Shop heating and cooling

[Jacob Mac]

I live in Kansas City and work in a garage with 11 foot ceilings, a single and double bay, no windows, one wall is exposed to the outside, the other two butt up against the house, and the garage doors face north. Everything is as insulated and sealed up as I can get it.

Our temperatures easily range from 0-100 with lots of humidity. I have a dehumidifier which runs constantly from spring through fall and some during the winter.

I've been hesitant to add any heating or AC because I was unsure if I was staying in the house. But it seems like I will be, and the weather is such that I just don't do any woodworking for several months out of the year because it is too uncomfortable in the shop. It is either freezing or I'm sweating all over my tools in a garage that is over 105 degrees.

I'm thinking of installing a mini split. Good idea? Is there a better one? Recommendations as to brand, size? Installation tips?

[Jim Becker]

Mini Split was one of the best decisions I made for my shop a year and a half ago...it's always comfortable and the impact on our energy bill has been almost unnoticeable. (full disclosure...my shop is reasonably well insulated, too) Mine is a Daikon which is a major brand that often sports other names. Size has to be determined by your square foot figure and ceiling height. I have about 680 sq ft and the 18K unit keeps it exactly the way I want it to be, both for heating (current) and cooling (summer). I did all the prep work for electrical which cut down my installation cost. With few exceptions, the units do need to be charged/final-installed by a qualified HVAC resource, both because of training and having the correct gear to do the work. Sometimes you can find someone to help via "moonlighting" if you want to keep costs down. My installation was by the same firm that has my business for both HVAC units in the house and who have become "friends" over time. So I got a bit of a break on the deal, especially since I had all the site prep completely done, including the wall penetration and exterior site leveling. It was a very quick install for them. I later installed the IP based interface module myself so I can control the system from my iPhone.

[Kevin Jenness]

I recently had a Fujitsu Halcyon 18,000 btu ductless heat pump (mini-split) installed in my 1100 sq ft shop. It's doing fine in the current 10-30 degree weather. This is a model designed for low temperatures and is supposed to function down to -15, although the efficiency drops a lot. I had it installed by a small outfit that does nothing but heat pumps, and the owner/installer said it was very important to pull a deep vacuum on the system and monitor for leaks for some hours before charging with coolant.

[Jacob Mac]

Best as I can tell, my garage is about 650 sq ft. Seems like 18k should work based on conversations and research.

Interested in hearing other people's experiences. Pitfalls, advantages etc. If I had a window, I wouldn't be interested in a mini split. But no way my HOA approves installing a window with a window unit.

What is a fair ballpark for installation? The minisplit would be about 6 feet from the subpanel, and I just run conduit on the wall. So electrical would be super easy.

[Jacob Mac]

Mini Split was one of the best decisions I made for my shop a year and a half ago...it's always comfortable and the impact on our energy bill has been almost unnoticeable. (full disclosure...my shop is reasonably well insulated, too) Mine is a Daikon which is a major brand that often sports other names. Size has to be determined by your square foot figure and ceiling height. I have about 680 sq ft and the 18K unit keeps it exactly the way I want it to be, both for heating (current) and cooling (summer). I did all the prep work for electrical which cut down my installation cost. With few exceptions, the units do need to be charged/final-installed by a qualified HVAC resource, both because of training and having the correct gear to do the work. Sometimes you can find someone to help via "moonlighting" if you want to keep costs down. My installation was by the same firm that has my business for both HVAC units in the house and who have become "friends" over time. So I got a bit of a break on the deal, especially since I had all the site prep completely done, including the wall penetration and exterior site leveling. It was a very quick install for them. I later installed the IP based interface module myself so I can control the system from my iPhone.

If you don't mind me asking, what is the seer rating on your minisplit? How big of a consideration was that when you made your purchase?

[Kevin Jenness]

To follow up, cold weather is here, -7 F this morning. The shop and house, both with the same 18k unit were nice and warm. I will be running the woodstoves today as the efficiency of the heat pumps will be low, but it's nice to know that they work at this low temperature.

My Fujitsu mini-splits claim "up to 23 SEER". They have a lower output range in the same series, up to 15k btu, that claim up to 33 SEER. I would guess that the efficiency rating falls with outside temperature as more energy has to go into keeping the compressor coils frost free. The brochure says that rated heat output is maintained down to +20 F. I suspect that you could use a smaller unit than 18k, but you should have a competent person spec the btu rating.

My heat pumps cost $4100 installed per unit. That included a $400 credit from the state energy efficiency agency, and I stand to receive another $400 rebate from the power company, so it's worth checking into that.

https://www.fujitsugeneral.com/us/products/split/wall/rls3h-series/index.html

[Jim Becker]

If you don't mind me asking, what is the seer rating on your minisplit? How big of a consideration was that when you made your purchase?

SEER is 20 on my unit and it's rated down to -5ºF. MiniSplits tend to be more efficient than the typical heat pumps installed in homes, although the latter is certainly getting better. I'm really amazed at how efficient mine is. They are not inexpensive at all, but the level of comfort that comes from having reliable and consistent heat and AC when they are appropriate makes working in the shop a whole lot more pleasant. I used to use resistance heat in the shop and while it warmed things up ... eventually ... it was way too expensive to run other than when I was actually out there. That means also having resistance radiant to take the edge off until things warmed up...meaning more energy cost. Now, I leave the unit set at 64ºF full time and kick it up a little before I spray finish (water borne) so things are in the proper range for the finish. It takes a surprisingly short time to come up to temperature. AC in the summer is similar. I leave it at 76ºF for the period of time that AC is necessary. With the insulation I mentioned as well as the units efficiency, it's a pleasure to use and very economical.

BTW, the wiring for your mini-split has to go outside to the outdoor unit. The inside unit is powered from that. So even though you expect to install adjacent to your panel, your conduit will transition to the outside for the 240v power. You'll want to install an inline surge protector as part of the setup and you'll also need a disconnect on the outside near the unit. There will be a requirement for a hole in the 2.5", give or take, for the lines and electrical between the external and internal units, but that cannot be placed until you physically have the system on-site so you have the mounting template to locate things.

[Jacob Mac]

I wired my shop myself and then had it inspected to insure I was code compliant. But that took forever and I obsessed over every little thing. I think this go around I will just pay for a competent tradesman to install it and enjoy the heat immediately.

[Mark Daily]

You might find this information useful for your BTU calculation:

https://mspplumbingheatingair.com/blog/what-size-ductless-heat-pump-do-i-need

[Jacob Mac]

I spoke with a contractor and for a Mitsubishi 18000 btu minisplit, he said it would be between $5500 and $6500 for everything.

Gonna keep looking for estimates/other systems

[Kevin Jenness]

That seems quite high. I got quotes from $4100- $5000 here in VT.

[Jacob Mac]

That seems quite high. I got quotes from $4100- $5000 here in VT.

Seemed really high to me, too. I like the idea of getting a good minisplit. And I don't mind paying a fair price for someone's labor. But that seems like it might be too high.

I will keep asking around, or just figure out how to do it myself

[Dan Friedrichs]

I bought a 9k BTU Pioneer 22 SEER heat pump from https://www.pioneerminisplit.com/, for $800 with free freight shipping, and it showed up in ~4 days. Installed it myself in an afternoon. Obviously you need to be capable of wiring, etc, but if you're handy enough to do something like change brake pads and rotors on a car, this certainly wasn't more technically complex (just as a frame of reference that I imagine many people would be familiar with).

I agree with Jim - it's one of the best things I've done. I used to deal with emptying a dehumidifier (and putting up with the ~500W of "extra" heating it was putting into the garage in the hot months) and used a 5kW resistance heater in the winter (which I always felt guilty using given it cost so much to run). Now I just leave the minisplit running all the time...

[Jim Becker]

For reference, my unit was under $4K including the installation by trained folks. I paid a bit less for the labor because I did all the site prep and electrical as I mentioned previously prior to their arrival and, um...paid cash. ;)

[Bob Riefer]

I also installed a mini-split in my shop recently. We moved it from our sunroom (which needed a more powerful unit) to the shop.

I keep it set at 61 degree F in cold months and at 80 during the hot months... When I'm heading out to do work, I just bump it up or down and hit the "turbo" button, and I'm plenty comfortable by the time my first cup of coffee is done.

Note... Even in the summer when it's really hot and humid out, the 80 degree setting makes it feel wonderful in the shop. No humidity is the main win. And getting from 80 back down to low 70's takes no time at all.

I've also noticed on the various online marketplaces (CL, FB etc.) that lightly used mini-splits are popping up for sale at good prices. Some, I see are from HVAC companies - I haven't looked into the deals closely, but a buddy of mine is HVAC professional and he told me, that like my sunroom situation, there are numerous situations where undersized system installs result in re-work later (either due to change in the space, poor calculation by the technician etc.). His opinion was that he wouldn't shy away from a used unit if the situation was right (i.e. from a reputable HVAC installer).

[Jacob Mac]

Seems like 2k for installation with all of the necessary extras for installation is what the market around here is set at.

For those who did went the diy route, it seems like you would need aDHP vacuum and some other specialty tools to do the install. Did you guys buy the tools, rent them? Forego the vacuum altogether?

[Jim Becker]

Unless you buy one of the few units that have the lines pre-purged (Mr Cool brand I think) you can't avoid the need to do or have that done as your setup. You may be able to find someone who moonlights to take care of that. 'Not sure if the necessary gear is available in rental places or not.

[Dan Friedrichs]

Yikes, that's steep...

I bought a cheap vacuum pump with gauges on Amazon for ~$70. Worked great. I think the only other tool I bought was a tube flaring tool (I cut my lines to fit, exactly, so needed to re-flare one end. I think most online sellers also let you choose between several lengths of tubing, so depending on your installation - and willingness to coil up extra tubing - you may not need to bother with that).

[John Stankus]

I bought a pump and gauges as well. Toughest part of the install is making sure the flare joints don't leak. You can get preflared tubing in various lengths. acwholesalers out of Florida is where I bought my unit (Mitsubishi Mr. Slim). Daikon is also supposed to be a decent brand.

Probably one of the most cost effective paths is to do the install yourself and get someone out to do the commissioning.

Oh...the power goes to the outside unit, and is feed to the inside via the control cable. (remembered you mentioned the inside unit would be near the panel)

[Dan Friedrichs]

Probably one of the most cost effective paths is to do the install yourself and get someone out to do the commissioning.

That's a good idea. 95% of the install is just mounting the units, running the wiring, drilling a hole for the tubing, etc. You could probably hire an HVAC guy to come out and vacuum the lines down, flare the tubing, etc.

(That said, flaring the tubing was probably the most technically challenging part, and it wasn't that bad. It needs to be fairly perfect, but it's just about doing good work - make sure the tubing is cut nice and square, completely debur it, clean it up with a file so you have a nice square and flat surface, and be consistent with following the flaring tool instructions - and it's easy to get good results )

[Jim Becker]

Many HVAC "firms" will not do the commissioning on a unit they did not sell and install, but as I noted earlier, individual HVAC technicians have been know to "moonlight" for small jobs like this. That's likely who needs to be found. I got lucky in that I'm personal friends with the HVAC company's owners and we worked a deal for the unit and the parts of the installation that were not for me to do.

[Jack Frederick]

I agree that a mini-split heat pump (mshp) is the way to go, I am sure you are best off with the major brands. In my case that is fujitsu, Mitsubishi, Daikin and I guess I can add Gree to that list now too. There are a million brands. Stay away from the Bryant, Carrier, Trade, etc units as they are just private labeled products. NEVER use the flares on the line set as they are provided. They are made to keep the flare nuts on and generally will not see the kind of pressures you see with 410A in heating. If you do install it yourself, do a nitrogen purge first. Buy a really good flaring tool. Years ago I bought the Ritchie (yellow-jacket) version. I did one flare and went over to the tool box and took my 40 yrs of plumbing flaring tool and threw it in the trash. I think you are better off with a pro install. Look on the manuf web-sites at the dealer locators and confirm in your meeting that they have indeed been to the factory trainings. Install it yourself and be prepared for a nightmare dealing with the factory if you have issues. I represented Fujitsu in a six state area for 14 yrs. I heat and cool my home with mshp's They are tremendous technology and much more efficient that the unitary stuff. On the seer ratings, when the 410a units first came out we were hitting 25/6seer. I asked the Japanese engineers if that was accurate. They said,"no, they are actually higher, but the american testing agencies don't have an effective test for modulating equipment." You won't believe how well they work. If you have a pro install make sure they teach you how to remove the entire cabinet. Do not put it to high on the wall. 7-8' is it. Get it to high and with the cabinet removed you have a heck of a time cleaning the back of the coil. Also have them show you how to clean the blower wheel. I have two in the house that I have to clean and I will be stunned and amazed at how well they work once I unload that small diameter fan. Happy Heating.

[Steven Wayne]

I have two Pioneer 24k minit splits. They are four years old and have been serving me well. Pioneer's newer, higher SEER rating units heat to a lower outdoor ambient temperature.

[Jacob Mac]

I agree that a mini-split heat pump (mshp) is the way to go, I am sure you are best off with the major brands. In my case that is fujitsu, Mitsubishi, Daikin and I guess I can add Gree to that list now too. There are a million brands. Stay away from the Bryant, Carrier, Trade, etc units as they are just private labeled products. NEVER use the flares on the line set as they are provided. They are made to keep the flare nuts on and generally will not see the kind of pressures you see with 410A in heating. If you do install it yourself, do a nitrogen purge first. Buy a really good flaring tool. Years ago I bought the Ritchie (yellow-jacket) version. I did one flare and went over to the tool box and took my 40 yrs of plumbing flaring tool and threw it in the trash. I think you are better off with a pro install. Look on the manuf web-sites at the dealer locators and confirm in your meeting that they have indeed been to the factory trainings. Install it yourself and be prepared for a nightmare dealing with the factory if you have issues. I represented Fujitsu in a six state area for 14 yrs. I heat and cool my home with mshp's They are tremendous technology and much more efficient that the unitary stuff. On the seer ratings, when the 410a units first came out we were hitting 25/6seer. I asked the Japanese engineers if that was accurate. They said,"no, they are actually higher, but the american testing agencies don't have an effective test for modulating equipment." You won't believe how well they work. If you have a pro install make sure they teach you how to remove the entire cabinet. Do not put it to high on the wall. 7-8' is it. Get it to high and with the cabinet removed you have a heck of a time cleaning the back of the coil. Also have them show you how to clean the blower wheel. I have two in the house that I have to clean and I will be stunned and amazed at how well they work once I unload that small diameter fan. Happy Heating.

Thanks Jack. I tend to think that with the right tools and training that I could install it myself. But I have neither. And I don't have a lot of natural aptitude for this. I definitely work hard for whatever modicum of skill I have with this kind of thing.

An HVAC tech quoted me 3200 all in for the base level 18k gree model. Not sure that is the model I want. He said he would install whatever, it will just bump up the cost.

[Jacob Mac]

One tech told me that 12000 btu was enough and priced accordingly. The next told me no way I should go below 18000 btu and that I could never go too big with a unit so long as it has some type of variable speed.

Given an insulated 30x20 garage with 11 ft ceilings, in an environment where we go between 15-100 degrees seasonally with colder possible, what is the conventional wisdom? 12 or 18? Does it matter? I always heard that too big of a unit would cause issues.

[Jim Becker]

My shop is similar sized (~23X30X8) and I was told clearly that the 18K BTU was the correct size for my space. With your higher ceilings, I cannot see the 12K BTU being adequate at the extremes of your weather swings unless you have an incredibly well insulated building. 18K BTU will not be too big, IMHO.

[Steven Wayne]

Personally, I would go with the 18k. I've noticed my splits work really hard when the outside temps drop. I have a 24k in 30 x 40 with 12-14 ft ceilings and I wish I had the 36k unit in here when it's really hot or really cold outside.

[Jacob Mac]

Thanks guys. I think I'm going to go with an 18. Seems to be the consensus outside of the two quotes.

[Darcy Warner]

I pump about 400k btus into just over half my shop, balmy 55 degrees in there.

[Jack Frederick]

Your contractor saying that you cannot go to large is not the right way to think about it. I have been selling modulating heating and cooling equipment since '91 and what I have learned is that what is most important to you is not how high it will go, but how low. Oversizing heating equipment, cooling is different, is just so common. Most central systems are about double or more than what is really required. A contractor does a manual J. It says, "X". He then considers the crew who built the place, doesn't believe the number and if a 50 kbtu is sized you will end up with a 75 or 100. He then tells you you will never be cold. Also, the manual J is sized to heat the place at "design conditions." DC is the coldest temp you are likely to see in your area. If you look at the weather statistics you are at design condition less than 2-3% of the heating hours of a season. So you end up oversized by design and then selection. In your case I would go with an 18. I generally push sizing with mini-splits on the low side as I have found they consistently exceed expectations. In a shop environment you will likely not maintain temperatures. The few extra btus will get the temperatures up a bit quicker an the low end of an 18 isn't to far off the 12. I know a contractor who does only Gree's and has good luck with them. Have the contractor show you how to remove the cover so you can clean the coils and the fan. In a shop environment simply cleaning the filters is not enough. I kinda go all in on that cleaning...when I do it. I tape up the wall with poly sheeting and gather that into a garbage can that holds water, Then carefully, once the entire cover is off, vac the face of the coil being careful not to touch the fins. It is then time for a bath on the coil. Once the fan blades get dirty your performance drops off. Some people will remove the fan. I have not, but it is a real pitn to clean the fan in place and do it effectively. The curved blade fans really pick up the dirt. Once you get the crap off the leading edge of the blades you will not believe the difference. I say this as I look at the two evaps I can see in the house and having looked at them yesterday I HAVE to clean them this next week when my wife is out of the house for a few hours.

[Jacob Mac]

I am going to go with an 18,000 Daikin. Bid for that was almost identical to the Gree but better warranty at the very least. Thanks everyone for the advice, it made making an informed decision much easier

[Jim Becker]

Sounds like you chose the same unit (or a close relative, depending on model numbers changing since March 2018) that I have and I am COMPLETELY pleased with mine. Daikon is a big player...with other nameplates on their stuff, too.

[Tom Bender]

If space permits, plant a couple of sugar maples south of your shop. Sure it's a long game but in time you will love them.

Sugar Maples because they are more wind resistant than Oaks and provide better shade. Also, the leaves are the easiest to rake.

[Jacob Mac]

I got it installed, and even though we have had an unseasonably warm winter this year, I think this is my favorite shop upgrade to date.

[Jim Becker]

I think this is my favorite shop upgrade to date.
Not quite two years later...I still feel the same way about mine.

[michael dilday]

I have a 18k window heat pump - heats and cools great. Has a thermostat so I can set the temperature. Costs around $800 a few years ago. Got it at Home Depot.

[Paul F Mills]

I have been considering a mini split or a window unit in my garage shop. The temperature fluctuations are doable but is pain. My main concern is the high moisture (13-16% on some wood that has been cut for over 10 years and in my garage for at least a year, previously stored in an unconditioned basement across town) and I am hoping a conditioned garage would help that. Everything except the door where I would install the window unit is well insulated. I would replace the door or add insulation to it.

Spending $800-1000 on a window unit is an easy decision, $3000 plus on a mini split is harder. Other than Michael, has anyone done a window unit successfully?

[Jim Becker]

Paul, aside from ease of install, the difference in cost between the window unit and the minisplit revolves a lot around energy efficiency. The latter is typically 20+ SEER these days. Both are good solutions, however, and stabilizing the RH in your workspace may very well help keep your material more consistent over time, not to mention make working in there more comfortable, especially given increasing temperatures which make humidity even more uncomfortable.

[Jim Andrew]

Just looked at window heat pumps, and found Amazon has a 25000 btu window unit for 729 shipping included. Hard to find the seer on these units, but would be easy for a diy guy to install one, except it is pretty heavy.

[Jacob Mac]

I would have used a window unit, but it just wasn't feasible in my situation.

[Paul F Mills]

Thanks for the input Jim Becker. While I would love to save on the unit cost, long term operational costs of the window unit would probably be significantly higher than the mini split. If I really was to keep the humidity consistent, I would need to run it all the time. The biggest issue with that is that my workshop is in my garage and is how we access the house daily. I was working on a shade structure by the pool today with the garage door open, so I would need to shut if off during times like that.

[Jim Becker]

Yes, "garage" complicates things if it gets used as a garage and the big doors are opened constantly. Humidity control really is best with a more constant approach. An HVAC system can get the temperatures up or down relatively quickly when they are sized correctly, but it still takes time to deal with humidity. Opening a big garage door for even a few minutes could result in a complete exchange of the conditioned air with non-conditioned air and you're back to square one. The logical solution is...stop using that space as a garage! LOL

[Darcy Warner]

Yes, "garage" complicates things if it gets used as a garage and the big doors are opened constantly. Humidity control really is best with a more constant approach. An HVAC system can get the temperatures up or down relatively quickly when they are sized correctly, but it still takes time to deal with humidity. Opening a big garage door for even a few minutes could result in a complete exchange of the conditioned air with non-conditioned air and you're back to square one. The logical solution is...stop using that space as a garage! LOL

Try having 8 giant overhead doors, 4 of those being docks, it's an exercise of just paying that stupid gas bill.

[Paul F Mills]

I guess I have three options:
-build a workshop adjacent to the house
-build a new house with a three car garage (what I really want to do)
-convert the downstairs bedroom to a wood storage and finishing room, while doing the dusty work in the garage.

[Jim Becker]

Paul, that last one might be the most practical short term solution as that room is likely conditioned space. It will at least help maintain reasonable moisture content in your stock. The other two are understandably longer term goals. I kinda worry about this very thing if we decide to "downsize" in a few years...the shop is really important to me.

[Paul F Mills]

We downsized a few years ago from 4000sf to 2800 sf. I really want to downsize to 1800sf but with a larger garage.

I have prelim approval from the wife to use the room for wood storage. I am still going to condition the garage, probably a window unit to start, and see how it goes. I may be able to divide the wood storage and have more recently cut wood in the garage and ready to use in the house, and move wood around as needed.

[Jim Becker]

Keeping the material in the conditioned space and having a cooling unit in the work area while you're in there, um...working...should make for more comfortable enjoyment of your woodworking.

We're currently at 4200 sw ft plus my shop building. The real workload is maintaining the large property--not the mowing, but the weeding of the landscape, etc. I'm just not very good getting down on my knees anymore. Honestly, once our younger graduates from Penn State in 2021 and our older daughter "hopefully" becomes more independent and gets her own place in town (she has psychological and minor intellectual disabilities) we really don't "need" such a large home. It will be a really tough choice, however, because we really love this place and have made it our own over the past 20 years. And yea...the shop. :)