commercial Co used and had next to zero issues. Made in Japan all mini splits are not the same quality.

#1 Buy a good flaring tool, I used Rol Aire as I used for many, many years to make a leakproof flare on the first try and they make the flare with a segmented flaring cone above the flaring bar and then also polishes it, the tool is expensive!

#2 Since the flares are subject to cold and hot use either Leak Lock or Blue Loctite behind the flare nut and on the threads... it stops the loosing of the flare.

#3 Use a torque wrench, I never did but I have been doing this for over 30 years.

#4. Leak check first with either dry nitrogen or refrigerant that does not require recovery, I used a tank of R134a for pressure. Think, if you pull a vacuum before pressure checking, your just sucking in air and moisture in from any leak. Vacuum leak checking is only at 14.7 psig, think why?

#5 Use a good vacuum pump to pull down to at least 500 microns.

#6 Open those service valves slowly and you do have gauges for R410a? Recheck those fittings again.

#7 I did have a minor leak on the liquid line I needed to repair, but all is fine now. Works down to say -12 or so heating very low energy costs! This is going to be my 4th heating season.

[Maurice Mcmurry]

If you can make stock line sets work you can skip DIY flaring and avoid potential problems. Pioneer caters to DIY but there is a "Certified Installer" line on the warrantee form. Pulling a vacuum can also be bypassed with a line flushing kit. I think a deep vacuum that holds for a day or two is the best leak test.

[Jim Becker]

Mr Cool DIY systems can be installed without a vacuum pump as the line-sets are pre charged. The current range is broad and multi-air handler units are available which is typically what you want for a home. I'll be using one of these units in my new shop building, but likely with just a single air handler since it's an open space. (Buying mine through Costco)

Do note that many mini splits available today can handle outside temps down to as much as -5º F. Check the specifications if that's important to you.

[Zachary Hoyt]

Thank you all for the advice. Jim Becker, I think that the house here is more analogous to a typical workshop in some ways, since it's an open rectangular area that we want to heat and cool, and the bedrooms can take care of themselves at least for now. It's not important to me to be able to use a mini-split at -5, as I imagine the stove will keep up with that if we keep it stoked steadily, but I haven't found much information about what temps the outside unit can withstand without a problem, and it can get pretty cold here at times.

[Ronald Blue]

I put two Mr Cool mini splits in my shop this summer. Home Depot was the best price and almost immediate availability. I think they were in store in three days. Mine weren't DIY as far as the lines weren't pre-charged. I had my local HVAC guy assist and when we were finished it was about $500 for his labor. He recommended Mr Cool. The price is definitely competitive. Ther were $1,100+ each. They worked great as cooling units. I have radiant floor heat for cold weather. They also have ducted mini splits as I understand it. I can look at the manual and see what temperature range it lists.

[Bill George]

For a system that runs 400 plus psig on the high side, leak testing should be done at pressures 300 psig or more. Dry nitrogen is best because it is stable temperature wise and much cheaper and legal compared to refrigerant.

Removing all the air and then down into a deep vacuum means you pressure checked at 15 (14.7) psig Which is better?


BTW my Mitsubishi Hi HP works and heats down to -12 and the compressor, outside and inside fan motors all modulate speeds according to the load.

[Tom M King]

There are cheap nitrogen regulators, but I bought a good one. Buying a filled 40 cu. ft. tank cost $140. Refilling it costs a few cents less than $25. Now that I own the rig, I can pressure test as much as I want to, and purge the inside of the lines if I want to braze. Total rig cost cheaper than one service call around here.

This is the regulator I bought, and it works like a charm. You can buy cheaper ones, but the reviews don't sound so great.

https://www.trutechtools.com/victor-model-ess32-pfh-580-edge-series-2.0-heavy-dutymedium-capacity-pressure-flow-hybrid-nitrogen-single-stage-regulator-cga-580.html

[Jim Becker]

Thank you all for the advice. Jim Becker, I think that the house here is more analogous to a typical workshop in some ways, since it's an open rectangular area that we want to heat and cool, and the bedrooms can take care of themselves at least for now. It's not important to me to be able to use a mini-split at -5, as I imagine the stove will keep up with that if we keep it stoked steadily, but I haven't found much information about what temps the outside unit can withstand without a problem, and it can get pretty cold here at times.

I think you'll be pleased with the performance. The temperature floor should be in a unit's specifications, but having the woodstove is certainly a boon for when things are blowin' up there in the sticks. :) With the house being somewhat open as you describe, the simpler units should work fine. A 24K BTU unit covers up to about 1000 square feet, and with good insulation and infiltration sealing, things can be pretty comfortable. If you are doing through-floor vents so your woodstove heat can circulate upstairs, you will likely get similar benefit with the split when using it. Going with the mini split also gives you AC, so that's a win-win, IMHO. You may not need it as often as farther south, but it will cover "those times" when things get sticky and that's unfortunately very likely to be more frequently going into the future.

[Bill George]

Just about any Nitrogen regulator would work fine.

I did some reading on the Mr. Cool units seem like a decent HP but it looks like they are Made in China so time will tell.

One issue is the pre-charged line sets, my experience in running service years ago when the DIY AC units were sold at home improvement stores, the homeowner would install and screw up the install and they leaked. So we were called by the irate homeowner who did not understand since he screwed it up, he had to pay! The Warranty did not cover either, and we did not get paid. That was the end of doing DIY service calls for homeowners.

My personal opinion, flare fittings have no business on high pressure R-410a, we either silver brazed or Sil Phos brazed those fittings. with Nitrogen purge to prevent the copper oxide scale from forming on the inside.

There is now in the future a phase out of R410a and the replacement is flammable.

Try buying R410a to top off your unit when its been leaking.

[Jack Frederick]

I use Fujitsu minis. I was the factory rep in the six New England States for 14 yrs and saw, well, a lot. The vast majority f mini problems are poor flares. In heat mode you are pushing 6-800 psi and it is in heat that problems show. Absolutely use the nitrogen purge. It will show your flare issues if there are any and you want to be absolutely certain they are right before you release the refrigerant. When making up the flares wipe a finger wetted with your vac pump oil on the face of the flare. Just moisten it a bit. I had people send units back to Fujitsu and if there was leak lock or any type of dope on the threads they would refuse warranty out of hand. I would never use factory flares on a line set. Line set manuf could care less of a system leaks. They flare the lines only to hold the plastic shipping plug in place. I use a Hillmar flaring tool. I have the Yellow Jacket unit but found a couple leaks with it as the 1/4” tubing slipped. Cut a few feet of line set and practice flaring it until you are comfortable. DO NOT put the condensing unit on a pad outside. Having grown up Upstate as I recall it gets cold and actually snows. It is disappointing when the condensing unit turns into an ice cube. Either use one of the wall mount kits or a high standoff on the pad. I have seen frost heave about turn these things over, so… Set it level and keep it there. Elevating keeps it clean as well. Should you be tempted to braze the line sets use the nitrogen or you will sugar that line set. Also it doesn’t take a lot to plug a 1/4” tube. Mitsu and Fujitsu are one/two in the US. I won’t touch a Daikin as they pissed me off back in ‘84. Living in Orwell i would only go for the low temp units. You need to research the lines you are interested in and make sure you understand the specs on each model within a manuf line up. it is complicated so make sure you understand what you are buying. Oh, and the drain. I find it really difficult to close the unit onto the mounting bracket with the power line, insulated line set and the flexible drain. it is the classic 5# in a 4# bag. Most manuf I believe let you move the drain connection to the left side. You can then run it directly. Trap moisture in a humid climate, yours, and you cannot believe how fast mold will grow.
If you are looking for a heating alternative I would suggest a Rinnai EX-22 LP or NG. Not inexpensive, but excellent. I introduced those in New England in ‘91 and have heated my homes, shop, garages and basement with them since. I’m sitting about 8’ from one now. The minis are on the other side of the house and upstairs. They are an excellent companion to minis, a simple install and bullet proof.

[Bill George]

Jack I agree 100% Except for the blue Locktite on the threads only, Never any on the flare face. Having worked commercial refrigeration service for years I always found the leaks on TEV flare nuts in the cooler case or WI cooler, a little on those threads, (expansion and contraction) Never on the flare face and we did not have call backs. Those flared line sets were fine for R22 but really should be redone as you describe for the high pressure R410a.

[Zachary Hoyt]

Thank you all very much for the advice. I'm about as confused as I was before, but now I know more about what I'm confused about, so that's a step in the right direction.

[Bill George]

Thank you all very much for the advice. I'm about as confused as I was before, but now I know more about what I'm confused about, so that's a step in the right direction.

If your going to DIY and are good with details and have mechanical / electrical skills assuming the reviews are good the Mr. Cool looks to be decent. I see Amazon is selling check on there.

[Tom M King]

check Supplyhouse too.

[Thomas Pender]

Put a Mitsubishi mini-spit into the garage part of our lower level where I have my shop - perhaps 1400 SF. I did not do it. I had the local pros who maintain my heat pump do it. It was put in under almost ideal conditions - close to the 400 A circuit boxes, good access for the lines, good place for the condenser, etc. Based upon my previous HVAC experience, which is significant, this is not a job for anyone other than certified techs, so this is something I may disagree with others about. We have a saying, a bad install can ruin a great system or the HVAC is only as good as the installer. Have to be honest - it was not cheap - around 6K, but it has a 10 year warranty, is as quiet as a church mouse, and the work outside through the brick looks terrific, plus even with my experience, this was not something I was going to do when you see the need for double lines, wiring, and the condensate line. These guys had done many of these and they did a super job and they told me if I wanted another inside unit, the outside unit could carry it. My wife was a bit grouchy about it, but part of the upper floor will be warmer (the front of the house is 13’ higher that the back where the second driveway and what used to be a 4 car garage is - it is a shop now) and she is fond of that thought. Critical thing for me is humidity control in the summer (has a drying function) so I can dry lacquer and varnish and apply finishes and work more safely in the winter.

[Jack Frederick]

Bill, with respect, I was reluctant to challenge your experience. Why, well because I don’t have it;) I’m not sure how other manuf will handle it but Fujitsu, while an excellent line had hard and fast rules on any type of dope on the unit connections.

[Bill George]

Bill, with respect, I was reluctant to challenge your experience. Why, well because I don’t have it;) I’m not sure how other manuf will handle it but Fujitsu, while an excellent line had hard and fast rules on any type of dope on the unit connections.

Never any pipe dope, where did you see me post that??

Blue Locktite ON THE THREADS ONLY. The flare seals on the copper face of the tubing and to the brass face of the fitting, NOT the Threads! The Blue Locktite keeps the nut from backing off the fitting due to heat pump temperature change. The larger gas line is either the Cold suction line in the AC mode or Hot gas line in the Heating mode. Never pipe dope on flare fittings!! Locktite is for thread locking Only!!

For folks who don't read the entire Thread, here is a copy and paste of what I posted:
Jack I agree 100% Except for the blue Locktite on the threads only, Never any on the flare face. Having worked commercial refrigeration service for years I always found the leaks on TEV flare nuts in the cooler case or WI cooler, a little on those threads, (expansion and contraction) Never on the flare face and we did not have call backs. Those flared line sets were fine for R22 but really should be redone as you describe for the high pressure R410a.

[Michael Drew]

I've been waiting for months for someone who is supposedly going to install a mini split, and today when he returned my last call he said that he would be getting a quote to me soon, but it would be higher than the $2-3k range he had guessed at an earlier time. He doesn't design the systems, just installs them. I'm thinking more seriously about doing it myself instead. The plan is to install it on the ground floor, which is open, 15' wide and 31 feet long for the kitchen and living room. There is also an added guest bedroom on one side but I am not worried about that for now. The whole house has closed cell spray foam now that the addition got done, so we're pretty well sealed.

We are planning to use a mini split for heat in spring and fall, but when the temperature outside goes below freezing we'll use the wood stove, which is working fine and seems like it would be able to heat the whole house even in cold spells. So far we've only had to have a fire a few hours a day, even with lows in the mid 20s. The mini split would have to be able to survive to -40 but we wouldn't be using it when it's cold. I'm looking at some kits that say they are DIY, like Mr Cool, which I have heard folks on here speak highly of. I'm also wondering how hard it would be for a non-HVAC person like me to buy or rent a vacuum pump and learn to do the lines myself. It seems like there are a lot more mini-split options if I was able to do that. I'll be grateful for any advice.

I have no experience or brilliant suggestions to offer, but you might find a couple episodes on YouTube helpful. I watched the entire series, and learned quite a bit (I am a self taught framer/builder). He installed a split system in a spec house he was building. He did not go into the minutia, but you'll at minimum, get to see the system installed and know what you are getting into if you DIY. Episode #34 is where they start installing duct work in the crawl space. 107 they start the split system install. https://www.youtube.com/playlist?list=PLRZePj70B4IwyNn1ABhJWmBPeX1hGhyLi

[Bill Dufour]

I had to buy an adapter, under $10, to hook up pump and gauge set to weird metric? small size gauge port. Unlike big units the two lines get run together there is not a hot and cold line. I ran mine outside in 3" PVC conduit with foam sleeve around both at the same time.
I used my car ac gauge set, just make sure the high pressure gauge goes high enough. Note that ac tube is named different from water tube. one is outer diameter the other is inner diameter for the identical item.
It has to be an electric pump, a water venturi is not enough. The pump does not have to be much horsepower. Low power is cheaper and just slower. I bought mine used, just check and use the correct oil. It is not compressor oil. I prefer to leave it under vacuum overnight for good measure.
Bill D.

https://www.amazon.com/Adapters-Refrigerant-Adapter-Converter-Connectors/dp/B09W8VV1DC/ref=sr_1_2_sspa?keywords=mini+split+adapter&qid=1667261288&qu=eyJxc2MiOiI0LjQ1IiwicXNhIjoiNC4xNyIsInFzcCI6IjQ uMDQifQ%3D%3D&sr=8-2-spons&psc=1

[Michael Schuch]

I installed a single head 12000btu Fujitsu mini-split in my great room myself about 6 years ago. It was disgustingly easy! 2 years ago I installed a Mitsubishi 3 head mini split for the bedrooms (6000, 6000 and 9000btu's). It was a bit more challenging but very doable.

3 weekends ago I helped a friend who is just starting his DIY career install a 9000btu Mitsubishi in a shed that he built himself from a kit and then transformed into his home office. He had NO CLUE about HVAC! I showed him how to flare the ends with the good Yellow Jacket eccentric flaring tool (~$150). Then showed him where the maintenance port on his condenser was and explained the function. He really did the whole install himself with me just watching. We DID charge his lines with 400psi of nitrogen and let it sit for 24hrs to test for leaks.

The equipment I own for mini-split installs is:
1) 2 stage vacuum pump. I went for one with really good ratings but not a name brand... and a bottle of vacuum pump oil (the oil evaporates as near complete vacuum so the oil is consumable).
2) Yellow Jacket gauge and hose set used off of EBAY. There are $0.10 seals that I had to replace on the ends of all the hoses... these are a consumable item in the industry.
3) Nitrogen Tank (It was $30 more to buy one that it was to rent one).
4) Pressure gauge for the nitrogen tank that goes up to 500psi and a special fitting to connect to the AC gauge set.
5) Yellow jacket eccentric flaring tool. New on Amazon for ~$150 (a little less I believe).
6) Tube of NyLoc. about $5

My friend was disgusted with how easy the whole install was! What the HVAC guys charge is outrageous!

From your description it sounds like a 12000 btu unit should work well for you... especially with the sprayed closed cell foam insulation. I was really tempted to get a 15000 btu unit for my great room but contained my natural tendency to over build and stayed with the 12000 but unit. It works perfectly and is more efficient than if I had gotten the 15000 btu unit. The particular Fujitsu 12000 btu compressor I bought has a heating element on it that keeps the coils free of ice. It has provided enough heat in our great room down to -20F. My great room is not well insulated with lots of windows and 3 single pane skylights. I have heated floor in my great room which I keep at about 55degrees during the winter to keep our feet warm.

My copper lines came with insulation around each line AND I covered each insulated line with pipe insulation from HD. I needed the 4" PVC line cover to fit the twice insulated pipes in.

Flaring tool:
https://www.amazon.com/gp/product/B007PBCYOM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Vacuum pump:
https://www.amazon.com/gp/product/B01N0SYCL4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Vacuum oil:
https://www.amazon.com/gp/product/B008PKWHNK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Nitrogen tank gauge:
https://www.amazon.com/gp/product/B07CWKSBWW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Replacement gaskets for my hose/gauge set because I bought a used set!
https://www.amazon.com/gp/product/B00E549YWW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

[Bill Dufour]

For the tube runs inside the wall I used the foam swim noodles from the dollar store for insulation. No slits to ever open up. I also used them as guides to run the flex drill inside the wall to drill through the floor plate. I filled the wall cavity with vermiculite insulation after the tubing was run.
The swim noddles come in two diameters, different prices, so make sure the inner hole is big enough and the outside is mall enough it will fit in the stud cavity.
Bill D

[Bill George]

I had to buy an adapter, under $10, to hook up pump and gauge set to weird metric? small size gauge port. Unlike big units the two lines get run together there is not a hot and cold line. I ran mine outside in 3" PVC conduit with foam sleeve around both at the same time.
I used my car ac gauge set, just make sure the high pressure gauge goes high enough. Note that ac tube is named different from water tube. one is outer diameter the other is inner diameter for the identical item.
It has to be an electric pump, a water venturi is not enough. The pump does not have to be much horsepower. Low power is cheaper and just slower. I bought mine used, just check and use the correct oil. It is not compressor oil. I prefer to leave it under vacuum overnight for good measure.
Bill D.

https://www.amazon.com/Adapters-Refrigerant-Adapter-Converter-Connectors/dp/B09W8VV1DC/ref=sr_1_2_sspa?keywords=mini+split+adapter&qid=1667261288&qu=eyJxc2MiOiI0LjQ1IiwicXNhIjoiNC4xNyIsInFzcCI6IjQ uMDQifQ%3D%3D&sr=8-2-spons&psc=1

Bill can you tell the brand name and model number of the unit you put in? Been working with HVAC/R for over 30 years, never heard or worked on a unit that the lines don't get cold for AC or Hot in the heating mode?? My Mitsubishi unit came with standard 1/4 inch flare service ports.

[Bill Dufour]

Brand was Friedrich. One was cool only the other was cool and heat. The instructions ay to insulate the tubes together. Do not leave the high pressure line exposed under the house. This surprised me too.
I think it may be to cool the high pressure liquid before it gets to the evaporator.
Bill D

[Jack Frederick]

Friedrich doesn’t make their units. Back from mid-90’s -about ‘09 they private labeled Fujitsu’s, but Fujitsu always gave them the “last” model rather than the front line models. I don’t recall who they went to after that.

[Bill George]

Brand was Friedrich. One was cool only the other was cool and heat. The instructions ay to insulate the tubes together. Do not leave the high pressure line exposed under the house. This surprised me too.
I think it may be to cool the high pressure liquid before it gets to the evaporator.
Bill D

No wonder that unit does not have a high efficiency rating the object of the hot gas is to heat. It should be insulated and not ran with the cooler liquid line. The inside coil is either heating or cooling If you have a true heat pump.

[Bill Dufour]

They were higher efficiency then many and less then half the noise of many quality units. If you believe the numbers the makers publish. It is a good bit quieter then the mitsubishi units.
Bill D

[Zachary Hoyt]

Got a call this morning from the guy who was going to put in the mini split, saying his supplier had a preliminary materials list that came to $4800. I said that was more than I would be able to afford. If I remember correctly a couple of months ago he had mentioned $2k+ as the likely materials cost, so I was a bit surprised. I imagine this is a "don't want to do the job" quote. I have been looking at the 4th generation Mr Cool units like Jim Becker is buying for his shop, and they say they are able to heat down to -13(not that I want to anyway) and can be installed by a normal person with normal tools, so that all sounds pretty hopeful. I am thinking an 18k BTU unit might be right, given the smaller size of the house, and it looks like I could get a kit with everything for a bit over $2k or so from various suppliers. I'll just have to hope there are good instructions.

[Bill George]

Zach the Mitsubishi I put in had one of the highest SEER 24 AHRI Ratings on the market, if not the Highest. They are AHRI Certified not just advertising claims. It still uses Flare fittings I believe even now, but the unit has the complete charge contained. I ordered with the shortest line set, 15 ft long. Both lines insulated as they should be for a heat pump. Your guy is BSing you, most of those mini splits today come as a package you just need to get the correct line set.

My son got me a wholesale his company price and I am still CFC Certified to work with refrigerants so I had No issues getting the $300 Rebate after they inspected the install and got the AHRI number off the nameplate.

I looked at one of those Mr. Cool install videos and they do a good job of showing you what to do and even leak checking... and they are using insulation on Both the lines as they should for a heat pump.

[Zachary Hoyt]

I don't understand SEER enough to know how much difference there is between the unit I am looking at which is 22 SEER vs 24 that you mentioned. I watched a video too and it looks well within my ability, I think. Flaring is something I would just as soon not have to do, though it would doubtless come in handy again someday if I learned it now.

[Jim Becker]

Zackary, the Mr Cool 24K BTU unit I bought via Costco was $2299 plus tax with free shipping. I was expecting a couple of weeks, but delivery is scheduled for next Tuesday. The single head 18K BTU unit is $1899 plus tax and the two head 18L BTU unit is $2799 plus tax. No vacuum pump is required...just electrical and a few other odds and ends are needed to complete the install.

[Lawrence Duckworth]

I don't understand enough to know how much difference there is between the unit I am looking at which is 22 SEER vs 24

zach.....the difference between 22 and 24 is 2 :D

[Jim Becker]

I don't understand SEER enough to know how much difference there is between the unit I am looking at which is 22 SEER vs 24 that you mentioned.

24 SEER is slightly more efficient for cooling than 22 SEER, but these units are "way up there" in efficiency compared to most traditional HVAC systems. For where you live, the "cold temp limit" is probably more important if you are comparing two or more options, honestly.

[Zachary Hoyt]

I do have a general understanding of the concept of 2, most days, but I don't know if the scale works like decibels do, or is a more conventional system. I can't even remember the right words to describe these systems.

I don't plan to use the mini split in sustained sub-freezing weather, as the wood stove is well able to heat the house. I haven't been able to find any information about how cold of a temperature they can withstand while just sitting there idle, but I imagine if one can keep making heat down to -5 it would probably be able to survive without damage even down to -30 or -40 on rare occasions.

Thank you Jim for posting the prices. I'm not a Costco member, but I'll have to look into what it would cost to join, and if that would be cheaper than buying one elsewhere. I'd also need to get the wall mount bracket for the outside unit.

I am still a bit confused about what size to buy. The main part of the ground floor is a bit under 500 square feet, but with 9 foot ceilings and several large windows. It is also very well insulated as the whole house is now spray foamed. I don't plan to use the mini split in really cold weather, and our cooling load is not that high up here, where the nights are usually cool even in the middle of the summer due (I think) to the higher elevation. We rarely get many days over 90 in the summer. Some things I have been reading talk about the greater risk of undersizing the system, and some of oversizing. Based on the manufacturers recommendation we'd be somewhere between a 12k and an 18k unit depending how much of the house is considered. Counting the upstairs and the added bedroom we're still under 900 square feet, not counting attics, which are spray foamed but will be kept shut off most of the time.

Thank you all for your help, I really appreciate it. I'm hoping to get something ordered in the next week or so, and get it put in as soon as it arrives, weather permitting. Tomorrow morning is the final electrical inspection on the house and workshop, so I am a little nervous.

[Tom M King]

You don't have to do any flaring if you can make the stock length of the lineset work. If it runs under the house, you can just let it snake around some extra. If you're limited with how the lines have to run, an end may need to be flared.

You can get a Parker fitting that works much like a Sharkbite to adapt a cut line with a flare end. I haven't used the flare adapters, but have used couplings and elbows and am pretty impressed with them. I used them on a bad line in a rental house, but they may be as expensive as buying a good flare tool, but there are other options. I just didn't want to braze where I needed to use those fittings.

They are Really efficient. We cooled 7,000 sq. ft. with 18k btu this Summer for all but two days. Our house is super insulated. I had that unit put in for my Mother's Suite when she had to move in with us because I thought she would want her part warmer than we do, but she didn't. I did a bit of rearranging of ducts under the house so we can run fans only in other systems so it moves it around in a circle. So far, with a few nights down close to freezing, it's working well for heat too. I think it will serve us through the Winter because we have a gas heater we can add when it gets cold for long. It saved us over 200 a month this past Summer with no loss of comfort, and less noise.

With that in mind, 18 sounds like too much for 500 sq. ft. I think you could make ice in there in your Summertime, but they do adjust on their own really nicely, so you may make good use of the heat.

Check Supplyhouse for price too. They sell Mr. Cool, and have really knowledgeable people working there. Their stuff gets here the second day after I order it. I have a pro account there, which gives some discount and free shipping on any order regardless of size, but you have to be a building pro and have a website, and be approved.

[Bill Dufour]

The term you are seeking is logarithmic scale. I do not know if seer is that way or not. I know db sound is a log scale.
Bill <D

[Walter Mooney]

Zach, I bought a DIY Mr Cool unit from Costco after reading Mr. Becker’s recommendation. It was delivered in two boxes. The directions were great — clear, concise, and very easy to follow. I poured my own slab for the outdoor unit because I couldn’t get one anywhere close to my little shop in the TX Hill Country. Then the next day, installed the unit, with help from my son, and had it up and running before 2 PM! The biggest thing to be careful of is the connection of the two lines in the two different places. Be extra careful starting the threads, pay attention as you tighten them, and everything else is a piece of cake. I couldn’t be happier with my unit and the ease of installation. I’ve only used it for cooling thus far, but none the less, I am a very satisfied customer.

I thank Mr. Becker for his many ‘on-point’ posts. Good luck to you!

[Michael Schuch]

Oversizing a mini split kills its efficiency.

18,000 btu sounds too big for 500 sqft to me also. It will work and cool but it will run at a lower efficiency rating than advertised. Getting the right size unit is the key to efficiency. None if the HVAC guys I ever talked to ever calculated load (probably didn't know how to). They all pretty much shot from the hip... What do they care, they aren't going to pay your electric bill.

[Bill George]

I agree and a lot of HVAC guys are self taught and do not have a clue about load sizing. I learned the Manual J software heating and cooling load calculation and then taught the subject. However the Mini split I have adjusts to the load and the SEER rating more or less holds true. My heating and cooling costs for that area are very reasonable and with sizing don't forget the sun or solar load on the exposed glass.

The Mr. Cool seems to be a decent system IF you can follow directions and IF there are no issues.

[Dwayne Watt]

I do have a general understanding of the concept of 2, most days, but I don't know if the scale works like decibels do, or is a more conventional system. I can't even remember the right words to describe these systems.

I don't plan to use the mini split in sustained sub-freezing weather, as the wood stove is well able to heat the house. I haven't been able to find any information about how cold of a temperature they can withstand while just sitting there idle, but I imagine if one can keep making heat down to -5 it would probably be able to survive without damage even down to -30 or -40 on rare occasions.

Thank you Jim for posting the prices. I'm not a Costco member, but I'll have to look into what it would cost to join, and if that would be cheaper than buying one elsewhere. I'd also need to get the wall mount bracket for the outside unit.

I am still a bit confused about what size to buy. The main part of the ground floor is a bit under 500 square feet, but with 9 foot ceilings and several large windows. It is also very well insulated as the whole house is now spray foamed. I don't plan to use the mini split in really cold weather, and our cooling load is not that high up here, where the nights are usually cool even in the middle of the summer due (I think) to the higher elevation. We rarely get many days over 90 in the summer. Some things I have been reading talk about the greater risk of undersizing the system, and some of oversizing. Based on the manufacturers recommendation we'd be somewhere between a 12k and an 18k unit depending how much of the house is considered. Counting the upstairs and the added bedroom we're still under 900 square feet, not counting attics, which are spray foamed but will be kept shut off most of the time.

Thank you all for your help, I really appreciate it. I'm hoping to get something ordered in the next week or so, and get it put in as soon as it arrives, weather permitting. Tomorrow morning is the final electrical inspection on the house and workshop, so I am a little nervous.

this calculator might help you understand your sizing needs: https://www.ecomfort.com/stories/1439-What-Size-Mini-Split-Should-You-Buy.html
The shortcoming of this estimator is not having a specification for wall or ceiling R-values.

[Jack Frederick]

It used to be that the rule of thumb for cooling was 400 sq ft/ton. One ton=12000 btu. In Orwell NY for a primarily cooling unit an 18 is almost double what you should get. Mind you, you get some buffer on sizing as the units modulate. My 12 k unit modulates from 3200-about 14000. Over sizing a cooling unit hurts the dehumidification operation which is what you need most in the NE. Folks will tend to go larger when sizing for heating. One thing to consider in picking the unit is that a Hyper-Heat model which can heat to those lower temps is invaluable when you are away and the stove is out. It can prevent freeze-ups…some. SEER is seasonal energy efficiency rating and is used for cooling efficiency. HSPF is Heating Seasonal Efficiency Rating. The thing is on the ratings they basically test them as a standard single stage unit negating all the benefits of the modulation. They do the same on AFUE on Gas heating. When the 410a inverter minis came out standard AC was 10 seer and the US manuf fought like hell to not have to meet the 13 seer gov’t requirement. In ‘06 I installed a Fujitsu in my home that was 24 seer and heated down to -5*. it was magic. In speaking with one of the Japanese engineers from Fujitsu he said that if they could actually test the units properly they would be coming in in the mid 30’s seer wise.
In your place Zack I would do a 12k unit for that primary space. You can use products like Tjernlund Products, Airshares to move air to other rooms or you can cut registers into walls high and low to encourage air flow. That works.

[Jim Becker]

Zachary, Costco "regular" membership is like $60 annually and "Executive" membership is $120.

The 18K BTU unit may very well do the job for you. If you have direct floor vents between the first and second floors, even better. But jack is correct that the 12k BTU unit would likely do well for just the primary space. The cost difference is only a few hundred and unlike traditional HVAC systems, mini splits tend to compensate better for "more than you need" because of their completely variable heating/cooling/airflow model.

[Zachary Hoyt]

Thank you all for the help. I'm thinking that a 12k would be the place to start, and if it turns out to be too small for the house I could (sometime next year when time and money permit) hire someone with the right equipment to capture the refrigerant so I could move the 12k to the workshop, and buy an 18k for the house. The workshop is 465 square feet, so I'm sure a 12k would be enough for it, even if it turned out not to be for the house. If the 12k is right for the house then (again when time and money permit) I could look into getting a 9k or something for the workshop building.

[Tom M King]

I installed a new line set for a heat pump in a rental house today using four of these couplings. The vapor line was leaking behind a brick wall. This makes the total number of these couplings I've used to 8, and not one has leaked. I was extra ocd about polishing the tubing ends before inserting them.

I've not used one of the flare adapters, but I would have no hesitation to use one, or even use the factory flare end, and a coupling if you need to cut a line. You can find Youtube videos about them.

https://ph.parker.com/us/en/zoomlock-push-optimized-for-r-410a

[Bill George]

I installed a new line set for a heat pump in a rental house today using four of these couplings. The vapor line was leaking behind a brick wall. This makes the total number of these couplings I've used to 8, and not one has leaked. I was extra ocd about polishing the tubing ends before inserting them.

I've not used one of the flare adapters, but I would have no hesitation to use one, or even use the factory flare end, and a coupling if you need to cut a line. You can find Youtube videos about them.

https://ph.parker.com/us/en/zoomlock-push-optimized-for-r-410a

Excellent. Now to connect to the unit Flare fittings and then to the Line where do you get those? Never mind it looks like I found the other ones, and all sold by my favorite supply house here in town. Wish I had shares in both those companies. Looks like you need to do some prep to the lines and thats Ok.

[Tom M King]

I ordered them from Supplyhouse. My local supplier in town had the Rectorseal versions in stock, but said they'd never sold one. I decided to go with the Parker ones that are a later generation that they claim is optimized for 410a. I have confidence in both Rectorseal and Parker products, but nod goes to Parker. Parker had a previous generation of these that had a good reputation, so I figured this latest generation should be even better.

It was so tight in that attic that I really didn't want to drag a torch up there to braze the lines with, so decided to try these. The first ones worked as advertised, so I just decided to go all with them rather than have to purge the lines and drag my torch rig over there. I don't have a small acetylene rig, but have used the big tanks on the cart for the cutting torch. I have to move that with the tractor, and it's more than a little trouble, especially to make sure the wheels on the cart are clean enough to roll in a house.

[Bill George]

I ordered them from Supplyhouse. My local supplier in town had the Rectorseal versions in stock, but said they'd never sold one. I decided to go with the Parker ones that are a later generation that they claim is optimized for 410a. I have confidence in both Rectorseal and Parker products, but nod goes to Parker.

It was so tight in that attic that I really didn't want to drag a torch up there to braze the lines with, so decided to try these. The first ones worked as advertised, so I just decided to go all with them rather than have to purge the lines and drag my torch rig over there. I don't have a small acetylene rig, but have used the big tanks on the cart for the cutting torch. I have to move that with the tractor, and it's more than a little trouble.

Both Parker Hannifin and Sporlan are old line trusted companies in the HVAC/R field. Rectorseal is plumbing related. I think if you can keep the Joe Sixpack folks from screwing up the install of these, and you must take the time to do the Prep otherwise they will fail and then get a bad reputation. Thanks for posting the good info.

[Tom M King]

They come with a piece of Maroon Scotchbrite pad to clean the end with in the install kit to mark insertion depth by. I used that, but followed with a gold, finer grade. I expect they work fine with just the Maroon one that they include, but I like it better with no scratches. They do say to go around only, so the scratches don't go in line with the tube, but I like no scratches. I also cleaned them with Acetone and lintfree cloth, and waited plenty of time for it to dry.

At first I thought the insertion depth thing was not necessary, as they go right on new tubing, but on the old tubing, even well cleaned as good, it took quite a bit of force, and I couldn't tell without the line when it was all the way home.

The Rectorseal, and I think the first generation of Parkers were removable, much like a Sharkbite. This latest Parker generation is not removable, and I can't think of why I would want to reuse one, or even subject the seals to going anything but one way.

Right on Rectorseal and Parker. I always trust Parker for pneumatic and hydraulic stuff, and Rectorseal for plumbing stuff.

[Tom M King]

Before I install another mini-split, I'm getting one of these. To me, balancing it on something while hooking up the inside unit is the worst part.

https://rectorseal.com/mighty-bracket/

As is usually the case, Supplyhouse seems to have the best price:
https://www.supplyhouse.com/Rectorseal-97705-Mighty-Bracket-Mini-Split-Installation-Support-Tool?utm_source=google_ad&utm_medium=Shopping_tm&utm_campaign=Shopping_TM_Returning_users&gclid=CjwKCAjw8JKbBhBYEiwAs3sxNy_osPi6evLSF49_Ud6f YYcGDBOH5Ic-HYE7HX-FsZPF7esy7vqPJxoCG5IQAvD_BwE

[Tom M King]

If you haven't bought a manifold set yet, I like a four valve so you can hook up a vacuum pump and the refrigerant tank at the same time, and completely evacuate even the last little bit of air out of all the lines.

Folding plastic tables save me a lot of bending over on all sorts of jobs.

[Bill George]

I purchased the Yellow Jacket brand manifold and the hoses it was like $250. My old, old set I used on the job is still hanging on the hook ready to use on my R134a car AC.

BTW on those Parker fittings, I would just use the scotch pad included and do the circular cleaning as instructed on the tube. To much polish and it might not grip as well?

[Tom M King]

They grip like a Beast. The grip teeth are metal. They aren't removable like the first generation that only needs a plastic C clip to release them. I keep a separate manifold for 134a too.

[Jack Frederick]

I have found that the mounting brackets have become lighter over the decades. It is no end of frustrating to do everything and finally set the evap on the bracket and the top corners pull away from the wall a bit. I’ve gotten stung by this a couple times so I always throw a toggle in at the upper corners of the mounting bracket.

[Michael Schuch]

Thank you all for the help. I'm thinking that a 12k would be the place to start, and if it turns out to be too small for the house I could (sometime next year when time and money permit) hire someone with the right equipment to capture the refrigerant so I could move the 12k to the workshop, and buy an 18k for the house. The workshop is 465 square feet, so I'm sure a 12k would be enough for it, even if it turned out not to be for the house. If the 12k is right for the house then (again when time and money permit) I could look into getting a 9k or something for the workshop building.

There is no need for an expensive refrigerant recovery system on a mini-split. You don't even need a vacuum pump to capture the refrigerant and uninstall a mini split:

1) Put a gauge set on the maintenance port of the compressor (outdoor unit) and purge the hose.
2) Shut off the high pressure release valve on the compressor unit.
3) Put the indoor unit into test mode.
4) The compressor will run and pull a vacuum in the tubing which you will see on your vacuum gauge.
5) Shut off the low pressure release valve on the compressor.
6) Pull the power at the disconnect.
7) All of the refrigerant will be captured in the compressor unit like when the system was new and the tubing will have a vacuum which you will loose when disconnecting the tubing from the compressor.
8) You can then disconnect, remove and reinstall the system elsewhere.*

This is documented on the Mitsubishi website and I have done it on my 3 head install. Works perfectly!
*You will need to pull a vacuum on the tubing and indoor head unit when reinstalling it elsewhere just like a typical (non-MrCool) mini split install.

I had a salty old HVAC tech argue with me that this would ruin the compressor on the mini-split and probably burst a line inside the compressor unit. I followed these instructions from the Mitsubishi website and it worked perfectly. I think the tech might have known whole house HVAC but was not educated on mini-splits... and had no interest in learning about them.

[Bill George]

Your shutting off the Liquid line on the unit and pumping it down into the unit condenser. Should always be done while in the AC mode. Never allow air to enter the low side, break that vacuum with a little R410a. Close off the Liquid line and Gas line service valves on the unit and Cap off all the lines and fittings to help keep out the dirt and air. Your going to need to purchase a little R410a to purge lines and add charge as needed. Even as I am still CFC approved the 30 lb cylinders locally were priced out of sight for just needing a lb or two. I found small sealed 11Lb cylinders on eBay marketed by Honeywell and sold overseas, here in US. Way cheaper than a new 30 lb one locally.

[Zachary Hoyt]

I'm learning a lot from all of your input, and I really appreciate it. I've ordered a 12k DIY Mr Cool from Zoro because they sent me a 20% coupon in the mail. Even though their starting price was higher the 20% made it cheaper than the other options. I'm wondering about a couple of other questions about the installation. I have some angle iron and a welder, so I am thinking of making my own wall bracket. I don't know how robust the bracket steel needs to be, or if what I have will be strong enough. I can also order one, but they look a bit under-engineered for what they cost.

Another question in my mind has to do with placement of the outdoor unit. The room to be cooled is abut twice as long as it is wide, with the short walls on the north and south. I had been thinking of having the inside unit about 2/3 of the way north on the west wall, with the outside unit on the north side. I could also put the inside unit on the north wall, but with 25' of line I should have enough to go around the corner, and it seems like not having it all the way at one end would help with distribution. It seems from the manual that the north wall is best for the outside part, to keep direct sunlight off it. I will be building a porch on the north side of the house next year, basically a deck with a roof over it and maybe a railing. I have not been able to find anything that says it is or isn't okay to have the compressor on a porch like this. In the meantime I'd just have to put a temporary roof/cover over the outside part to keep the worst of the rain and snow off it, if I understand correctly.

[Michael Schuch]

Your shutting off the Liquid line on the unit and pumping it down into the unit condenser. Should always be done while in the AC mode. Never allow air to enter the low side, break that vacuum with a little R410a. Close off the Liquid line and Gas line service valves on the unit and Cap off all the lines and fittings to help keep out the dirt and air. Your going to need to purchase a little R410a to purge lines and add charge as needed. Even as I am still CFC approved the 30 lb cylinders locally were priced out of sight for just needing a lb or two. I found small sealed 11Lb cylinders on eBay marketed by Honeywell and sold overseas, here in US. Way cheaper than a new 30 lb one locally.

The test mode always runs runs the unit in AC mode.

[Michael Schuch]

I'm learning a lot from all of your input, and I really appreciate it. I've ordered a 12k DIY Mr Cool from Zoro because they sent me a 20% coupon in the mail. Even though their starting price was higher the 20% made it cheaper than the other options. I'm wondering about a couple of other questions about the installation. I have some angle iron and a welder, so I am thinking of making my own wall bracket. I don't know how robust the bracket steel needs to be, or if what I have will be strong enough. I can also order one, but they look a bit under-engineered for what they cost.

Another question in my mind has to do with placement of the outdoor unit. The room to be cooled is abut twice as long as it is wide, with the short walls on the north and south. I had been thinking of having the inside unit about 2/3 of the way north on the west wall, with the outside unit on the north side. I could also put the inside unit on the north wall, but with 25' of line I should have enough to go around the corner, and it seems like not having it all the way at one end would help with distribution. It seems from the manual that the north wall is best for the outside part, to keep direct sunlight off it. I will be building a porch on the north side of the house next year, basically a deck with a roof over it and maybe a railing. I have not been able to find anything that says it is or isn't okay to have the compressor on a porch like this. In the meantime I'd just have to put a temporary roof/cover over the outside part to keep the worst of the rain and snow off it, if I understand correctly.

I went with the cheapest "known" online vendor I could find when ordering. I think the online mini-split dealers pretty near give the AC units away at very little profit and then stick it to you for all the installation supplies. The place I ordered my "non-MrCool" Mitsubishi unit from were charging double what supply houses were for the line sets, wire, mounts, etc. I have always had great luck with ordering stuff through Zoro. It usually arrives quicker than they promise. I think I ordered my last line set from Zoro because it was much cheaper than the other online AC vendors.

I made my own ground mount base for my last install out of 2" x 2" x 1/8" angle iron. It was WAY over built and 4 or 5 times the weight of a store bought base. If you look at how flimsy the store bought wall mount brackets are I think you would be VERY hard pressed to make one equally flimsy.

I chose ground mount because I have a concrete slab under our second story back deck. So the deck keeps the sun and snow off of the compressor. I also went ground mount because it is next to my daughters bedroom and I didn't want to wall mount it to where she could hear it. The outdoor compressor is so quiet that I doubt she would ever hear it if it were wall mounted. Most of the noise of a whole house AC comes from the unit starting up and coming up to speed. A mini-split does not have the initial spin up because it turns on slowly and only goes fast enough for the load where a central AC compressor usually has 2 speeds, full speed and off. The central AC compressor is about 15' away also under the same deck. I think (not being an HVAC person) that under a 2nd story deck is a perfect location as long as it is open with the ability of plenty of air flow. My ground mount compressor is about 6' in from the side of the deck so the hot air pretty much gets pushed out from under the deck instead of building up hot air under there. My compressor is held about 20" off the ground by my base to keep it above the dirt and debris.

North makes sense to minimize sun exposure heating the compressor while trying trying to cool. The top of my indoor head unit is t about 8' on a 9' internal wall and it is working very well.

My longest line run, to my 3rd bedroom, from the compressor that serves 3 bedrooms is about 35', around a corner and it has caused no issues. The only advice I would give for going around a corner is to use 4" line set covers instead of 3" so you can have a more gradual bend around the corner. I could find no line covers with an exterior corner piece available so I had to make my own out of a straight run piece by cutting it at 45 degree angles.

[Bryan Lee]

Me and a buddy installed my mini split, which came pre charged. We still needed a pump and a cylinder of nitrogen for pressure testing. Easy to get the nitro at a welding supply store for very minimal money.

[Bill George]

The test mode always runs runs the unit in AC mode.

Not all units are the same, mine had test modes in both heat and cool. Plus it has both the liquid line and gas line service ports outside the unit.

Having serviced heat pumps back in the early years (late 1970's) I watched for some of the stupid mistakes untrained installers did like not keeping it off the ground resulting in huge Ice dams around the unit, or installing under a deck. Since I worked commercial, nothing is more fun than working on a Carrier rooftop heat pump when its -5 F outside. As you might recall we were running out of natural gas and every manufacturer was building a heat pump and a lot were cr@p.

[Jim Becker]

Another question in my mind has to do with placement of the outdoor unit. The room to be cooled is abut twice as long as it is wide, with the short walls on the north and south. I had been thinking of having the inside unit about 2/3 of the way north on the west wall, with the outside unit on the north side. I could also put the inside unit on the north wall, but with 25' of line I should have enough to go around the corner, and it seems like not having it all the way at one end would help with distribution. It seems from the manual that the north wall is best for the outside part, to keep direct sunlight off it. I will be building a porch on the north side of the house next year, basically a deck with a roof over it and maybe a railing. I have not been able to find anything that says it is or isn't okay to have the compressor on a porch like this. In the meantime I'd just have to put a temporary roof/cover over the outside part to keep the worst of the rain and snow off it, if I understand correctly.

I suggest you wait for your final decision until you have your unit so you can visually judge the best position for the inside unit and lineset length/outside position with that additional input. There is not likely an overall ideal for both in many cases, so "eyes" on will help you zero in the best possible positioning for both. Your room usage matters in that because you may not want the indoor unit blowing directly on a "high use" place. It's not unlike a similar situation with a traditional duct...some positions are not comfortable for the humans for hot/cold direct air flow.

[Bill Dufour]

My first install of a outdoor unit has a minor issue. There is a simple slide off cover on one end where the lines and power connect. I should have prebent the lines into a sharper bend before final install. The cover jumps loose in a day or too. It hangs loose until I bother to clip it back. There is not enough slack to rebend the tubes. I should have tested the cover fit before charging the system. I made sure to bend and check several times on the next one I installed. I think it also has a screw to keep it in place as well as the clips.
Bill D

[Tom M King]

Tight bends are easy with a proper tubing bender, but really shouldn't be attempted without. This crimped line (sorry couldn't find the picture of the crimp) was installed by a "pro", and the reason I had to replace this line set. You can see the crimp in the short piece of old 3/4" line in the back of my truck behind the bender box if you blow the picture up. I cut that piece out to keep it as a souvenir.

The brazed joint was leaking. It wasn't done anything like properly. There was another leak behind the brick in the wall, so no choice but to redo the whole line set. This in a lake rental house. This is why I do everything myself.

These tubing benders do a pretty, tight bend, and I couldn't have done without them on this one job.

Line cover and line set from Supplyhouse.

[Bill George]

We used Imperial brand lever benders, they did a beautiful job. The guys that installed a lot of commercial jobs would anneal the hard refrigeration grade copper and bend, the soft ACR copper of course did not need too. https://www.amazon.com/Imperial-Tool-364FHA06-Lever-Bender/dp/B001HWA97Y/ref=asc_df_B001HW88ZE?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80882941400099&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584482468520025&th=1

[Tom M King]

Those look good, but you need a separate one for each different size. The kit I bought works with all common sizes, and comes with the adapters to do "reverse" bends. It works plenty good enough. Like everything else, it's gone up significantly in price since I bought mine a couple of years ago, but the whole kit is still less than a 3/4" Imperial bender.

3/4 is the largest I've bent with it, but it did that with very little effort, and made pretty bends.

https://www.trutechtools.com/BlackMax-BTB300-Tubing-Tools-Premium-Ratcheting-Tube-Bender-w-Reverse-Bend-1-4-in-5-16-in-3-8-in-1-2-in-5-8-in-3-4-in-7-8-in-OD-Tubing

If I did it all the time, I'm sure the Imperials would come in good, especially when you need more than a 90 degree bend, and would be worth the extra cost.

edited to add: I needed the reverse setup mode to bend the old vapor line stub near the house in a fairly tight spot on that job. It worked fine. I'm not sure the Imperial handle could have been swung in that spot, but it could have been bent up to go another way.

[Michael Schuch]

In a previous post I believe I said that I order my supplies from Zoro at a great savings. I was wrong. I order my supplies / material through www.supplyhouse.com (http://www.supplyhouse.com) and have had excellent dealings with them. Their prices are a lot lower on things like line sets, fittings, plumbing parts, etc. And their shipping has always been VERY fast! (Faster than Amazon)

[Jim Becker]

Michael, I ordered the pad for my condenser from Supply House today...price was the same as Amazon and they could have it here Thursday instead of next week for under five bucks. I'd use them again for sure.

This puppy also arrived from Costco today...

489496

[Bill Dufour]

Costco ells mini splits? I knew they sold coffins and urns, special order only, not off the shelf.
Bill D

[Jim Becker]

Costco ells mini splits? I knew they sold coffins and urns, special order only, not off the shelf.
Bill D
They partnered with Mr Cool and sell systems at costco.com. These are not "in store" items. A "yuge" amount of products that Costco sells are not physically in the stores because of their nature.

[Brian Elfert]

They partnered with Mr Cool and sell systems at costco.com. These are not "in store" items. A "yuge" amount of products that Costco sells are not physically in the stores because of their nature.

I just wish Costco.com would show what is in the store and the current price like most big retailers these days. They do it a little bit now for some stuff, but they show the delivered price, not the in store price which is usually less.

[George Yetka]

You dont need to do it all. Just do the following.

-Run lineset. If its an easy path
-Flare connect the 2 ends of the lineset to the 2 pieces of equipment. Should only need a flaring tool for this but I recommend a flare sealant called Nylog it will make a better seal
-Condensate is easy
-Electric is easy.
-low voltage to stat or a wireless remote is easy

Hire someone to evacuate and charge This will cost a lot less than buying the tools.(DONT LET THEM SELL YOU REFRIGERANT) it is in the condenser already in 99% of residential single zone units.

[George Yetka]

Commercially I have installed 40 splits/ vrfs and on each of them we have a service guy follow behind for evac and charge. That is the most complicated part and requires the most amount of specialty tools.

[Bill George]

Commercially I have installed 40 splits/ vrfs and on each of them we have a service guy follow behind for evac and charge. That is the most complicated part and requires the most amount of specialty tools.

What brand did you use?

[Bill George]

FYI Cleaning those mini splits. A year or more ago my mini just was not cooling right. After some investigation in spite of regular cleaning of the thin washable filter I found the blower wheel Packed, yes full of dirt. Sure you could try to remove and clean but my unit was right next to the wall on the right side. I was able to open the tab vents when the unit was off and then get a long narrow brush in and get a lot of dirt off. I then took my air compressor hose and long nozzle made from 1/4 copper and blew the wheel and coil clear. It was like a miracle, wow now I have air flow and it heats and cools like it should.

Since then I did some research and found they make cleaning boots or covers for the units (Amazon) so when you clean with air or water it contains the mess. I also purchased an air powered soapy water sprayer with a long nozzle.
Yes I had a big room cleaning job when I got done, in spite of covering with what I had to work with.

[Jim Becker]

Yes, mini splits need periodic cleaning...just like "conventional" systems that also get gunked up.

[Bill George]

Yes, mini splits need periodic cleaning...just like "conventional" systems that also get gunked up.

It had only been in 16 months.... no way to put in a better filter but I did spray with filter coating.

[Tom M King]

When I saw what was needed to clean the one we had in for my Mother's suite, I recovered the refrigerant, disconnected the indoor unit, and took it outside to clean. I keep one recovery tank that I know has clean 410a in it, so don't mind putting it back in a system.

I'm buying the install hanger kit before I do that again though. The hard part is balancing the indoor unit on something while you hook the lines back up. I posted this earlier, but haven't bought it yet.

I just need to figure out when is the best time for the cleaning, and do it on some schedule.

https://www.supplyhouse.com/Rectorseal-97705-Mighty-Bracket-Mini-Split-Installation-Support-Tool?utm_source=google_ad&utm_medium=search_dsa&utm_campaign=Dynamic_Search_Ads&gclid=Cj0KCQiAgribBhDkARIsAASA5buaX4qHI0BZDLG75wkd xGNCx7AjfDjY-OCtvCQtjwMNbyhIbFacXvoaAlilEALw_wcB

[Bill George]

This is what I am going to get for next time cleaning and I did buy a air powered long nozzle soapy water cleaner. On mine the flaps are on little stepper motors so when its off, no power you can open them up by hand and clean the blower wheel. This cleaning is big draw back for the minis.

Link here> https://www.amazon.com/Conditioning-Cleaning-Waterproof-Support-Protector/dp/B083S85X97/ref=sr_1_5?crid=2LM0M12DO13QX&keywords=mini+split+cleaning&qid=1668257179&sprefix=mini%2520split%2520cleaning%2Caps%2C101&sr=8-5


And the sprayer> https://www.amazon.com/dp/B01E0FXD18?psc=1&ref=ppx_pop_dt_b_product_details

[Tom M King]

That looks good with the drain. I'll try that next time too. I had let it get way too bad before I cleaned it last time. It had black mold growing in it. It was way too bad to want to clean it in the house.

[Zachary Hoyt]

The outdoor unit came today, so now I may be ready to start work. I am still confused about the electrical requirements, even after getting the manual and reading that part of it. It gives the MCA as 19 amps and MOP as 25 amps. Does this mean I need a 25 amp 120 volt breaker, or can I use a 20 amp breaker? Does the breaker need to be a GFCI?

I am planning to install the breaker in the meter main, as there are 8 slots available and it is only 10-15 feet from where the outdoor unit will be mounted. This brings me to another question I have been puzzled about. Do I need a power disconnect next to the outdoor unit, or since it will be connected to the meter main which is in a direct line of sight and 10-15 feet away, is that sufficient?

A third question which has been bothering me is the type of wire and protection to use from the meter main to the outdoor unit. The wire between the indoor and outdoor units is MC of some kind. I don't know if I need to use conduit and single THWN conductors, or if I can use MC wire too, or what. The electrical inspector I was using and who was going to put in a mini split for us is now filing the paperwork for our final inspection, but I guess I will need to get him or find another inspector to approve the wiring after I put it in. So far I haven't told him I have bought a mini split and am planning to put it in myself. I don't know if he would give me a harder time on this job. It seems kind of silly to pay another $160 or whatever to get this single breaker and wiring run inspected, but I guess that's what I will need to do, to be legal.

One more thing is what size of angle iron I need to support the outside unit. I have lots of 1/8"x2" or so angle iron from bed frames. I have a little bit of 1/4" x 3 to 4" angle iron too, enough for the job but not much extra. It seems like these are definitely overkill, but the light ones may be too light. I can also weld the angles into boxes if using the lighter ones, if that would help. I have a stick welder so the welds are not pretty but can be quite strong. I can also add some diagonal bracing underneath if that would help. It says in the book the back has to be 6" from the wall, so the whole thing would stick out 18" or so from the wall, I guess.

I'll be grateful for any advice on these various matters. It all feels a bit overwhelming now, but I'm sure it can all be dealt with in the end.

[Jack Frederick]

In cleaning mine I do not use the commercial boot that is offered. I took some 5 or 6 mil plastic sheet from the roll I had when we put it down for the slab and taped it to the walls. I took one of my large plastic garbage cans and gathered the plastic into the can. Remove the cover completely. It is essential to a good job to be able to access the entire coil. Frequently folks will simply clean the face of the coil but a good 40% of the coil drops down the back of the unit. Get to close tot he ceiling and you can be two blocked. I use a Calgon coil cleaner in. Sprayer, but make sure it is approved for your MS. Then rinse into the drain pan. As noted above the small diameter curved blades fan is a bear to clean and you have to be careful not to damage it. I am Reluctant to remove the fan assembly but a better mechanic may do that. I use the sprayer to wash the fan in position. Either a flux brush or long Q-tips or whatever you can get your hands on that will completely access and clean the entire wheel. I’ve actually made a small kit using a 1/4” irrigation tube. From the garden hose attach the 25# pressure red valve to a 1/4” valve to a another piece of tubing. I think I’ll tape it to a piece of brazing rod so it is small enough to get into the tight tight qtys. I have not actually done this with the tubing but I think it will work out well and I have all the parts I use in the garden. Oh, cover the floor out a few ft to catch any overspray. I love my minisplits but they are a pitn to clean.

[Tom M King]

Zachary, the angle iron you have is more than strong enough. You don't need to use up the 1/4" thick stuff.

[Zachary Hoyt]

Thanks, that's very helpful. I tend to overbuild, or worry, so knowing the lighter stuff is OK will make things a lot easier.

[Brian Gouldman]

Not a code expert but my understanding and how I installed my own was that you need a disconnect “within sight”. I guess the question is if a breaker is considered a “disconnect” and if you can truly determine the circuit is de-energized from the outdoor unit. I believe you also need a gfci outlet nearby for hvac servicing. I found a Siemens disconnect that has a built in gfci outlet and use that to serve both needs in my own installation.

For your wiring, it sounds like a you are describing a full outdoor run from feed to the unit? Assuming you are making a new dedicated run I can’t imagine you can’t use MC also as long as it is suitable for outdoor applications and terminated at both ends with the proper fittings. Hopefully now that I’ve replied the more knowledgeable members we’ll come in to correct or confirm what I’ve said :)

[Zachary Hoyt]

Thank you, that helps narrow down the questions a good bit. I do have a GFCI outlet in the same area of wall where the mini split will go. It'll be no more than 4 feet from it, and maybe less. It's likely to be one of the factors in just where the mini split does go. If MC can be used that will be a lot easier than conduit. I'll have to try to find out if a breaker is considered a disconnect.

[Bill George]

You need a disconnect within sight and lockable. I have a pull out disconnect right next to mine. My inside unit gets its power from the outside unit and they sell a special Romex like cable with the correct size wire and color code that makes for a foolproof connection. I used Sealtite or Liquid tight conduit for both the power connection to the outside unit and from the inside unit to the outside unit. All must be grounded, My unit is a 16,000 BTU and called for a 20 amp 230 volt circuit, yours might be different. I am a retired licensed electrician and HVAC/R person, but you need to follow local Codes.

Yes it needs to have a dedicated circuit of its own.

My unit sets on a 4 inch high slab and then treated 4x4s and its never had an ice build up issue.

[Jim Becker]

The outdoor unit came today, so now I may be ready to start work. I am still confused about the electrical requirements, even after getting the manual and reading that part of it. It gives the MCA as 19 amps and MOP as 25 amps. Does this mean I need a 25 amp 120 volt breaker, or can I use a 20 amp breaker? Does the breaker need to be a GFCI?

The chart in the manual is a bit confusing so I clarified things with MC technical support. Steven, the CSR I worked with, was pretty good. Interpolating from that conversation because my unit is much larger, you should be fine with a 20 amp dedicated circuit. This is hard-wired so I suspect that a GFCI isn't required. Depending on the distance, you can use 12-2 copper or 10-2 copper. But you do need a physical disconnect and I like to install a surge unit there. I used an Intermatic AG3000 for that and it's compatible with both 120v and 240v units. The disconnect goes on the wall near the condenser/compressor. A weather tight flexible whip is used between the disconnect and the unit. The bottom line here...you need to buy some specific parts to complete your installation.

The Gen 4 units have the control/power cable from the indoor unit to the outdoor unit pre-connected to the indoor unit and yes, it's a coated MC cable. It gets bundled with the line set from the indoor unit to the outdoor unit. The dedicated circuit for the system only connects to the outdoor unit. The pathway for the power source is unlikely to be the same path as the control/power cable that passes between the indoor and outdoor units and should use the same kind of wire you are already wiring your home with inside the home. That's "Romex" for me.

If you are planning on wall mounting the outdoor unit, don't be afraid to do yourself a favor and buy a designed for purpose wall hanging bracket. If you do decide to fabricate it, at least look carefully at the design of the brackets that are sold so you understand the support aspects. Even with the small system you are using, the outside unit is darn heavy and you'll also want it mounted with proper vibration dampening.

[Zachary Hoyt]

Thank you Jim, I hadn't thought about surge protection but it makes sense. The weather tight whip does seem nice, and I can use another slightly longer one to get to the meter main from the disconnect. All the wiring for this will be outside, coming out from the bottom part of the meter main and then along the top of the foundation and back up to the disconnect. I used NM cable inside, except for some UF 6-3 to the stove since I had to buy that anyway for the underground run to the shop.

That's great about being able to use a 20 amp breaker. I have a leftover 20 amp AFCI breaker that I can use instead of having to buy a 25 amp.

I'll have to think more about buying a bracket. They seem kind of mickey mouse from the pictures I've seen, what with having to be adjustable and all, so I thought that by making my own I might be able to make it better, but that may not be the case for all I know.

[Bill George]

Unless your mounting for a second story house or need to get out of the way of a mower why mount on the house? Mine sets on a 4 inch concrete slab and 4x4s and for here that keeps it out of the snow and ice build up. Do use stranded wire for the hook up on the connecting wire between the inside and outside units. MC cable is not approved for wet locations, use only the liquid tight or regular conduit.

Your nameplate is suppose to state the Minimum circuit size if its UL approved that is, some Chinese is not marked as such.

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[Zachary Hoyt]

The MC cable is factory installed to the indoor unit and to be connected to the outdoor unit, and I am not going to mess with it. I assume the mini split is UL listed since Mr Cool is a large company. I am going to build a porch with a roof on this wall of the house next summer, so I can't put it on the ground as there would not be enough room under the porch floor. Also it's too cold here to pour concrete now.

[Bill George]

The MC cable is factory installed to the indoor unit and to be connected to the outdoor unit, and I am not going to mess with it. I assume the mini split is UL listed since Mr Cool is a large company. I am going to build a porch with a roof on this wall of the house next summer, so I can't put it on the ground as there would not be enough room under the porch floor. Also it's too cold here to pour concrete now.

MC cable and the fittings must be approved for outdoor wet locations, not all of it is.

[Zachary Hoyt]

It's got some kind of rubbery coating, and the whole thing is indeed UL approved.

[Bill George]

It's got some kind of rubbery coating, and the whole thing is indeed UL approved.

Looks like your good to go, the old MC stuff and perhaps where you were buying from in the past did not know the difference, but you got the outdoor rated.

[Jim Becker]

The MC cable on the Gen 4 units is coated specifically because of the conditions it will be used in. This is not MC cable from the big box store...it's custom stuff.

Zachary, do you have the type of outdoor meter box that also has the main disconnect and space for a few circuits including a feed to an inside breaker panel (sub)? If so, what you propose to do makes sense, but if you have a standard meter box that feeds a main panel inside of the house, it does not make sense to me.

[Zachary Hoyt]

Thanks for the clarification on the cable, Jim. Yes, around here the thing you described is called a meter main, but that may be a regional term. They are required for mobile homes, and sometimes used in houses too. When I put the new service in back in April I went with that because it provides an outside disconnect so that firefighters can shut off the power from outside if necessary, and it saved having to run the main wire around the corner and down the outside wall of the house in conduit. I wanted to have the panel where it had been before, but without all the conduit which would have been in the way of building the addition, and also looked messy.

There is a 200 amp breaker below the meter, and below that are 8 spaces for breakers. The 200 amp breaker feeds both these 8 and the big panel inside the house, which is really a subpanel. The ground is connected to the neutral at the meter main, and the ground rods are right there too. So far I haven't used any of the 8 slots, but this seemed like the perfect job for one of them, since it will reduce the wire run by half and keep it all outside.

[Jack Frederick]

I like the wall brackets. Those shown in the photo are on my house and have been for 12 & 9 yrs show no deterioration and are solid. Don’t put them outside the living room or M Br as you may pick up some resonance. I did say “may” but why risk it. Sitting as you do between the Great Lakes and the Atlantic with the attendant storms and accumulation I would definitely raise it at least above your snow loads. They are no fun to dig out. It does keep them cleaner also. Elevation also keeps critters out of the unit. I got a call to look at a unit in MA once. When I walked around the corner of the house I thought I had vertigo. It was actually hundreds of garter snakes that made the grass seem to be moving. As I was called out to look at the condensing unit I worked my way over and the unit was frilled with snakes and they had gotten up into the electronics. I’ve seen several of those over the years and a snake will get hit with 220, roll from board to board and die taking the unit with it. The owner wanted a new unit. I told him to call his insurance company.

[Jim Becker]

I agree that it sounds like a very logical way to take advantage of the meter/main panel location, but you'll want to check to see if you are permitted to use a flexible conduit "whip" between the disconnect and the meter/breaker box in this situation or if you have to use regular PVC conduit. I'd personally choose the latter for "on the building". The flexible stuff between the disconnect and the system is a different situation.

[Zachary Hoyt]

I left a message for the inspector this afternoon, and I hope to find out soon. I could certainly do the conduit thing, if that would be better. I thought that a waterproof flexible conduit might be better than a PVC one that would probably leak somewhere, but I suppose the PVC would be more protective from physical damage.

[Jim Becker]

If the PCV is properly glued, it's not going to leak in this application.

BTW, here's what the surge do-jobbie looks like installed on the disconnect. It hooks into the "line" side.

489877

[Zachary Hoyt]

Thanks for the picture, that's very helpful. I had looked up the part number you gave earlier, and when I looked at the picture I was baffled as to how it would interact with the disconnect. I've glued PVC when I installed it before, but have been told that the expectation is that outdoor conduit will always fill up with water from somewhere.

[Zachary Hoyt]

I like the wall brackets. Those shown in the photo are on my house and have been for 12 & 9 yrs show no deterioration and are solid. Don’t put them outside the living room or M Br as you may pick up some resonance. I did say “may” but why risk it. Sitting as you do between the Great Lakes and the Atlantic with the attendant storms and accumulation I would definitely raise it at least above your snow loads. They are no fun to dig out. It does keep them cleaner also. Elevation also keeps critters out of the unit. I got a call to look at a unit in MA once. When I walked around the corner of the house I thought I had vertigo. It was actually hundreds of garter snakes that made the grass seem to be moving. As I was called out to look at the condensing unit I worked my way over and the unit was frilled with snakes and they had gotten up into the electronics. I’ve seen several of those over the years and a snake will get hit with 220, roll from board to board and die taking the unit with it. The owner wanted a new unit. I told him to call his insurance company.

Thanks for the advice. That's pretty interesting about the snakes. Are they attracted to the heat? The living room is the only choice I really have to keep the condenser on the north end of the house, which seems like the logical thing. I had had the impression that the mini splits were supposed to be pretty quiet, but I guess vibration is different from noise, though not unrelated.

[Jack Frederick]

it was like a Teddy Bear Picnic but with snakes. It was late spring early summer as I recall. From a heating perspective any sunshine you can get on the unit is bonus so S side is best, but they have to fit the house. MS’s are quiet.

[Jim Becker]

I've glued PVC when I installed it before, but have been told that the expectation is that outdoor conduit will always fill up with water from somewhere.

That's super true for underground conduit for sure which is why using cable/conductors that are rated appropriately is important. It should be substantially less of an issue for what you need to do to connect your disconnect to the meter/breaker cabinet if it's done properly. I'd likely still use THHN, which is what's also typical in the pre-configured flexible whips.

[Zachary Hoyt]

it was like a Teddy Bear Picnic but with snakes. It was late spring early summer as I recall. From a heating perspective any sunshine you can get on the unit is bonus so S side is best, but they have to fit the house. MS’s are quiet.

That's a whole new line of thought. I read somewhere in the manual, I think it was, that the condensor should be kept out of direct sunlight, but maybe I dreamed that. I'll have to go back and look it up again.

[Zachary Hoyt]

That's super true for underground conduit for sure which is why using cable/conductors that are rated appropriately is important. It should be substantially less of an issue for what you need to do to connect your disconnect to the meter/breaker cabinet if it's done properly. I'd likely still use THHN, which is what's also typical in the pre-configured flexible whips.

That makes sense about underground vs above ground. I'd have thought THWN was required in an outdoor conduit, but maybe I'm mixed up.

[Jim Becker]

That makes sense about underground vs above ground. I'd have thought THWN was required in an outdoor conduit, but maybe I'm mixed up.

THHN or UF is generally indicated for these outdoor conduit situations. The former is easier and less expensive for the short run you need to make between the disconnect and the power source. UF is "less fun" to terminate, too, because of the nature of the cover that fully engulfs the conductors. It takes a little time and careful knife skills to strip it back...I just used a 50' length of it to get between the new shop building and our shed and I did not enjoy that part of the work!! THHN is "just wire" and easy to work with. The only reason I went with UF for the above mentioned run is because I was doing direct burial.

[Bill George]

THWN or TW or THW wire is the only markings that say its for wet locations. Some wire may be marked THHN/THWN as dual purpose.

[Jim Becker]

My apologies for the incorrect notation. Bill is correct.

[Zachary Hoyt]

I just got off the phone with the inspector and now I know what is required by him. He says 12 gauge in conduit or 12-2 UF to the disconnect, and then I am fine to use one of those whips to the outdoor unit. He also approved the idea of a surge protector on the disconnect box. It'll take a little time for everything to arrive, but I was going to wait anyway since it's going to be highs around freezing for the next week anyway. I'm sure it will warm back up eventually for a day or two.

[Jim Becker]

I actually bought my whip and surge suppressor from Amazon and had them in a day and two days respectively. Neither of the two 'borg locally had either of those items. I had to buy the UF for the run to the shed from the local electrical supply house. They were certainly an option for the whip and surge protector, but they tend to be pricey as they are the only dedicated game in town...while being competitive with wire for some reason.

[Zachary Hoyt]

I was going to buy the disconnect box from Amazon but they said it was not deliverable in my area, so I ordered everything on eBay. For $153 with tax I got an AG-3000 like you described using, a pullout disconnect, a 20 amp QO breaker that is not AFCI, 25 feet of 12-2 UF-B wire, and a 6 foot 10-2 liquidtight whip. Maybe I would have done better at a store, but it's a long way to get to one from here.

[Zachary Hoyt]

I've been thinking more about where to install the mini split, now that it is here. It seems there are 3 options that are all plausible, but I don't know which factors are more important. One would put the indoor unit about 10 feet down the west wall of the living room. This is right above the seating area, which I have heard is not ideal. It's about 1/3 of the way down the 30 foot overall length of the downstairs. The second would put the indoor unit in the middle of the north 15' wall, which seems less than ideal because it's at one end of the long room, and also right above the chairs. The third option would put the indoor unit about 15 feet down the east wall. This is away from the seating area, near the foot of the stairs where there is a walkway. The downside to this spot is that it is only about 3 feet from the stairwell, so the heat might just go upstairs instead of warming up the downstairs in the intended way.

I'm wondering if proximity to where people sit is more or less of a thing to avoid than proximity to the stairwell. I don't understand how effectively the air handler moves the heat or cooling around the space. The electrical bits won't get here for a while, so there's plenty of time to figure this all out. All of the options would leave the outdoor unit on the north wall of the house. Two would allow it to go on the future porch, and two would allow it to go next to the future porch, by the existing new room. I could put it on an old concrete slab which I could move to this location, or on a wall bracket. On the porch it would be able to be under the porch roof, but it would be in the way of putting a swing on the porch, if we wanted to do that. Off the porch it would require its own little roof to be added. There seem to be a lot of variables. I'll be grateful for any advice.

[Jerome Stanek]

I agree that it sounds like a very logical way to take advantage of the meter/main panel location, but you'll want to check to see if you are permitted to use a flexible conduit "whip" between the disconnect and the meter/breaker box in this situation or if you have to use regular PVC conduit. I'd personally choose the latter for "on the building". The flexible stuff between the disconnect and the system is a different situation.

Here we use water tite flexable greenfield

[Bill George]

I've been thinking more about where to install the mini split, now that it is here. It seems there are 3 options that are all plausible, but I don't know which factors are more important. One would put the indoor unit about 10 feet down the west wall of the living room. This is right above the seating area, which I have heard is not ideal. It's about 1/3 of the way down the 30 foot overall length of the downstairs. The second would put the indoor unit in the middle of the north 15' wall, which seems less than ideal because it's at one end of the long room, and also right above the chairs. The third option would put the indoor unit about 15 feet down the east wall. This is away from the seating area, near the foot of the stairs where there is a walkway. The downside to this spot is that it is only about 3 feet from the stairwell, so the heat might just go upstairs instead of warming up the downstairs in the intended way.

I'm wondering if proximity to where people sit is more or less of a thing to avoid than proximity to the stairwell. I don't understand how effectively the air handler moves the heat or cooling around the space. The electrical bits won't get here for a while, so there's plenty of time to figure this all out. All of the options would leave the outdoor unit on the north wall of the house. Two would allow it to go on the future porch, and two would allow it to go next to the future porch, by the existing new room. I could put it on an old concrete slab which I could move to this location, or on a wall bracket. On the porch it would be able to be under the porch roof, but it would be in the way of putting a swing on the porch, if we wanted to do that. Off the porch it would require its own little roof to be added. There seem to be a lot of variables. I'll be grateful for any advice.

Keep in mind that the unit only has so much air flow and place In the room needing the most heating or cooling. The outside unit, remember warm air rises and can be trapped and then recirculated by an overhang or porch floor over. It does not need a roof and since your on the North side sun should not be a problem. You need to leave room for service and cleaning. Mine is very quiet both inside and outside units.

[Zachary Hoyt]

Thanks, that makes sense. I think it's supposed to be the right size to heat or cool the whole downstairs area, but I don't know how if it will do it evenly.

The book that came with mine says the outdoor unit should be "protected from prolonged periods of exposure to direct sunlight or rain" and it does rain here, sometimes for prolonged periods like days at a time. That is why I had thought I needed a roof of some kind over it to keep the majority of the rain off. I hadn't thought about the rising hot air being trapped, but it makes sense.

[Bill George]

Mine sets on the West side of the house, under a 24 inch overhang. Which is 5 feet or more above it. The fan draws air from the back side and exhaust out the front blowing it a good 4- 8 feet away. Its in the sun part of the day, but the overhang helps some and any outside unit had better be able to take rain and snowfall. I have the shortest line set I could buy 15 feet and I just needed to remake one factory flare.

My room size is 15x20 and the air on high will just make the 20 ft. The dampers on mine I can preset and the unit remembers those settings for Heat and for Cool each. This is a 15,000 BTU which is ok but when it gets below -5F it struggles to keep up.

FYI commercial units on the roof are 100% in the sun and rain.

[Zachary Hoyt]

Thanks, this is useful to know. I am a bit baffled by the manual. It seems that putting the outdoor unit on the wall next to the porch may be the best thing. The roof there overhangs about 25" but it's about 12 feet up. I guess, as with many things, it's a matter of picking what seems like the most reasonable option out of the less than ideal choices and then hoping for the best.

[Jim Becker]

The thing is, a "yuge" percentage of the outdoor HVAC units, traditional or mini splits are not covered over, in my observation. I truly wonder if it's really an issue. My overhang on the shop is 12" and the unit, mounted on the ground, must be 12" from the wall. I'm honestly not worried about it.

490051

[Ken Fitzgerald]

The thing is, a "yuge" percentage of the outdoor HVAC units, traditional or mini splits are not covered over, in my observation. I truly wonder if it's really an issue. My overhang on the shop is 12" and the unit, mounted on the ground, must be 12" from the wall. I'm honestly not worried about it.

490051

My AC condenser isn't covered. I do put a cover on it in the late fall as my neighbor's large maple massively overhangs my house and shop. I don't want to have to clean the leaves out of the condenser. With a high efficiency furnace, the condenser isn't used in the winter. It would be interesting to know which direction the fan circulates the air. If the air is coming up through the condenser, I'd be less worried about it.

[Jim Becker]

My AC condenser isn't covered. I do put a cover on it in the late fall as my neighbor's large maple massively overhangs my house and shop. I don't want to have to clean the leaves out of the condenser. With a high efficiency furnace, the condenser isn't used in the winter. It would be interesting to know which direction the fan circulates the air. If the air is coming up through the condenser, I'd be less worried about it.

With a heat pump, the condenser/compressor is used year-round. The fan blows out away from the wall on these mini-split units, while the fan on the heat pump on our house blows up or down...I never checked. So the fan direction isn't a factor with the mini split and weather. I somehow think that the weather guidance is more about optimizing things since it's generally impractical to have something like a roof over these things and most of them don't. Just take a look at any multi-family apartment tower around the world. The units hang out on the outside of the building and are essentially unprotected from weather, sun, etc.

[Kris Cook]

Here is my install. Bought wall-mount brackets and bolted the unit to the brackets through rubber pads.

12-2 romex to the box on wall (internal wired during construction). Stranded inside sealtight conduit from box to unit. Also put the control wires inside sealtight to inside of the lineset cover.

-0.3 degrees here this morning in Montana. T-stat in shop set at 60 degrees overnight. 60 degrees in the shop this morning. 70 degrees now with the wood stove taking over duties.

[Zachary Hoyt]

Thank you all, that's very helpful. I won't worry anymore about the rain getting on it. The pullout box arrived at the post office today, so now I just have to wait for the other 4 packages to be delivered and the weather to warm up a bit. It's going to be up to 40 next week, if the shadows of these things remain unaltered by the future.

[Zachary Hoyt]

The forecast today was for low-mid 30s and cloudy but no rain, so I went ahead and put in the mini-split. I started about 8:15 to make the brackets, and didn't get them welded up till about 9:30, as I had to get the old stick welder out of the shed and over to the workshop. Most things went pretty smoothly, but a few were odd. For instance the mounting screws for the indoor unit were supposed to be screwed into studs, but they were only 1" long. Luckily I was screwing them into plywood anyway. I had just barely enough length on the lines, and a few more inches would have been nice.

I tested it and it does work, both on hot and cold, and showed no leaks when I checked with soapy water both before and after the test run. I have not wrapped the lines because I am a bit confused by what the manual says. There are two of those sticky pad things, and I am not clear if one gets wrapped around each line at the air handler connections, or if one gets wrapped around both of them and the other one around the other two connections by the compressor. I am also not clear how long the drain hose should be. I guessed it should come down to the corner where the lines go horizontal, but maybe it should end higher up. I also don't know if I need to wrap the lines under the addition, or if they can just hang from the bottom of the joists as they are. I'll need to order a line cover kit for the part on the outside of the house, I imagine.

The indoor unit is very quiet and the outdoor one is pretty quiet on the outside of the house, but when I was running the unit at max heating for 5 minutes during the test run it made the wall vibrate, so from inside it sounded like there was a diesel engine idling on the side of the road out there. I don't know if it would be so loud under normal conditions. I'm very thankful for all the help with this project from kind folks here.

[Maurice Mcmurry]

Mr. Cool and Pioneer appear to be identical. Good Job Well done. I will zoom in on your insulation questions.

[Bill George]

Your allowed to run Romex exposed and unprotected from the main box to your disconnect? Instead of bolting to the house where vibration can and will be transmitted to, I would have set on concrete blocks. Good job with no leaks!!

[Zachary Hoyt]

Thank you both. I was lucky to get it hooked up with no leaks. The electrical inspector said I could use conduit or UF cable, which is what that is.

[Jim Becker]

The two sticky pads are for the individual connections where the line set attaches to the tails from the interior unit. They are to keep things quiet so the connections don't vibrate together. Once you have each of those those wrapped, you do the remaining wrapping to finish up and make things neat. Electrical tape is your friend for keeping the non-adhesive wrap tape clean and neat; you can buy white if you're anal like me. :) I'm surprised that the inspector is fine with that UF "uncontained" the way it is for the connection to the breaker from the disconnect. But all decisions are local... ;)

[Zachary Hoyt]

Thanks, that's very helpful. I've got a roll of white electrical tape already since I had to use a little to mark the ends of the neutral on the service installation where all three wires were black. I'll plan on wrapping all the exposed (outside the building) lines if I have enough of the non-adhesive tape to do it. About the wire, that's what he told me on the phone, but maybe he'll feel differently once he sees it.

[Dwayne Watt]

Did you install isolator pads between the wall bracket and outdoor unit? Effectively, you need isolation on both sides of either the mounting bracket or the outdoor unit housing to dampen any vibration coming from the outdoor unit (little or no metal to metal contact). Described differently, either the wall bracket or the housing foot need to be sandwiched between isolator material at the bolted connection between the two, not on the wall itself.
Also, your brackets look pretty solid (stiff). That's not helping your vibration/noise transmission conditions. Probably too late for this winter, but a ground mount would effectively eliminate all equipment related indoor noise.

[Zachary Hoyt]

Thanks, that makes sense. I did put the provided rubber pads under each foot, on top of the bracket, but the bolts of course go right through both pieces and probably carry the vibrations. Pouring a pad under it is probably indeed the best bet once it warms up in the spring.

[Bill George]

I used white duct tape, both lines are insulated and I bundled both together so it looks nice.

UF is for underground and its the same as Romex when it comes to protection, never can be exposed like you have it without protection. I am thinking your Inspector thought it was going to be buried! Re-reading your post it appears the Inspector has not seen it yet.

You can place the rubber cookies under the unit and place on concrete blocks. Your not going to like it when that angle starts rusting. Good job getting it in with no leaks and working right off.

BTW here in Iowa today it was in the 50s and will remain the 40-50 degree range all week. I don't know where your at but last week here it was darn cold. Just saying with the Quicksetting Ready Mix you can pour concrete. Leave the angle in place until the concrete pad is cured and then lower down on treated 2x4 or other if needed, and the pads.

[Dwayne Watt]

I was intrigued by the UF cable question. A quick internet search indicated that UF can be exposed per the NEC as long as it is not located such that it can be damaged. The example that was shown was UF cable stapled to wall siding under an eave to provide power to an outdoor light. The example for this mini-split installation may or may not meet that expectation for damage protection.

[Jim Becker]

That's my concern as well, Dwayne. The protection aspect.

[Zachary Hoyt]

This week the electrical inspector finally came out and looked, and approved the installation with the UF exposed. It is run along the wall, and for a short distance, so it's not entirely vulnerable, but not as protected as it could be. The inspector had COVID for a couple of weeks and was not able to work till he got some energy back, which is why it took a little while for the inspection to be done.

[Bill George]

How does it work in the cold weather? Mine is struggling today 4 degrees F outside with a 10 mph wind and its heating a 12x20 glass on 3 sides *thermal pane porch.

Nope exposed UF like that would never be approved here, same as Romex- NM outside never.

[Jim Becker]

Bill, the 3rd and 4th generation Mr Cool units are "good" down to -13ºF.

[Tom M King]

The 18k unit we put in for my Mother's suite cooled about 7,000 sq. ft. through the hot season, so I decided to try it for heating. It's only gotten down into the high 20's a couple of nights, but we haven't needed to turn on any other heat.

I am using a couple of fans to keep it circulating through the rest of the house. The way our house is laid out, with the dog complex across the back, it goes in a big circle. She likes 74 in cold weather, but the rest of the house hasn't gone below 71, which is fine with us and the dogs.

I remain impressed with the mini-split. It's what I consider an offbrand - Chinese made Tosot, but after getting over it losing a charge put in by a pro, it's done perfectly. I had to get one on very short notice-same day-and was the only one in stock a our local HVAC supplier.

[Jim Becker]

Today's inverter designs are surprisingly efficient, even at the margins of their operating conditions. So I'm not surprised at what you said, Tom.

[Zachary Hoyt]

I haven't run mine below the mid 20s, and mostly only when the outside is in the mid 30s or higher. The wood stove heats the house nicely on colder days, and those are mostly what we've been having since I put it in.

[Bill George]

My glassed in porch (12x20) the thermal pane has a R value of perhaps 3 and If I pull the drapes at night the Mini does an ok job down to -10 or so. But when the wind is blowing and no solar gain its a tough one. Daytime not a problem but its a poor application for a heat pump but still the best for us. If it was wood frame enclosed and had R20 insulation it would not be an issue. We love the views out to yard, bird feeders and all.

[Mike Soaper]

FWIW HD's DoD has mini splits today, including some Mr Cool, no idea if they're good prices.

Special Buy Of The Day: Find The Deal Of The Day at The Home Depot (https://www.homedepot.com/SpecialBuy/SpecialBuyOfTheDay)

[Bill George]

My glassed in porch (12x20) the thermal pane has a R value of perhaps 3 and If I pull the drapes at night the Mini does an ok job down to -10 or so. But when the wind is blowing and no solar gain its a tough one. Daytime not a problem but its a poor application for a heat pump but still the best for us. If it was wood frame enclosed and had R20 insulation it would not be an issue. We love the views out to yard, bird feeders and all.

Well its -9 or -12 with winds now the wind chill is like -39F. Wind blowing directly into the outside unit and since the Mini has no back up heat, now its up to space heaters to keep it 45 F inside. I should have installed that Natural gas space heater!!

[Jim Becker]

Fortunately, it shouldn't stay that cold too long as the "bombe" is moving eastward bringing it's holiday joy to us "as we speak"...

[Bill George]

Fortunately, it shouldn't stay that cold too long as the "bombe" is moving eastward bringing it's holiday joy to us "as we speak"...

Yup its headed your way, it was in 2008 here in Iowa when it was that cold here before. My mini is starting to snap out of it now. Except for perhaps 5 days a year it does a great job and I knew that when it was installed.


EDIT What I did since the wind is bucking the discharge of the fan is pile up a few lawn chairs to block that wind. Seems to be helping it will work down to -10 but just can not handle a 30-40 mph wind blowing in its face! Air can still get out but the direct wind is slowed down.