Sorry Andrew, from your first post I did not realize we were discussing SoP, only if you could test the unit below a certain temp. We are now on the second page of this thread and still waiting for someone to post limitation set by manf.
Several clients have been hvac techs, I remember one of them turning on the A/C unit (not a heat pump) in cold weather for about a minute or two. I was outside and right next to the unit when it came on, he came around the corner and said “I just wanted to see if it would run”.
See page 3
See page 3 of manual (page 4 of the PDF)
http://www.chasroberts.com/Manuals/Carrier/CR-Carrier-AC-Furnace-Final.pdf
Chuck
Thanks Chuck, I’ve seen this questions numerous times on several different m/b and this is the first time someone produced anything in writing.
Interesting tidbit…
I just replaced the thermostat for a friend. Before I began to explain to her how to use it (her old one was the old mercury type) I happend to glance at the operating instructions…
Read the Caution after section 1.3…
I don’t recall seeing this stated in the Tstat manual before.
enough said - I learned something - I had always been told not a good idea and not standard of practice but now we have manufacturer’s proof
Well **** I wrote it down!
It is in writing.
Mein Kampf was written! so what is the damn point?
Just keep following the mindless!
I attempt to explain the issue and all I get is grief because of a lack of willingness to learn something out of the ordinary.
Yeah, those home inspection schools have it all wrapped up!
see the above post.
Go ahead and do it. you’ll do it anyway.
It’s 27° here today and I ran five air-conditioners! Sue me!
Many commercial units run year round BUT they have special controls to help them do this. Like in a restaurant or building with a lot of heat load.
You hear that in cold climates many car owners have ENGINE BLOCK HEATERS or similar that keep the oil in the engine warm. Makes starting easier. A/C compressors can have similar issues.
When started up COLD the oil in the refrigerant will be sluggish and can travel through the system as such and damage the compressor or valves.
Most new units have crankcase heaters that IF energized help keep the compressor warm in cold weather. BUT how do you know its on and working. In actuality if its ON and working for the previous 24 hours, I could probably briefly start an A/C and run it down to maybe 45 degrees.
I wouldn’t get much of a heat load BUT I know it runs. HOWEVER as a home inspector doing a VISUAL home inspection, I know it came on BUT don’t know much else - Especially NOT enough to give it a GREEN light and say it works properly AND is good to go.
Therefore as a PRUDENT, intelligent and professional home inspector, when the temperature is down at 55, 50 or below / I simply state the obvious:
Every couple of years we see some idiot COWBOY home inspector think he’s being a big boy and operating the units at 40-50 degrees. Sooner or later the A/C shoots craps AND other inspectors OR HVAC service techs are more than willing to tell the owner its BECAUSE the doofus home inspector turned it on in COLD weather.
Then GUESS who gets to pay for a NEW A/C unit?
David, generally you do explain HVAC issues well, however, if you think your getting grief in this thread, it may because IMO, you haven’t explained anything…
Your previous two posts in this thread…
If you routinely run HVAC units in winter, is there anything special you do? Or do you you just set the t-stat to cool and run it?
What do you think an inspector without an extensive HVAC background should do re: AC compressors in winter?
My two cents…it depends more on the inside temp of the house being cooled than it does the outside temp. The danger is the compressor trying to pump a liquid. If the inside temp is warm enough to give the condenser some heat (superheat) there won’t be a problem. In Phoenix I start heating the house as soon as I arrive. Once I get it warmed up I feel comfortable in running the a/c.
Sorry “bad week!”
Rick, I covered this several times and I sometimes get tired of kicking a dead horse!
http://www.midtninspections.com/blog
http://www.midtninspections.com/blog?page=1
http://www.midtninspections.com/blog?page=2
http://www.midtninspections.com/blog?page=3
Does this same rule apply to the cooling mode of a heat pump. For example, if the temp is 45 degrees outside, and it has been that way for 24 hours, can I not check the AC mode of a heat pump?