Thread: Does this harm the unit?

It is 100+ degrees in Oklahoma right now and, of course, every home has the A/C running. During the HVAC inspection, is there risk to switch from Cooling to Heat to check the unit? I know you can't check the A/C if it is 65 degrees or cooler outside, but is there such a limitation on the heating unit? What steps do some of you take to switch between the two?

Sorry, I just noticed I posted in the Plumbing Forum and not the HVAC.... oops!

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Dub,

To the best of my knowledge there is no harm in switching from A/C to heat other than, the discomfort felt in the house during the operation of the heating unit. when it's 100+ deg. outside, I can't imagine the current homeowner being too thrilled about the idea of having to pay to re-cool the house after the heater has been heating up the walls & such. This is not my specific area of expertise, however it has never caused a problem for me down in the gulf south.

No matter where you are geographically located, there is no harm is cycling a thermostat from cooling, to heating, whether testing or otherwise. During a test, the heating function would be operating for less than a minute, so there is not going to be a detectable energy loss. Even if there was a detectable energy loss to recool, the testing process is required to confirm operational function.

My best knowledge is that switching from heating to cooling will have no negative effect on system. Similar to a temporary loss of power. If the AC unit was switched on and off in quick succession the compressor may shut down for 1 to 2 min then it would restart.

What type of heating system are you talking about?. Up here in PA, I don't run a heat pump in heat mode if it is 60 degrees or hotter but I will test the emergency backup mode. If it's a gas or oil-fired heating system, I'll run it regardless of temperature.

Thanks everyone for your replies. I was at an inspection this morning and I had a realtor call me down and said that her Heating and Air guy has always told her to have the A/C turned off at least an hour before turning on the heat. I had never heard this and was wondering if I was screwing up. So Nick, what are you saying, run the emergency heat mode only? How is this different from the Heat mode itself? Thanks for your help!