Mini Split a second question

[Ron Citerone]

I didn’t want to redirect the recent post on 1or 2 mini split units so I posted a second thread. I kind of got inspired by the last thread. I think a single head 12000 BTU unit would work great in my cottage. I was on the internet today researching. I am now looking for some info from members who might know. How much can you save by installing a MrCool DIY over having a unit installed. Looks like Generation 4 MrCool 12k DIY is about $1700?
Thanks Ron

[Zachary Hoyt]

I installed that exact unit on the house about Thanksgiving. We haven't used it a lot yet, but we will in the spring when it's too cold for no heat and not cold enough to use the wood stove. The cost was about that, plus tax, as I recall, plus I had to buy a disconnect, surge protector, wire, etc. I was quoted well more than twice that amount just for the equipment to have a pro install a mini split, though I suspect that was a go away price. He didn't give me a quote for labor.

[Tom M King]

To do everything yourself with regular lines, it will take a couple of grand worth of tools and equipment, as well as a fair amount of studying. You won't make up any difference with one or two units. I bought all good equipment, and can do anything that a pro can, but we have a number of units, and no pro around here is as meticulous as I am. If you're only going to have a few heat pumps, I'd go with the Mr. Cool system.

At first it looks like you can get by with a few hundred dollars worth of equipment, but it's kind of like buying woodworking stuff after you get into it.

I don't know what you do when a Mr. Cool gives trouble. I can fix any problem with heat pumps or mini-splits, but I don't work on other peoples' stuff.

[Bill Dufour]

I bought a used name brand vac pump, flaring tool kit, tube benders from the bay for. under $200 delivered. It took a month or two to get good prices. I had a manifold gauge set for auto work.
Yellow jacket is one brand.
Bill D

[Bill George]

I believe with the Mr. Cool system its pre-charged line sets and connectors you don't need anything else to install. But for you DIY folks regular contractors will not work on a Home Owner installed system so you will need tools and knowledge then. Around here we have HVAC contractors who know about mini splits and what they are working on, unlike some areas of the country with unskilled self trained folks.

[Jim Becker]

What you see is what you get and what you need other than the electrical components that Zachary mentions. Very easy install. Just be sure ALL of the nuts on the line set's quick connects are fully tightened and you'll have smooth sailing. There are certainly some mini splits you can buy for less money, but to Tom's point, you need a bunch of tools and skills and access to refrigerant to install them and they often have no warranty unless you have a pro install them...which negates the idea of DIY. MrCool DIY systems are designed for DIY ;) and have an excellent warranty. They have a low cost extended service contract that covers labor and replacement, too. (OEM Warranty, as should be expected, is parts only)

BTW, $1449 for the 12K unit at Costco with free shipping.

[Allan Dozier]

Depends on variables as to your situation. I have never used the complete DIY units like Mr Cool but like was said above with the precharged line sets no special equipment is needed. The disadvantage of that is that you can't shorten them so look at your building and see what is feasible to efficiently run the pipes. If you have to coil them, coil them horizontally.

Do your research on the warranties. I may be wrong but I believe Mr Cool will warranty the DIY units for parts only, no labor. The two local pro contractors I know say they will be happy to look or repair DIY units just like if another contractor installed it but no warranty on their work. Check the details on any extended warranty offered by the seller. I know Lowes and Amazon offer them. Lowes says it covers all labor and parts or will replace the unit. Manufacturers warranty applies first. When I contacted Asurion used by Amazon they assured me that DIY is covered (however, I told them I had a 608 certification).

Having said all that you may decide like I did that you can replace most units for less than having them repaired. I just received a 36K BTU single head unit delivered yesterday. It was only $1800. It is to replace a unit that I didn't install in a building. The problem there is if the old unit still has refrigerant it must be recovered. I have a self powered recovery machine that you won't have so check to see if anyone would just come recover and what they would charge. The good thing about replacing a unit though is that the electrical hookup and holes in the wall, support base, etc. are already done.

[Doug Colombo]

We had a 18,000 BTU unit (Bryant) installed maybe 5 years ago at our cottage. Love the unit. It is almost silent when running, which is an huge difference from a thru the wall window type a/c unit. Installed, it was around $4,800. I looked at the Mr Cool units and almost pulled the trigger. What stop me was, at the time, it would only heat to I believe 5 degrees outside temp. As our place is in the upper lower peninsula of Michigan temps can get to 0 and below during the winter. The Bryant unit works up to -22 degrees before shutting down to protect the system. This allowed us to stop using the electric heat, which saved us $$. Also love the fact that it has WIFI access. Easy to increase temp before we head up so place is nice and warm when we get there. : )

I did see that one owner in the complex just install a Mr Cool unit but I believe he is only using it for cooling.

[Jim Becker]

Doug, current 3rd and 4th gen MrCool units go down to -13ºF for heating. Like any heat pump, they are certainly going to start to loose efficiency for heating at some point. On mine in the new shop building, that appears to be at around 20-25ºF, but my unit is also at the "space limit" for a 24K BTU unit because of my open ceiling. My normal shop temp is 66ºF and on the coldest nights we've had (very few...) it fell to about 58-59ºF but no lower. The shop is well insulated, especially relative to infiltration with the closed cell spray foam, but it's only about R15 in the walls and R21 up top; Houses are better for this because of the minimum of R30-R38, depending on geography for insulation up top.

[Ron Citerone]

Thanks guys! Sure is a lot to think about, luckily I won’t need AC till June at the cottage. I have to also look into some code issues.

I have watched several Utube videos and am amazed how straight forward these installations have become.

I don’t like the idea about the “Extra” cooling lines and how to deal with them. My unit could be right outside the wall from the inside head.

Thanks!

[Doug Colombo]

Doug, current 3rd and 4th gen MrCool units go down to -13ºF for heating.
Glad to hear this - I haven’t looked at them since we installed our unit. But this info will help me if we decide to put one in our garage at the house. And glad to hear Costco handles the units.

[Bill George]

Thanks guys! Sure is a lot to think about, luckily I won’t need AC till June at the cottage. I have to also look into some code issues.

I have watched several Utube videos and am amazed how straight forward these installations have become.

I don’t like the idea about the “Extra” cooling lines and how to deal with them. My unit could be right outside the wall from the inside head.

Thanks!

I purchased the shortest line set I could get and then just coiled them neatly vertically behind the outside unit. They are perhaps in a 2 - 3ft Dia circle. The Mitsubishi unit comes with flared line stub outs from the inside unit that extend through the wall and outside for easy hook up for the lineset.

[Jim Becker]

I don’t like the idea about the “Extra” cooling lines and how to deal with them. My unit could be right outside the wall from the inside head.



The standard line set with the units sold via retail are 25'. If you were to order from their captive Ingram (https://iwae.com/brand/mrcool/?series=518) company, you can "build" your unit with alternative line set lengths, but AFAIK, the shortest standard line set is 16'.

[Allan Dozier]

The last one I got from Lowes came with 16 ft line sets, the last from Amazon was 12 ft. But neither were pre-charged line sets.

[Tom M King]

Here is a list of most of the tools I use to shorten a lineset to just the right length. Otherwise, the coiling would look pretty good.

https://www.trutechtools.com/1926598

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
along with a 40 cu. ft. Nitrogen tank that cost a couple of hundred with a filled tank, and a little less than 25 bucks each refill

https://www.trutechtools.com/1885384

https://www.trutechtools.com/navac-nef6lm-cordless-power-flaring-tool-max-od.html

https://www.trutechtools.com/fieldpiece-vp67-runquick-dual-stage-vacuum-pump-6cfm.html

Actually this is not the torque wrench I use. I use one I already had and a flare nut crows foot. You still are best advised to use one though, so I'm listing this one.
https://www.trutechtools.com/navac-ntw1-digital-adjustable-torque-wrench-.html

I like a four valve manifold set so you can always have a vacuum pump hooked up to clear all the lines out without having to crack one open to the air even before charging a system. I also like ball valves on each line. Not absolutely necessary for installing a new line set, but you will need one for checking the charge in a system, and charging.

https://www.amazon.com/Yellow-Jacket-49968-Charging-Manifold/dp/B0036FAP5G/ref=sr_1_2?keywords=Yellow+Jacket&qid=1676738406&sr=8-2&ufe=app_do%3Aamzn1.fos.0566e4a0-c021-43c5-b0fb-9f56f724aabb

You can get by for less money, but I like to do something correctly once, and I get to deduct what I spend on tools.

The list is longer for charging a system, and troubleshooting the electrical parts.

[Ron Citerone]

So I take it the line set on mrcool is fairly easy to shape. Sounds pretty direct compared to a flare and evacuation for a first timer. I saw their video but wouldn’t mind hearing from a creeker who did it.😉

[Jim Becker]

The last one I got from Lowes came with 16 ft line sets, the last from Amazon was 12 ft. But neither were pre-charged line sets.

I was referring specifically to the MrCool DIY systems which the OP asked about.

[Jim Becker]

So I take it the line set on mrcool is fairly easy to shape. Sounds pretty direct compared to a flare and evacuation for a first timer. I saw their video but wouldn’t mind hearing from a creeker who did it.

Yes, it is, but you must take great care regardless, especially since it's pre-charged and expensive to replace. (DAKHIKT!) You do this slowly and carefully at the tails from the indoor unit and the last couple of feet at the outdoor unit. The larger coils of "extra" that would remain near the outdoor unit are less sensitive.

[Ron Citerone]

Yes, it is, but you must take great care regardless, especially since it's pre-charged and expensive to replace. (DAKHIKT!) You do this slowly and carefully at the tails from the indoor unit and the last couple of feet at the outdoor unit. The larger coils of "extra" that would remain near the outdoor unit are less sensitive.

Thanks Jim and others. DAMHIKT is how I learned a lot of what I know! I don’t mind learning from others who learn that way too! 😀

[Ronald Blue]

I'm not to concerned if I have issues down the road. I'm confident my HVAC guy will assist in repairing mine. He recommended I get Mr Cool. However mine weren't the DIY version. He came and shortened the lines and leak tested before charging the system. So no coils of excess line on mine. They worked great until it was cool enough that no AC was needed. I don't heat with them so I don't know how well that side of them work.

[Michael Schuch]

I have installed a Fujitsu single head mini split and a Mitsubishi 3 head mini split in my home. When I installed my Fujitsu many years ago I paid an AC tech to come out and do the final evacuation. He did NOT follow the Fujitsu directions (He also stunk of pot). They clearly stated to charge with Nitrogen, look for a pressure drop, evacuate then look for a pressure rise. He also charged me $350 for an hours work (several years ago). The 3 head Mitsubishi mini split I installed myself.

Tools:
vacuum pump - extra vacuum pump oil
YellowJacket eccentric flaring tool made for R410 flares.
Gauge / line set.
Nitrogen tank - gauge and fitting adapter for gauge set.
Nylog flare sealant (AC guy had never heard of it).

I skipped the recommended expensive micron vacuum gauge (so did the AC guy).

I will never use an overpriced under trained AC company guy again. I also walked my boss through installing his Mitsubishi mini split. It took him 2 tries to get a good seal on one of the flare connections but it has been working fine for a year now. My boss is smart but doesn't have a lot of home improvement experience.

When I do a pressure test then vacuum leak test I let both sit over night... which gives me much more confidence than the 45 minutes the AC tech waited!

[Tom M King]

I also pressure test with Nitrogen overnight and note the temperature of the lines both days to allow for any difference in pressure. I don't skip, or skimp on any tools. I replaced one lineset in a rental house that leaked down as you watched the gauge on the nitrogen regulator. It was leaking inside a wall that I didn't want to tear into.

I left the vacuum pump on my truck AC system too long one time, and compromised an O-ring, so I want to know how much of a vacuum I have on something.

[Bill George]

Tom you are doing things the right way!

I installed my Mitsubishi mini split on recommendation of my son who is service manager for a large Union commercial HVAC/R company. They just do not have issues and that's what he wants. I worked in the exact same business for many years and we were taught the correct way to do the work.

I have had limited experience with China made refrigeration systems and it does not hold up to the Japan based, designed units. The stuff I did run into suggests they are not that great at brazing and final leak detection.

[Thomas Pender]

Missed this earlier. I have significant HVAC experience from years gone by and with friendships, etc. One of the rules of thumb is that while the manufacturer is important for quality, the experience and skill of the installer is more important - as important as 75%. So, when I wanted a mini-split for my shop, which is in my basement, but on grade with my backyard and has two large garage doors, I hired the most reputable pro in our area to install the highest rated Toshiba unit. It has been a joy. Keeps stuff warm in the winter and not much of an issue in the summer since I have some walls that stay a fairly constant 55 degrees. What I am saying is I would never and I mean never, install my own Heat Pump HVAC system (including mini-split) unless I did it for a living. I am sure many will disagree with me and that is fine, but the warranties and quality you get bring peace of mind and longevity in my experience.

[Jim Becker]

I agree with you in many principles, Thomas, but relative to warranties, my "designed as a DIY system" for the shop has one of the best and longest warranties in the business. That part really comes down to what's in the fine print. Many systems that folks DIY actually do not have a warranty if a DIY install is done...it's a "gotcha" that gets missed during the buying process. That might be worth the risk for a detached workshop or garage system, but probably isn't the best idea for one's home.

[Tom M King]

Here is the quality we get from Pros around here. I ended up replacing this old line set. The house is old enough that I'm sure it was an R22 system to start with. We own it as a rental house now. What odds do you give that they flushed out the old lines. The old lines were in the wall behind brick. The vapor line was leaking.

Notice the crimp from hand bending the line, and the brazed joint that it looks like the one piece was "swaged" up with the little end of a ball peen hammer.

My other experience with a pro install was for a mini-split that we had to get in on very short notice for my 104 (then) year old Mother to move in with us. The system leaked, and when he came back to put in the half pound of 410a that had leaked out from his install, he charged me $400.

I do it myself for piece of mind and longevity. You don't know what you'll get when you call a "pro" around here. I have known some good ones, but they're all retired or dead now. I do it myself also out of desperation to get something done right, and for the quality of good work.

That 3/4" line was crimped enough to almost completely close off any flow of even vapor. A couple of other examples of pro work thrown in. One duct was heating and cooling the attic. The electrical line was soldered onto a connector that was really too small for the wire size-solder melted, circuit failed.

[Bill George]

My students in our HVAC/R program used to laugh at the pictures of stuff that was done in some of those areas. I had one take a spring break in Georgia and we all got a kick out of what passed for skilled labor down there. Most of the shops up here are either union or NATE certified trained in non-union shops. Need to be trained in the mini's and other complex systems. We also taught computer and CAD skills as part of the Program.

The cr@p posted above would get you fired!!