Using home AC when it's cool outside

Steve Garson_2

I just had a Trane x18i system installed win my home with cathedral ceilings. My understanding is that one should never use their AC when it is below 50 degrees outside, unless there is. Crankcase heater. My installer told me that this was not true. I question that. Surprisingly, there is no mention of this in any of the Trane documentation.

Who is correct?

Paul S_3

with the crankcase heater you would need a low ambient kit also...to keep the head pressure up and condensing temp around 95f.... the crankcase heater is there to keep refrigerant out of crankcase during long off cycles(prevent migaration) and prevent compressor liquid slugging....so will a pumpdown system.....why do you want to run a/c below that temp?

Steve Garson_2

Cathedral ceilings on sunny days heating up the second floor, even if it is 50 out. No crankcase heater

ChrisJ

Personally, I'd never use it below 60F.
You're going to get a lot of different opinions on the temperature, but likely everyone is going to tell you to never run it if it's below 50F.

Some guys say 70, some say 60, some say 55.

As had been said, a low ambient kit would solve your problems but it's more than just a crank case heater.

If I ever get the money and time to install a split unit, you can bet your butt it'll have a low ambient kit on it. It gets very damp here at night so I run the A\C instead of opening the windows. With window units I don't care, but they sure do complain a lot about the cool outside temps.

I'd never risk it with a pricey split unit.

njtommy

I would talk to your installer about adding some extra duct work and a damper to bring in fresh air from the out side. 50f air would give you free cooling.

ChrisJ

njtommy said:

I would talk to your installer about adding some extra duct work and a damper to bring in fresh air from the out side. 50f air would give you free cooling.

Except when it's damp out.
50F with 70-80% RH blows.

Steve Garson_2

Njtommy, already have it. This was more a question that surprisingly there is not in any documentation with my system, which makes me think that perhaps it is not a problem. I can't imagine Trane would go silent on the subject with the goal to sell repair parts. They would say something....wouldn't they? Maybe things are different with newer systems? But I want to know for sure.

Paul S_3

I do not install Trane...im a Carrier authorized dealer...all of there units besides there 19 SEER variable speed model need some sort of low ambient kit....they provide an accessory kit...some models go as low as -20f...some down to 0f.....I believe the minimum temp is 55f without the lo amb kit...try calling them or downloading a data sheet answer should be in there....also carriers 2 stage infinity units can operate as low as 0f...but the complete infinity system must be installed....meaning the communicating infinity control(tstat) and indoor unit with condenser....this could be similar to what you have

njtommy

@ChrisJ that's where an enthalpy control/ Honeywell jade control comes in. It adjustable control that looks at out side air and humidity to allow outside air on on dry days and will bring on the compressor when you have damp days.

njtommy

Steve where are you located. Depending on state codes you could be required to bring in some fresh air into your home. The duct size may only be say 4-8" and that would not be enough air to cool your space.

Steve Garson_2

Boston

John Mills_5

Guessing you mean XL18i? Trane says 55 as shipped. In a class last week, our tech rep said Trane really doesn't want cold weather operation on the 2 stage units. Since running in cold weather is very rare in residential, he brought up commercial where it is common. He said don't sell 2 stage residential units for commercial applications. Use a single stage. Why I don't know. Infinity systems don't mind.

njtommy

I have a feeling its just to bring some out door air temp in and that's all. It's probably not a Trane part at all.