Inspecting HVAC this winter

Hi Guys,

I would like to get some feedback on best practices for inspecting the HVAC systems this winter…you’re never to smart to learn something new.
(and I believe this will be of benefit to the beginners out there.)

thanks to all.

Ted it would never get cold enough to cause an issue where you are. Plus most are going to be heat pumps so temp is irrelevent. If its running in heat, its running in cold, with the exception of a reversing valve.

Here once it get cold and stays cold I will not run A/C’s

Thanks for the reply…however it does get cold here and there are times that we should not test the A/C (rule of thumb for me is below 60)…I’m just looking for imput from other inspectors as to their opinion of what to do or not to do.

I think it would be nice to have some back and forth “tips/training” instead of the finger pointing between the usual suspects.

Ever see a soda machine installed outside? if yes was it affected by the cold

Ted is right,

In some areas some times it does get very cold. Once it drops in the low 60’s I won’t turn the cooling on only the heat.

Come on Wayne, you know good and well that all system designs are not the same. Some are designed to operate in low ambient conditions and some are not.

Some equipment is designed for low ambient operation and have the appropriate components (such as a fan cycling control or a head pressure controller).

There are not too many Coke machines out there that have a furnace attached to them that drives the refrigerant from the evaporator coil to the exterior condensing unit and compressor where it will condense into the refrigerant oil of the compressor throughout the winter months. You go turn it on and the compressor which is not designed to pump non-condensable refrigerant oil blows a gasket!

Do not check older Heat Pumps in the Cool mode when the temperature is under 60 F. You may damage the compressor. Newer units should not present a problem for testing. You can check the manufacturers operating instructions online but I don’t check cooling in that temp range when the unit is older than the year 2000. That might be a little high on the date but I don’r want to buy a new compressor.

Now who is goiing to figure this out on the inspection site?

What is an "Older " unit? One with a recip compressor? Who knows the difference when they are not certified and qualified in the first place?

Lennox had scroll compressors in the 80’s, some still don’t have them…

Please tell me why an older “Heat Pump” can not run in the cooling mode when they do it every 45 min. under normal operation? We are talking about A/C units. Most are not designed to run in the cold, but a Heat Pump is.

Certainly nothing to be general or ambiguous about


I am curious about your reasoning. The condensing unit on a heat pump runs the same whether it is set for heating or cooling. It only changes the position of the reversing valve. Therefor, the compressor is running the same either way. Also, as was mentioned above, it goes into cooling mode periodcally to remove any frost from the coils.

Seems like were beating the dead horse here.

How many straight a/c and furnaces do you guys in FL come across a year. I bet it would be 1 in every 100 if not more.

You might be surprised by how many gas furnaces I see.

Yup, lots of gas furnaces…

Florida is right next to the gas & oil fields!

It doesn’t really get cold though, they just think it is! :wink:

Actually you it feels, cooler/hotter because of the humidity.

The problem with running an A/C in the winter is not as much about the cold as it is that the furnace drives the refrigerant to the compressor oil outdoors.

Doesn’t really matter how cold it is, the result (oil slugging) still happens when the furnace has been operated previously.

It’s like a still.
Hot goes to cold and condenses in the oil.

One cannot convince someone against their will as they will be of the same opinion still. :shock:

The reasoning makes no sense so why bother

Great question and above my pay grade. As a G.C. many P.E.'s (mechanical) reconmended unless your a qualify contractor (HVAR) not to operate the unit in “Cool” mode in cold temps. as it has something to do with the sensing bulbs singaling the unit how to operate. Not being a HVAC or HVAR contractor I do not run units in “cool” below 60F. or “heat” above 65F. If someone on here wants to explain the technical operation I always like to learn more. I don’t take chances damageing older equipment at MY expense. As I don’t walk on every roof-John Wayne is dead!
Thanks for the information.

Thanks to those who responded to my post…if anyone is interested I have a full page disclaimer I include in my report when I do not test the A/C during this season. Email me and I will send it to you.

99.99% are straight ac condensers with electric heat strips in air handler. I have only seen one working gas furnace in many of 1000’s of Florida inspections. Being from New Jersey I knew what I was looking at. My question was where is the owner from, and it turned out Michigan. I have seen many gas and oil none working ones installed in the early 70’s. Forced hot air but window A/C, go figure.

My experience with these are about 95% heat pumps and 5% straight cool w/ heat strip. Most heat pumps have the emergency heat strip in my area, which I always check in any season. Heat pumps are much more prevalent in the milder climates. North Florida may see more gas furnaces or straight cool w/ heat strip, but mid to south FL uses heat pumps.

I am also hesitant to test the cooling cycle on a heat pump below 60 degrees. I really don’t know if this is going to cause damage running this for a few minutes. Maybe someone has some kind of a flow chart (go or no go) for this kind of functional testing of heat pumps in the summer or winter.