Garage improvements to help a portable ac unit.

[schnutzy]

Alright y'all, I have a 350sqft detached garage, the walls are insulated, the ceiling is just drywall with no insulation above it. The 9 foot wide door is insulated with foam panels, but south facing and it still gets mighty warm around the door throughout the day.

In about a week we will be starting a lot of interior renovations on the house and the goal was to set the garage up as a place for the dogs to hang out while the contractor and his crew is working. Gets the dogs out of the way, and they won't be getting all jumpy from the loud noise.

I've got a portable ac unit in the garage right now, but it's struggling. It's sized appropriately for the square footage, but I think between the bay door and the lack of insulation in the ceiling is a bit much. Ideally jumping to a bigger unit would be the goal, but none of the local places have them in stock, and we don't know if ordering one would get there in time.

I'm looking for ideas that might help things out that won't break the bank cause the kitchen cabinets are already doing a good job of that. I was thinking insulating the exhaust hose for the unit, thermal curtains for the east facing window(the only window) and something around the garage door. Maybe a roll of the reflective radiant barrier insulation stuff on the inside of the bay door? I'm looking for ideas, tips, tricks, whatever y'all have. As of now, the unit can generally keep things to a very dry 80 degrees in the garage when it's humid and 90 outside. With forecasts putting temps much closer to 100, I'm looking for any advantage I can get to keep the dogs calm and comfortable.

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[nadogail]

More insulation is better, add cellulose or sawdust above the ceiling.

 

[gc427]

Insulate ceiling heavily and add a second portable air unit

 

[Bert_]

Get a real air conditioner or a window unit. The portables are not good. They don't cool as well and use more energy.

 

[Rusty Fords]

Ceiling Insulation even bats are better then nothing.Most all of your heat is most likely pushing down through the ceiling yes even with the south facing doors.

 

[cvairwerks]

Stick a piece of blue or pink foam sheet in the window and run a decent fan oriented to help push warm air off the ceiling. Fan direction should be to help boost the a/c flow.

 

[Jking24]

I agree with the window unit. Those portables are about worthless they blow cold air that's about it they will not condition a space. I have a 400sqft garage with high ceiling in Maryland not quitea hot but high humidity. has r13 in the walls and ceiling. I cool it with a small window unit. Can't ten remember the size but generally your gonna be limited by your window opening anyway.

 

[CoogarXR]

A friend gave us an 8000btu portable. We tried it in our bedroom because it was quieter than our window unit. It doesn't even do as good of a job as our little 5000btu window unit.

 

[schnutzy]

Thanks for the responses y'all.

I've got an oscillating wall mounted fan just above the unit too help move the cool air coming out around.

The window is a side opener, so a normal window ac unit isn't an option unfortunately.

Ceiling insulation is on the list, it's just on the list to happen the same time as the house, after all the interior work is done.

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[Deude_Mann]

+1 on the window unit...

The deal is, unless it is a dual-air-hose portable unit (most are not), it will not cool well. Air is pulled from the space and blown outside to cool off the condenser coil. That means hot air from outside has to be drawn into the inside to maintain that flow. That's inefficient.

A window unit keeps all of the condenser (hot) airflow outside, and all of the evaporator (cold) airflow inside so it is inherently a lot more efficient. Since your installation is temporary it is probably not worth installing a mini-split unless you plan to use it long-term.

I have put my money where my mouth is. I just bought a big window unit to cool off a shop I am currently finishing the interior on. Eventually it will get a mini-split and I will sell the window unit.

 

[Milton Shaw]

The portables I have seen are made for spot cooling, that means blowing on someone working not trying to cool the whole shop. Get a window unit and remove the side window and block the rest of the window with plywood with a piece of foam over it for the summer construction season. A reflective curtain outside the garage door would keep it from getting so hot but nothing is going to work if you keep that portable unit. You could just build a indoor dog house and run the portable directly into it to keep the dogs cool.

 

[gfmucci]

A friend gave us an 8000btu portable. We tried it in our bedroom because it was quieter than our window unit. It doesn't even do as good of a job as our little 5000btu window unit.

I have a 14,000 btu portable unit in my 417 sq. ft. attached garage, surrounded by indoor space on three sides with insulated ceiling and insulated garage door facing south - the hot side. No windows; the AC is vented out the soffit.

I learned there are two methods to measure btu's. The original method is ok for built in units, mini-splits and window units.

The newer method I believe was designed to address the performance limitations of portable units.

While my portable unit is rated 14,000 btu's the "old" way, the new btu rating method has it around 8,000 btu.

That being said, it reduces my garage temp 10 degrees from outside temp. 95 degrees outside - 85 inside.

If I set its timer to start it in the morning a couple hours before its needed, I can maintain high 70's most of the day. It is a single hose unit.

I also installed a closable vent in the garage door and a powered vent, with damper, in the ceiling blowing through the attic and out through ridge vents. Both of these allow greater flexibility for cooling and air circulation. I have a remote thermometer in the attic which often reads over 120 on hot days.

What would be even a challenge for an 18,000 btu mini split is when you drive a vehicle with a hot engine block and exhaust system into the garage. It'll raise the garage temp a good 10+ degrees for the next couple hours.

 

[dcg9381]

Alright y'all, I have a 350sqft detached garage, the walls are insulated, the ceiling is just drywall with no insulation above it. The 9 foot wide door is insulated with foam panels, but south facing and it still gets mighty warm around the door throughout the day.

Most heat gain/loss here is out of the roof. I'd start with bats above the ceiling drywall or blow it in (you can DIY from home depot).

Have seals on the doors?