Problem with fan only operation
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  1. #1

    Problem with fan only operation

    I have a two story, two zone system, with a Ruud heat pump. A/C works fine, cooling and blowing when called for by t-stat settings. However, neither t-stat will operate the blower in 'fan only' mode. That is, the only way to have the fan blowing is to have either heat or a/c driving it. Both t-stats have the usual switch, labeled in the usual way (fan on/auto), but neither switch causes anything to happen.
    By the way, this house is brand-new construction. The contractor doesn't have a clue. Says it must have something to do with the fact that we have two zones, but only one heat pump unit. Doesn't understand why someone might want to operate the fan by itself.
    Anybody ever hear of this? I know I can keep raising cain with the builder, but I thought if I could point him in the right direction, it help me get this fixed.

    I guess I'm also asking if this situation could be considered 'normal' for any standard installation. It seems like my contractor and his HVAC sub just don't want to figure it out. Am I being unreasonable in insisting that they correct this?

    Thanks.

  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,207
    You have to have the thermostat wired to operate the fan only, usually a g terminal on tstat. They may not have ran enough wires for the fan circuit.

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,811
    What brand and model of zone panel? Still should have it but every panel does it differently. Is there an LED on the panel for fan only?

  4. #4
    Quote Originally Posted by BaldLoonie View Post
    What brand and model of zone panel? Still should have it but every panel does it differently. Is there an LED on the panel for fan only?
    Honeywell HZ221, and yes, it does have a Fan LED.

  5. #5
    Join Date
    Aug 2012
    Location
    North Dakota
    Posts
    512
    yes you should insist on having it done rite the fan on switch is an important feature wich I allways recomend to run fan 24-7--365 which is my opinion what this will do is a couple things circulte the air and give a more even temp. help to keep air cleaner by filtering and less starts on the blower motor thus lowering your electric bill

  6. #6
    Join Date
    May 2009
    Location
    Savannah, Ga/H.H. Island, S.C.
    Posts
    1,392
    Leaving the fan on 24/7 will create a high humidity issue. High humidity will make you uncomfortable and will create a breeding ground for mold and mildew.

    Your best option would be a thermostat with a "circulate" option (I.E. Honeywell 8000). That turns the fan on periodically and create a more even temp over the conditioned space.

    But regardless, you should be able to operate the fan in the "ON" position if you would like. I suggest calling a local AC contractor to check the wiring.

  7. #7
    Join Date
    Apr 2010
    Location
    NC Sandhills
    Posts
    379
    Not sure about honeywell zone boards but with EWC the board will always put a fan only call at least priority. IE if you have both stats set to cool and Fan On it will only open the damper to that zone and turn on blower by itself (fan only) when there is no call for cooling or heating from any zones. You can test it by turning all stats to system (off) and fan (on) and wait a few minutes. If you do not get any blowing then either it hasnt been wired, dip switched or not capable for that board.

  8. #8
    Join Date
    Aug 2012
    Location
    North Dakota
    Posts
    512
    well im not absolutely sure where this humidity is going to come from unless there is a sourse adding grains ????

  9. #9
    Thanks for all the suggestions.
    Turns out that the fan itself was wired incorrectly at the factory. It took them a while to figure that out, but they're coming today to replace the whole fan assembly.

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