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  1. #1
    Join Date
    Sep 2006
    Posts
    136

    On, auto or CIRC on IAQ fan settings

    I apologize in advance. I'm sure this has been answered before, but this forum will not allow searches on 2 or 3 letter words.

    I'm having a 2 stage AS HP and 2 stage VS furnace installed next week. I'm also getting a IAQ installed.

    In looking at the settings for the fan, and it can be set to AUTO, ON or CIRC. With a VS furnace, I'm sure that the AUTO setting is the least valuable. But I'm wondering about the Pros and Cons of using ON vs. CIRC.

    Any sage advice? And Twilli, don't say Coleman!
    Thanks,

    Mark

  2. #2
    Join Date
    Nov 2000
    Posts
    1,251

    Try the "ON" setting.

    That furnace (if it is set up right) has a nice feature that slows the blower down to 1/2 of the A/C's cfm setting when there isn't a call from the thermostat for heating or cooling. This gives you constant air circulation, filtration, and even will allow for humidification if you have one, all while using only 60 to 80 watts of power.
    The "CIRC" setting just runs the blower enough to meet some of the minimum ventilation rates called for in some building codes. The best place to read up on it is on Honeywell's web site.
    "You do not merely want to be considered just the best of the best. You want to be considered the only ones who do what you do.".... Jerry Garcia
    "You just have to decide if you're a Tigger or an Eeyore,..I think you know where I stand on the great Tigger/Eeyore debate." Prof. Randy Pausch

  3. #3
    Join Date
    Sep 2006
    Posts
    136
    Thanks!
    Thanks,

    Mark

  4. #4
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    Quote Originally Posted by markf57 View Post
    I apologize in advance. I'm sure this has been answered before, but this forum will not allow searches on 2 or 3 letter words.

    I'm having a 2 stage AS HP and 2 stage VS furnace installed next week. I'm also getting a IAQ installed.

    In looking at the settings for the fan, and it can be set to AUTO, ON or CIRC. With a VS furnace, I'm sure that the AUTO setting is the least valuable. But I'm wondering about the Pros and Cons of using ON vs. CIRC.

    Any sage advice? And Twilli, don't say Coleman!
    I am a homeowner in S.Texas where humidity control is one of our most important concerns. FWIW I also have 2-stage A-S equipment with their VS furnace. Are you in a climate dominated by heating or cooling? There is a shortcoming I believe in the design of the CIRC feature as it applies to humid areas.

    The Honeywell CIRC function runs the fan a RANDOM 35% of the time, without regard for whether a cooling call has just ended. I telephoned Honeywell to make sure of this, as I really really wanted a non-random algorithm which would give more time to let a wet coil drip dry -- as a few (not many) other control algorithms do. The result is using CIRC raises humidity unnecessarily, just only 35% as much as running the fan full time.

    It would be so easy for them to implement using a counter algorithm, count a certain number of minutes fan-off, then a certain number fan-on. There would be no lesser performance for the existing design goal to have 35% fan runtime, just it would be not random. But as near as I can tell those guys up near Canada cannot even focus on what we need in the hot-humid South. My phone call to Honeywell's technical people ended with them telling me I should consult my HVAC contractor, which to my ears sounds the same as go suck an egg. No wonder we say "damn Yankees" from time to time!

    If it weren't for this I would own two of those Honeywell beauties. Everything else about them looks absolutely first class.

    Hope this helps -- Pstu

  5. #5
    Join Date
    Sep 2006
    Posts
    136
    Pstu:

    Thanks for your insight.

    I'm in Colorado where the climate is dominated by heating and humidity is rarely the problem.
    Thanks,

    Mark

  6. #6
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,062
    Run the fan in the on position 24/7. Where in Colorado?

  7. #7
    Join Date
    Sep 2006
    Posts
    136
    Quote Originally Posted by second opinion View Post
    Run the fan in the on position 24/7. Where in Colorado?
    Longmont. Are you close?
    Thanks,

    Mark

  8. #8
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,062
    Quote Originally Posted by markf57 View Post
    Longmont. Are you close?
    I am on the east coast now but grew up there and If I live long enough I plan on mooving back.

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