Sizing a unit for my garage

[Stefan S]

Hi all, curious on how best to size a unit for my garage. I’m going to install the Mr. Cool diy mini split unit but I’m not sure what size I should consider. I’ll probably keep it kinda high and then turn it down when I’m out there in the evenings. I wouldn’t want it to take too long to cool but I don’t want to undersize it either. Thanks for all your help!

Size 24’x24’x9’2”
Location: Austin Texas
Insulation: r13 in walls and ceilings installed by me a year ago
Walls: OSB plywood caulked seams
Doors: two (2) 8’x7’ garage doors with r7 insulation and one 30” man door
Windows: no windows
Compass: garage doors face south moderate shade provided by trees

Couple pictures for reference:

 

[shade]

Show more pictures of the garage!
Do a load calc but I bet a 24k will be fine but I love quick cool down especially when I bring cars in and out. 36k may also be good!
Also letting the units run isn't a big deal they are super efficient.
I have 2 24k units that run all day and night - needed I run IT equipment but it came out to like $15 or $20 a month on my bill

 

[Stefan S]

Show more pictures of the garage!
Do a load calc but I bet a 24k will be fine but I love quick cool down especially when I bring cars in and out. 36k may also be good!
Also letting the units run isn't a big deal they are super efficient.
I have 2 24k units that run all day and night - needed I run IT equipment but it came out to like $15 or $20 a month on my bill

Not a bad idea about letting them run - I didn’t realize they were quite that efficient!

Here’s a couple more of the garage

This is where I started

 

[Stefan S]

Where can I find a good load calculator?

 

[nadogail]

IMHO, I would get independent opinions from more than one well respected local dealer.

 

[shade]

Where can I find a good load calculator?

https://www.ecomfort.com/stories/1439-What-Size-Mini-Split-Should-You-Buy.html

If you have a dealer come by they are going to try and bend you over.
Install a DIY is pretty simple. Running electrical took the most time.

 

[Stefan S]

https://www.ecomfort.com/stories/1439-What-Size-Mini-Split-Should-You-Buy.html

If you have a dealer come by they are going to try and bend you over.
Install a DIY is pretty simple. Running electrical took the most time.

Yeah I’m more of a diy guy who does everything myself

I ran the detailed calculations and it returned the attached for the cool and heat loads. Based on this I’m thinking an 18k unit will be perfect. I work on bikes motored and pedal mostly.

Does this seem correct? I rated my insulation as fair.

 

[Stefan S]

Does 18k sound right?

 

[nealric]

Does 18k sound right?

18k will likely do the trick, but I'd go for a 24k if you aren't going to leave it on. It will get it down to temp more quickly. Mini splits don't have the short cycling issues of traditional systems if you are a bit oversized.

Also consider sun hit. If you have shade, you might be able to get away with less.

 

[dcg9381]

I'm in Austin. I have a 2400 sqft building. Moderate insulation (3-3.5" foam). Building is "high ceiling" - at 16' eves and has big poorly-insulated doors. I cool it with 2 x 24K units and they do fine, although most of our hanging out is just in one end of the building. If it's under 90 degrees or so, we just run one unit.

I don't think you'll find that it's cost efficient to leave them running, but I could be surprised. Lots of garage opening / closing and perhaps the head sync from the cars. Running our two units on/off probably adds $70 to our electricity bill monthly.

For me, 24k was the right price point with capacity.. I think 2 x 24k were at or slightly less expensive than moving to a 36k.

I've installed 18K units in 600-700 sqft, as long as they are insulated reasonably, that'll get it done too.

For your application, it really depends on how fast you want to cool it down. The load calcs assume that you're cooling it constantly and that's not necessarily how you use it for garages.. And these units throttle back nicely once things are cool.

 

[Stefan S]

Thanks for the advice everyone! I don’t park cars in this garage just motorcycles and with the man door I’m not opening the garage doors too often so I’m hoping the 18k will do well.

 

[shade]

should be fine. Just insulate as best as possible

 

[yeldogt]

The space is just over 500sf -- when you did the load what was the design temps?

You do typically want to at least maintain some level -- just to keep humidity down