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/pr...ies/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/bl...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).