Thread: Portable AC creating too much negative pressure. HELP

I have a single hose portable AC inside my medical grow room built inside my garage. The problem is its creating too much negative pressure and due to the garage being so hot the air it is bringing in is causing the room not to cool well. Should I move the AC outside the room and duct the cool air in or something else? Please help.

The AC is also the only air exchange happening in the room currently. Other then that its pretty well sealed.

Room is 10x10 AC is oversized (13k BTU if I remember currectly). Temp is having trouble dropping below 83 degrees, room is for veg only

The exhaust from the unit should be vented outside. Like on the instructions of the a/c unit. pr

Originally Posted by painretreat

The exhaust from the unit should be vented outside. Like on the instructions of the a/c unit. pr

The 100 degree exhaust going into my 115 degree garage isnt whats causing the issue. The room pulling in 115 degree air from my garage is. Thankyou though.

i run a portable a/c....the heat will accumulate(increase)...you have to power vent(an additional draw fan is required because the a/c cannot PUSH enough air to cool itself... it if it stayes inside...these little units MUST be able to cool themselves to operate properly

Originally Posted by azdesertdweller

i run a portable a/c....the heat will accumulate(increase)...you have to power vent(an additional draw fan is required because the a/c cannot PUSH enough air to cool itself... it if it stayes inside...these little units MUST be able to cool themselves to operate properly

I moved it to the outside of the room into the garage ducting the cold air in. Its creating positive pressure but I put in a backdraft flange to alleviate that. Now it seems like the AC keeps going cold to hot cold to hot. :/

this is the bane of my existance...fuggin HEAT...you say you're in the garage?does it have vents up top?......i've experimented with (sealing the rear of the a/c unit and power venting it out,unless you have a major drawing inline fan...it makes the unit heat up...no good...you have to vent the garage,find a way to stick the front of the unit inside the growing chamber,leave the rear outside...if you can, power vent the garage....its trial and tribulation my friend...

Originally Posted by azdesertdweller

this is the bane of my existance...fuggin HEAT...you say you're in the garage?does it have vents up top?......i've experimented with (sealing the rear of the a/c unit and power venting it out,unless you have a major drawing inline fan...it makes the unit heat up...no good...you have to vent the garage,find a way to stick the front of the unit inside the growing chamber,leave the rear outside...if you can, power vent the garage....its trial and tribulation my friend...

I moved it to the outside of the grow room having it pump cold air in and that seems to work for now. My new problem though is it keeps throwing the breaker after 45 minutes or so worth of use. Theres a fluorescent light and 2 small fish tanks hooked up to the same 20 amp breaker and the AC uses 11 amps so I should be fine by a wide margin of error. Any thoughts?

run the a/c on a seperate line....(breaker).......I don't think thats the fix tho....its throwing the breaker because the a/c unit is too hot....you HAVE to vent the garage

Originally Posted by azdesertdweller

run the a/c on a seperate line....(breaker).......I don't think thats the fix tho....its throwing the breaker because the a/c unit is too hot....you HAVE to vent the garage

The garage is far detached from the house so the only thing I really have to vent it with some days is 115 degree weather. Any suggestions?

Originally Posted by ShibaSpeak

The garage is far detached from the house so the only thing I really have to vent it with some days is 115 degree weather. Any suggestions?

to properly cool that space you will need a 3 to 5 ton unit. your current unit is not able to keep the demand in an easy limit. that is why is it going hot to cold on you.
if you are hydroponic chill the water. 115 is hard to deal with indoors. you will need 3-4 times the normal ac to keep up and not have problems.

Originally Posted by Bloomin Idiot

to properly cool that space you will need a 3 to 5 ton unit. your current unit is not able to keep the demand in an easy limit. that is why is it going hot to cold on you.
if you are hydroponic chill the water. 115 is hard to deal with indoors. you will need 3-4 times the normal ac to keep up and not have problems.

I only need to cool a well insulated ~10x12 room inside the garage not the entire garage itself. Worst case scenario from what Im told they have dual hose AC units that will cool the room with no air exchange and work fine but Id like to avoid that expense if I can.

I apologize if I didnt make that clear my AC is ~12000BTU and I have a room inside the garage thats well insulated and ~120 square feet and 8 feet high.

heh ok, I read your space size.( originally 10x10) if you seal the lights and run a 24/7 vent system on them possibly, otherwise 3 ton. with a 3 ton unit you will be able to have it cycle instead of draw power 24/7. i would say on a 10x 10 you have at least 5k watts of heat to deal with @ about 25 deg+/- added constant heat, you will need to chill the air to the upper 50s fast to run a sealed room at 80 deg +/- and get it to cycle....better get one hell of a dehumidifier too...doh more heat...

Originally Posted by Bloomin Idiot

heh ok, I read your space size.( originally 10x10) if you seal the lights and run a 24/7 vent system on them possibly, otherwise 3 ton. with a 3 ton unit you will be able to have it cycle instead of draw power 24/7. i would say on a 10x 10 you have at least 5k watts of heat to deal with @ about 25 deg+/- added constant heat, you will need to chill the air to the upper 50s fast to run a sealed room at 80 deg +/- and get it to cycle....better get one hell of a dehumidifier too...doh more heat...

This is a veg only area so 4x400 watts plus I had room for the AC and room to work. The ducting draws from the garage and vents to the garage so the only air flow in or out of the room is going to be AC.

AC was running on outlet with a big fluorescent... forgot they actually pull more wattage then a similar T5. Trying test run number 7 or so.