how much do door air gaps affect A/C

[mikeyr]

I have a mini-split in my shop, shop was built with 2x6 walls (R19 or R21 forget which) so I could put in more insulation and attic has R49 so I am super well insulated in So. Calif. Shop stays cool on 90-100 degree days until late morning or noon without A/C on, by cool I mean high 70~80ish by noon much cooler than outside implying to me good insulation. BUT I have 9ftx9ft barn door on the side with gaps of 1/4" to 1/2" all around that I could pretty easily close off with a some door seal if it would help, my question is really the garage door. About 1" gap on side and at the top, can i really be losing that much AC out that door to make a difference ? I notice my A/C wont keep up with 100 degree days and my shop will get into high 70s, yet the A/C guy that installed it says i am properly sized at 24k for 980sq. ft. The garage door is a flip up solid metal door with insulation but unfortunately it is facing West so gets full sun in the afternoon. Shop does have 9ft walls so that adds some square footage I guess, A/C blows super cold and has been checked by a second A/C guy who also said it was proper size. Do those air gaps really make that big a difference ? and how do I seal garage door ?

 

[u3b3rg33k]

call it a 1" gap around a 9' square? napkin math says that's a 432sq in opening? sounds like you've got a large window open and are wondering why you can't AC the outdoors.

throw in a second 24k mini and you should be GTG.

 

[The Cobbler]

I remember years back , someone said, having a 1/16" gap all around your door doesn't mean much, but no one would think a hole in the door 6"x8" would be a smart idea .
figure out the math

 

[dcg9381]

throw in a second 24k mini and you should be GTG.

Or he could add some door seals before throwing money at a 2nd AC. If I had a 1/4-1/2" gaps in the door, I'd want to seal that up to keep out the bugs anyway.... Bound to attract them at night if the lights are on and the door is closed.

 

[u3b3rg33k]

Or he could add some door seals before throwing money at a 2nd AC. If I had a 1/4-1/2" gaps in the door, I'd want to seal that up to keep out the bugs anyway.... Bound to attract them at night if the lights are on and the door is closed.

it was a joke/sarcasm, meant to be illustrated by the ridiculousness of the task. DOUBLING your AC capacity is a ridiculous suggestion. unfortunately, heating systems are often 2-3x the size they need to be, so maybe it didn't come across.

 

[dcg9381]

it was a joke/sarcasm, meant to be illustrated by the ridiculousness of the task. DOUBLING your AC capacity is a ridiculous suggestion. unfortunately, heating systems are often 2-3x the size they need to be, so maybe it didn't come across.

Sorry, I missed the sarcasm, but I certainly get it when you might want 2x HVAC capacity for quick cool down - accomplished by multiple ductless systems.

I run 2 x 24K for 2400 sqft. I have 3 x 12x14' doors (uninsulated/roll up) and added seals. I use spray foam, but it's probably R15 at best... The shop will cool down when it's 100 outside, but our south wall is shaded...

 

[fitter30]

Humidity and mass are the hard things to cool. Dropping air temp is the easy part. Humidity is like temperature high flows to low. Have couple thousand lbs of tools or metal. Garage closed up for a day or two gets 10-20° warmer. 10°= 20k btu's plus the gap around the door.

 

[mikeyr]

OK, ok, I am going to try some door seals. I had not done it because I really didnt think it was that big a deal and didnt think it would make a big difference. Door seals for garage door and weatherstripping for other door.

 

[u3b3rg33k]

Sorry, I missed the sarcasm, but I certainly get it when you might want 2x HVAC capacity for quick cool down - accomplished by multiple ductless systems.

I run 2 x 24K for 2400 sqft. I have 3 x 12x14' doors (uninsulated/roll up) and added seals. I use spray foam, but it's probably R15 at best... The shop will cool down when it's 100 outside, but our south wall is shaded...

no worries. if I had a big garage and was doing a minisplit, I'd consider a 5 ton single head at the right price over a "right sized" 2 ton, ONLY because it'll modulate down to the "right size" once it's near setpoint, which isn't how conventional systems work. otherwise. not a chance.

OK, ok, I am going to try some door seals. I had not done it because I really didnt think it was that big a deal and didnt think it would make a big difference. Door seals for garage door and weatherstripping for other door.

let us know how it goes!

 

[scooterbum46]

I used a couple of rolls of "bent L" M-D garage door bottom seal on the door jambs adjusted so there was a slight seal, not so tight as to interfere with the opener. Works great for my heated shop.

 

[FL Guy]

I used a couple of rolls of "bent L" M-D garage door bottom seal on the door jambs adjusted so there was a slight seal, not so tight as to interfere with the opener. Works great for my heated shop.

Pics?

 

[scooterbum46]

Pics?

I will ...

 

[scooterbum46]

Sorry for delay, the one with my hand shows the profile. The other two are views from inside the door looking at the jamb and outside. Ihad the door closed and just nailed it on the jamb so it was tight to the door, but not so tight that it was pressing really hard. Probably need more pics..

 

[scooterbum46]

Sorry for delay, the one with my hand shows the profile. The other two are views from inside the door looking at the jamb and outside. Ihad the door closed and just nailed it on the jamb so it was tight to the door, but not so tight that it was pressing really hard. Probably need more pics..

 

[mikeyr]

I am looking for something for the garage door but I have a solid flip up door, I could not do a roll up due to my lift getting in the way. Home Depot has a brush like thing which will help but was looking for something solid to provide a better seal.