Heating, Air Conditioning, Fridge, HVAC/thermostat


Hi, Jim: My thermostat meter controls both heating (gas) and air conditioning (electric). Because my house was built in 1990, the old meter is hard to adjust as shown on its face, like weekday programming, weekend programming...That's OK. I can at least use its basic function---heating and air-conditioning. My question is what's the difference between "fan/auto" and "on". Under what circumstances should I use the former or the latter?
thank you in advance.

Hi Aaron,

With the stat set to "auto", the fan runs only if there is a call for heating or cooling. In the "on" position the fan runs 24/7. Normally the stat is set to auto. Some people like to run the fan all the time. This will cost you more on your electric bill. I see no advantage in running the fan all the time.

Hope this helps.

Heating, Air Conditioning, Fridge, HVAC

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Jim S.


I can answer questions on gas or electric furnaces, ac units and heat pumps. I don't work on boilers,chillers,or home appliances.


I have been in the HVAC trade for over 35 years. For the past 15 years I have owned my own business. I am semi-retired so I can answer questions in a timely manner.

I attended trade school for 5 years on weekends and evenings. This was very hard to do, but well worth it!

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