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  1. #1

    Question Understanding a Heat Pump & Using the Fan only option on your a/c

    I have two questions:
    1) I have an all electric home and I have a heat pump heating and cooling system. I get a little confused with the options and how it all works. There is Fan or Auto for cool. What is the difference? What is the most effecient to use and when? In the winter there are two options as well; there is just Heat and there is emergency heat. What is the difference? What is the most effecient to use and when should I use the two options?

    2) My neice was told by an hvac repair person to run their fan on their a/c all the time, that it will keep the house cooler and the a/c part won't have to work as hard. One thing I noticed is her home is always hot and uncomfortable. The other thing I wondered besides if this made any sense or not is what kind of wear and tear could this be putting on her a/c unit running the fan constantly. I think it would be better to just run the a/c when it is really hot outside and that way it only has to kick in when it drops below the setting you have it at. If it is cooler outside than inside your home and you can't open your windows then I would think the fan would make some sense. But I am not sure so that is why I'm asking.

    Thanks,
    Cats

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,314
    Running with fan "on" in the summer will tend to even out the temp in all the rooms. it will also tend to increase indoor humidity, and raise the electric bill by 30 bucks a month or so. So if you want lower humidity, leave it in fan "auto".

    In winter, set the stat to "heat". Setting it to "emergency heat" will shut off the heat pump, and use only the expensive to use strip heaters.
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  3. #3
    Join Date
    May 2012
    Location
    San Diego, CA
    Posts
    352
    When the fan is "on" then it is running even if you do not have your heating or cooling on (basically re-circulating the air). When the fan is in "auto" mode then it will only turn on when you are heating or cooling the house. I would leave the fan in "auto" unless you have a fresh air damper on your system that adds a little outside air while re-circulating or if you have some other device that uses your blower fan like a dehumidifier. You use less energy when your fan isn't running continuously.

    You are right, in many commercial applications they have economizers that let in 100% outside air when it is cool outside, but they still don't have those stuff for residential so your fan is just recirculating the air in your house. Your niece might have hot and humid air leaking into her ducts for example duct leaks in the attic will bring in hot and humid attic air into the ducts and mixes with the house air.
    You can call me Sam

    It should be a crime to be a mechanical engineer in San Diego
    Summer Design Temperature: 83 F Dry Bulb ~ 69 F Wet Bulb (California Climate Zone 7)

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