Anybody in or around Texas using mini-split A/C

[Investigator]

I'm reading lots of stuff about mini-split A/C systems, really wanting to compare for my area. How well do they work for metal buildings with spray foam? I'm looking at building a 30x40x12, with 1" of closed cell foam. I'm just southeast of DFW.

 

[Boswell]

I installed a Mini Split in my 17 x 36 metal shop. I have 8" of closed cell on the ceiling and 6" on the walls. It was installed in January so I have not made it through the summer yet but so far it has been perfect. No problem maintaining temperature. I do have a large oscillating fan that keeps the air moving and adds to the comfort level but so far, no complaints. Waiting to see how it does when it is 105F outside.

 

[Investigator]

I installed a Mini Split in my 17 x 36 metal shop. I have 8" of closed cell on the ceiling and 6" on the walls. It was installed in January so I have not made it through the summer yet but so far it has been perfect. No problem maintaining temperature. I do have a large oscillating fan that keeps the air moving and adds to the comfort level but so far, no complaints. Waiting to see how it does when it is 105F outside.

8" of closed cell? Wow! Did you mean open cell? I've never heard of closed cell that thick.

 

[Boswell]

Nope closed cell. it was expensive but I believe that insulation is one of the best places to invest when it comes to climate control. My house has 12" thick , thermally broke walls with fiberglass insulation and IR barriers on the East, West and Roof. Solar Cells provide 85% of all power. I realize that it is non-conventional .

 

[Hobby_5]

Metal workshop is 24’ x 48’ but with an interior wall dead in the middle making two 24’x 24’ shop bays each with 15’ ceiling and open trusses here. Metal building with closed cell insulation I run a Mr Cool DIY mini-split in each bay.

 

[Investigator]

Nope closed cell. it was expensive but I believe that insulation is one of the best places to invest when it comes to climate control. My house has 12" thick , thermally broke walls with fiberglass insulation and IR barriers on the East, West and Roof. Solar Cells provide 85% of all power. I realize that it is non-conventional .

Metal workshop is 24’ x 48’ but with an interior wall dead in the middle making two 24’x 24’ shop bays each with 15’ ceiling and open trusses here. Metal building with closed cell insulation I run a Mr Cool DIY mini-split in each bay.

What size mini splits are you guys using? Trying to figure what is enough, what is too much, and what is way undersized for what I want.

 

[Bob Korves]

Boswell is on the correct track. It is better to keep the heat out (or in during the winter) than wasting energy over time removing (or adding) the heat. It is a matter of pay more now or pay a lot more later, not to mention the comfort issues...

 

[Stonebriar]

I don't run a min-split, but I have a 40x60x12 with 2" closed foam here in Granbury. The building doesn't get all that cold in there, down in the mid 50's, but will get plenty hot, 90's if not regulated. I have a 5 ton heat pump. And it is very easy to keep in the range I like. With short run times. When not working i keep it between 85-65. It hasn't been that expensive to run at all. The foam is WONDERFUL.

I would get at least 36000btu unit it is suppose to cover 1200 to 1500 sqft. That is usually calculated with a 8' ceiling.

 

[RJSakowski]

The required size of the A/C unit will depend on the u value of the enclosure. There are online calculators to assist.

 

[Hobby_5]

Mine are 36k BTU for 24' x 24' with 15' ceilings and 3" of closed cell on ceiling with 2" on the walls. I do have a 12'H x 16'W commercial rollup door on the west wall which is insulated as well. The mini split does a great job and my humidity levels stay around 43 - 53 percent level.