Yet another mini split thread

[Norcrawler]

So to start things off. I've done hvac for about 10 years. Mainly service but some installs aswell. We very, very rarely install mini splits. But I've done them in the past for side work and what not. Install is obviously not the issue here. I'm curious on sizing and what others have ran. You can't exactly load calc something like this due to a garage door that may open and close. That's really my only question, is regarding the door that will periodically open and what others have used to keep up.

My setup currently is a 2 car, 380 sq ft garage on a concrete slab that's tiled. Fully insulated r11 walls (3 walls are exterior) with a insulated ceiling to around r49. The door is also Insulated.
I'm located in Sacramento CA. Our summers are hot with 100+ degree weather. Winters can get as low as 30s at times but it's usually around the 40's.

Some others from a hvac group recommended a 24k. I think this would probably be extremely oversized. Even when it throttles all the way down it could still be too much on a not so warm day. I'm thinking a 15k would be a better overall unit givin the small sq footage with a minimum cooling btu of 3100.
Any input is appreciated. Thank you

 

[ticklechicken]

With that much insulation, I was going to suggest 12k, especially if your garage door is either insulated or facing north.

 

[theoldwizard1]

It is a lot more money but two smaller units will have much better SEER. At would recommend at least 15K. Playing with the thermostats, you should be able to get them to stagger, but most min-splits can also master-slave.

 

[Jinks]

Mine is a slightly over sized single car garage that I opened an existing guest bedroom into. It's under a second floor. The east end of the garage, the south wall, & the west end with the garage door are not insulated. Everything else is part of the house insulation. Total sq. footage is about 20 sq. ft. bigger than a two car garage.

I put in a 12000 BTU mini split, A/C only. It cools the shop into the 70's on 100 degree days. I have a ceiling fan in the garage bay & the shop bay that circulates the air. I only open the garage door if I need to move anything large in or out. Once the interior is cool (& dry) opening the garage door doesn't make much difference. Bringing a hot car in usually raises the temp about 2 deg. while it's cooling down. In the evenings when the temp outside drops into the low 90's I can shut down the A/C, open the garage door & watch the traffic on the Intracoastal waterway with a drink in my hand. It takes an hour to hour & a half for the heat & humidity to become uncomfortable.

Next time I might up it to 18000 BTU, but this one has been working for almost 8 years so I'm not worrying about it.

 

[Black Oak]

I've got similar shop/climate here in Arkansas, maybe not as hot in July as you . I think a good 1 ton/ 12K unit will do fine . After I expanded to 650 sq. ft. , my mini split is great -winter and summer . Possible that humidity would factor in this , N. Calif. I'm not too sure about . Arkansas is humid and I'm happy w 12,000 btu .