unisulated garage - undersized mini split?

[tedzap]

I am thinking about installing a mini-split in the garage. My winter temps sometimes dip to single digits, but is usually 20+. My summer is fairly mild, but I have humidity issues. I am in southwest Virginia.

I have had a few contractors out to look, and frankly, they are out of their mind. $7k to install a unit I can buy for under $2k.

The two "quotes" talked about an 18k and a 24k unit, and I am thinking about doing it myself. Toward this end I am acquiring tools, have a gage set, micron gage, and a vacuum pump. Need a good flaring tool and some nitrogen.


The garage is mostly uninsulated 24x32 with 10' ceilings, and there isn't much I can do to help that... it has an 18' x 8' single pain glass garage door that came out of an old gas station. Insulating the other walls isn't going to help much. The ceiling is insulated, there is a finished room above.


Load calcs have proven difficult as the online ones I have found give wildly different values. Probably something to do with 144 square foot of single pane glass.

If I have modest temperature requirements, would the 18k be sufficient? I would be happy with 60 degrees through the winter. I would leave it running at a low temp 24/7 if this makes a difference.

I know this is hard to estimate without seeing it, but I don't trust the people who gave me quotes. Anyone been in a similar spot? Recommendations?

TIA,
Ted

 

[BoostAddiction]

I am in northern VA, but have an insulated garage of around 840 sq ft.

With a 2 ton minisplit, my garage is always temperate. I only run it when I need heating or cooling, and I never have it on when I'm not in the garage working, so it is never on overnight, for example.

It is a great addition to the garage, and makes it a pleasure to work there. I'd do it again in a minute if I had to.

I found the same great price disparities, so I bought mine via the web, and had out local installer guys do the install. Saved a couple grand, overall.

 

[CNGsaves]

Why not post details on proposed mini-splits you are considering??

Big question . . . why jump straight to mini-split and not pursue insulation and other finishing steps first??

I'd vote to follow normal garage finishing steps - - - rough electrical, any in-wall like internet/CATV/phone/security & airline systems (copper or black pipe steel), insulation, sheetrock, and finally heating/cooling system.

For electrical, plan ahead for a compressor 240volt run, welder ??, outlets, etc.

Let's see pics of garage and explain if finished room above garage is "living space" or just garage storage. Insulation of garage walls (garage door) will also greatly help maintain temps of that upper room if garage is kept at better temperatures.

 

[tedzap]

Why not post details on proposed mini-splits you are considering??

I am considering Mitsubishi, Daikin, and Fujitsu current units.

Big question . . . why jump straight to mini-split and not pursue insulation and other finishing steps first??

As I said before, the 18' garage door is single pane glass. The other three walls are estimated at R-8, with siding and drywall. If I were to remove the drywall and insulate better, the overall room heating load would be little affected... the garage door is the driving force in the overall load of the room.

I'd vote to follow normal garage finishing steps - - - rough electrical, any in-wall like internet/CATV/phone/security & airline systems (copper or black pipe steel), insulation, sheetrock, and finally heating/cooling system.

Thanks, I will keep that in mind.

For electrical, plan ahead for a compressor 240volt run, welder ??, outlets, etc.

The shop has 200A service into it, welder, lathe, mill, bandsaw, etc.

Let's see pics of garage and explain if finished room above garage is "living space" or just garage storage. Insulation of garage walls (garage door) will also greatly help maintain temps of that upper room if garage is kept at better temperatures.

The room above the garage is finished living space. I am not willing to cover the glass of the garage door. I am not willing to replace the garage door.

 

[CNGsaves]

Sounds like you actually have empty stud walls covered with sheetrock . . right?? You could insulate those with blown insulation by drilling holes in top of each wall cavity.

That oversize old glass-pane garage door sounds pretty cool. I was thinking just a row of glass, but apparently every single section of entire door is single-pane glass. Let's see a pic !!

With the size of your garage and heat/cooling losses (ie door, walls, ceilings, etc) then I'd suggest large mini-split. Proper sizing is important, or you'll always be cussing the system. As alternative, did you consider using hanging natural gas heater and a seperate large window air conditioner??

Others here on GJ have installed their own mini-split and often they arranged for HVAC pro to pressurize the system once the rough install was done. Use the Search / Advanced Search near top of website in the black line.

Good luck. Hope you at least share pics of your unique glass garage door !

 

[Charles (in GA)]

I think you are way underestimating what insulation will do for you. Yes, the glass will lose heat, but well insulated walls will make a huge difference. Probably the difference between wasting money heating at all (no insulation) and being able to heat it.

Charles