Q for the HVAC guys, HPump "exercise"

[osagebow]

We have a 2 year old trane heat pump, primarily for cooling duty. I let it run a bit in the winter, and the wife asked "why" today. I know I heard to do that on here.

What is the reason, and how often/long should it be run?

Thanks!
OB

 

[woodgeek]

News to me. Maybe to determine if it still works?

 

[begreen]

I like to exercise the components of a system regularly, be it a furnace, car, generator, etc.. One a month is what I shoot for, but for a heat pump once a season at least. We are the opposite and the AC usually only gets run once in the summer. Our house stays pretty cool in the summer and it rarely gets too hot outdoors here.

 

[Highbeam]

To circulate the lubricant and keep seals wet?

 

[heat seeker]

To circulate the lubricant and keep seals wet?

That applies to automotive units, but I don't think house units have such seals (?).

 

[semipro]

My experience with vehicles and HVAC units is that mechanical switches benefit from occasional operation. The contactors in HVAC units are electromagnetic switches (relays). There are also pressure- and temperature-operated mechanical switches. Some have been replaced with solid state switches but many mechanical ones are still used.

Edit: Same with motors that use brushes. This applies to window and blower motors and such in vehicles but I think most HVAC motors are brushless. I know most air handler and condenser fan motors are split phase (brushless) AC motors and I'm assuming that the variable speed compressors used are brushless DC.

Interesting side note: ants seem to be attracted to electromechancial switches. In Texas it was pretty common to find relays and switches malfunctioning because they were packed with ants. Maybe they are attracted to the sweet smell of the ozone created by the contact spark.

 

[semipro]

What is the reason, and how often/long should it be run?

As far as how long I always shoot for "steady state" operating where temps etc. have stabilized.

 

[moey]

Nobody turns their A/C on in the middle of winter. Let it be..

 

[heat seeker]

I have to wonder what starting the compressor with frigid oil in it does to it.

 

[semipro]

I have to wonder what starting the compressor with frigid oil in it does to it.

The compressor on a heat pump runs in the winter same as summer The freon flow just reverses.

 

[heat seeker]

Somewhere I got the idea that there is a heater in the compressor to keep the oil above a certain temperature. Is that true? I cut the power to mine in winter, since I also read that the relative warmth will attract rodents looking to keep warm. Am I reading the wrong things?

 

[woodgeek]

Somewhere I got the idea that there is a heater in the compressor to keep the oil above a certain temperature. Is that true? I cut the power to mine in winter, since I also read that the relative warmth will attract rodents looking to keep warm. Am I reading the wrong things?

Some older piston-based units had such a heater. As I understand it, modern scroll compressor units do not.