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  1. #1

    Continuous Fan Mode Operation

    Ran across this and as a homeowner it sounded like something to be aware of? Seems like unless your home is pretty tight and proper pressure you could be doing more harm than good running the fan even with proper media?

    "In addition, the air handler is now in constant need of an air supply. If interior doors are closed, and there are no return air paths, the air handler might satisfy that need by sucking more allergen-laden air through any gaps, holes, or orifices in the exterior shell of the house"

    http://www.advancedenergy.org/buildi..._time_off.html

  2. #2
    Thanks for the article. It does contain important information.

    In my area (North Texas) the biggest problem in running the fan on continuous mode comes from raising the humidity level. The moisture on the coil is reintroduced into the occupied space after the compressor has cycled off. This higher humidity leads to more problems with mold and dust mites.

    This also illustrates one of the problems of the "whole house air cleaners" that are attached to the HVAC system. They only operate when the system operates. On a cold winter day or a hot summer day that can be quite a bit of the time. In the spring and fall in most areas the HVAC system might run a third of the time at best - sometimes much less. Ironically, that is when allergy sufferers need the help the most.

  3. #3
    I live in the desert so humidity is never an issue.

    Seen posts about some using VS circulate setting instead but it sounds like if you don't have a sealed envelope with a clean pan,coil, and ducts you could also have problems.

    Just sealing the envelope looks to be a big & costly job.... Heard from someone who spent several plasma TV's worth ceiling his custom home envelope. (inside only)

    Another couple TV's for that special foam to enclose attic and then you need is it an ERV to get fresh air? Won't that fresh air be very hot & humid in your case or is it just a small amount/turns off when it's really hot?

    All for an energy bill that's a fraction of the cost of the above

  4. #4
    Join Date
    Mar 2007
    Location
    Birmingham, AL
    Posts
    108
    It's best not to have a bunch of interior doors closed regardless. The same applies when your HVAC system is conditioning the air. If you do not have a return in a room, it is best not to have the door closed for long periods of time.

    If humidity is not a problem, then I can only see running in the fan continuously (or in circulate mode) as an advantage in terms of indoor air quality.

    I did an Air Advice test on my home. I did 4 days with the fan in auto position and 4 in continuous on. The particulate levels evened out greatly at a much lower level when the fan was left on. There was a pretty remarkable difference.

  5. #5
    ItsHot-

    You have a FA Ductworx right? Or phi? Did you consider the variflow fan? It is nice to see "professional" members that use the Ductworx since it has been the overall chiming in that since I am not an HVAC guy I couldn't possibly know anything about IAQ and since they don't use it, it must be junk....which I know is a bunch of crap and obviously you have tried it so you know better. The excess humidity isn't even an issue with a ductworx or phi since it uses the moisture and if you have the unit then you don't have to worry about mold from the excess humidity since that humidity becomes the oxidisers...however the units don't work as good in less than 40%RH...I saw the Gaurdian air thread and just wanted to say thanks...I hate being the one of like 3 people in this section that believes in the technology.

  6. #6
    Join Date
    Mar 2007
    Location
    Birmingham, AL
    Posts
    108
    Quote Originally Posted by NHMoldInspector View Post
    ItsHot-

    You have a FA Ductworx right? Or phi? Did you consider the variflow fan? It is nice to see "professional" members that use the Ductworx since it has been the overall chiming in that since I am not an HVAC guy I couldn't possibly know anything about IAQ and since they don't use it, it must be junk....which I know is a bunch of crap and obviously you have tried it so you know better. The excess humidity isn't even an issue with a ductworx or phi since it uses the moisture and if you have the unit then you don't have to worry about mold from the excess humidity since that humidity becomes the oxidisers...however the units don't work as good in less than 40%RH...I saw the Gaurdian air thread and just wanted to say thanks...I hate being the one of like 3 people in this section that believes in the technology.
    Yes, I have the FA Ductworx and have no problems to report. I don't smell anything coming from it like I was told I might, but I did also install the variflow motor controller. It runs the blower constantly on a very low speed. I am being the guinea pig on this one. We have not installed the variflow for any customers as of this time.

    Once it gets real humid this summer, I will likely put the jumper back in so it will not run in continuous mode. I'm not worried about the moisture/mold aspect from higher humidity, but more about comfort. I'll probably run it both ways to see if I can feel a difference. But so far so good on the FA Ductworx. Customers seem to like it a lot too.

  7. #7
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    2,991
    NHMoldInspector
    " hate being the one of like 3 people in this section that believes in the technology."

    Lord its hard to be humble isn't it? LOL!
    The cure of the part should not be attempted without the cure of the whole. ~Plato

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