Insulated Garage with A/C not cooling

[TheSourceGarage]

I just had my walls and ceiling insulated with blown in insulation this week so I can spend more time in my 3 car garage using my lift I am installing. (pics attached) I also have a 14k BTU black & decker portable ACU unit. I have a ThermoPro TP50 ambient thermometer I got off amazon for cheap I am using to check the temp and have let the AC unit run for an hour without making any change to the temperature. The garage stays at the same temp as outside. I am trying to figure out what I am missing or incorrectly assuming.

I have made sure I have no major leaks around the sides of my garage door or windows, Just a few small cracks where daylight shows through just barely that I am planning on sealing up and I will be insulating the garage door with foam board. I also have an older fridge in the garage running as our second fridge which I know is contributing a little heat.

What am I missing? Is the garage door not being insulated really letting in a ton of heat? It seems to be a thicker door and even when it is 90 and sunny out, the door itself does not get even warm inside. Is 14k BTU not close to enough for 650 sq ft? I am feeling pretty dumb right now to have had all my walls and ceiling insulated and it not make any difference in the temperature. Pics attached for an idea of what I am working with.

 

[yeldogt]

You are asking a lot of a portable unit -- they don't give full output either. Much less

Humidity is also very important -- you have to remove the water and that takes a lot of power. It's not going to happen in an hour ..

 

[LS6 Tommy]

Those portable units generally have the capacity overrated and are all very inefficient. 14k in a real unit would probably be fine.

Tommy

 

[Busted_Knuckles]

At the end of the day, its just math. What is the temp in the garage, and what is the temp at the " register " of the A/C unit, in other words is there a drop in temperature ?

Start there before going into diagnostic mode of the building. Does the A/C work ? and if it does, how many degrees if any of a drop do you get ? This will answer the question of if its actually cooling, then you can move onto where the heat load is coming from that it cant turn around.

I cooled a conventional insulated 6 car garage ( 8' lid ) with a 18k sleeve unit, on the hottest of days 90F + you could near hang beef in there ( 68ish degrees, I run a hot body temp and really like it cold ).

Not knowing what you do and dont know about cooling, it can take FOREVER for a good working 14k unit to bring the room down 15 degrees. I kept my garage cool, by never turning of the A/C, but it was insulated, including the doors, and had no windows, but was in full sun.

Food for thought..

 

[bazar01]

A 14k btu window unit will do better.

What is the discharge air temp and the cfm on your portable?

I am not going to waste my money on a portable.

 

[TheSourceGarage]

Thanks for the feedback so far. Amazon says the CFM is 206 and I have the temp set at the lowest it will go of 65. My garage is roughly 650 sq ft and it is 85 outside. What is the calculation for figuring out the time to cool or cooling rate? Trying to google this and figure it out. I swear I had an engineering degree lying around here somewhere ....

 

[PWC Repair]

Those units typically only blow half the cfm of a compareable window unit. Not to mention the heat transfer in the cabinet and through the exhaust hose. You'd be way better off with a 12-14,000 btu window unit there. In the past I was in a mobile home with a sliding window like yours. I just popped the whole window out and made a simple 2x4 frame with blocking and a piece of 3/4 advantech set flush in the frame. Then I layered in some hard styrofoam sheet. BAM! Mounted window a/c. Removed and reinstalled for a few years, worked great.

 

[Jeepster04]

Its also pulling in air from outside since its a single hose unit. I'm not sure how they would ever work since whatever air its cooling, its pulling the same amount of unconditioned air into the space.... Strange setup...

 

[LS6 Tommy]

Thanks for the feedback so far. Amazon says the CFM is 206 and I have the temp set at the lowest it will go of 65. My garage is roughly 650 sq ft and it is 85 outside. What is the calculation for figuring out the time to cool or cooling rate? Trying to google this and figure it out. I swear I had an engineering degree lying around here somewhere ....

There is no single calculation. You have to do a manual J on the building, then do the heat transfer calculations for the size unit you have and the temp/volume of air being cooled.

Tommy

 

[Mesozoic]

I'd have to agree with all the statements here, but I would say that a mini-split would probably serve your needs best in that space. A small one would suffice and it would get the job done very nicely.

 

[Black Oak]

get up to speed on mini splits , go buy one .

 

[OldSoldier]

I'd do like PWC Repair did for years. Mini splits are quite a bit more expensive than a simple wall unit, which seems like you'd be able to do since you have windows on both sides of your garage (i.e. one side probably won't face the street). I've bought two mini splits and they have not proven as reliable or hassle-free as I'd hoped. The window unit will be less efficient than a mini split but put out far better cooling than your portable unit and will probably end up being just the ticket. And only a few hundred dollars so it won't break the bank either.

 

[shade]

I'd do like PWC Repair did for years. Mini splits are quite a bit more expensive than a simple wall unit, which seems like you'd be able to do since you have windows on both sides of your garage (i.e. one side probably won't face the street). I've bought two mini splits and they have not proven as reliable or hassle-free as I'd hoped. The window unit will be less efficient than a mini split but put out far better cooling than your portable unit and will probably end up being just the ticket. And only a few hundred dollars so it won't break the bank either.

Windows units also cost a ton more to operate. they are very inefficient compared to a mini

 

[nadogail]

Where does your portable unit exhaust to? Is the exhaust temperature higher than the ambient air temperature?

 

[phansen39]

It's not going to bring the temperature down until it brings the humidity down. Is it pulling alot of water out of the air? Also running that set up only for an hour won't do much. Run it overnight.

 

[Jim greengo]

650 sq ft is a lot of area for a 1t portable ac.

 

[Bretny]

1hr run time may also not be helping. Setting the temp lower does nothing to the output of the AC until it reaches that temp. Dont forget that you also have to cool all the things in your garage for it to really get cool.

 

[Jackfre]

I'd do like PWC Repair did for years. Mini splits are quite a bit more expensive than a simple wall unit, which seems like you'd be able to do since you have windows on both sides of your garage (i.e. one side probably won't face the street). I've bought two mini splits and they have not proven as reliable or hassle-free as I'd hoped. The window unit will be less efficient than a mini split but put out far better cooling than your portable unit and will probably end up being just the ticket. And only a few hundred dollars so it won't break the bank either.

Curious, what problems have you had with your mini-splits OS? What brand?

 

[jeepxj]

have a watch:

 

[TheSourceGarage]

Thanks for the feedback everyone. I ended up installing a 15,500 btu window unit on the other side of the garage and it actually works to bring the temp down. Still slowly, but it works and if I really want to cool fast I use the window unit and the portable in tandem.