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  1. #1
    Join Date
    May 2008
    Location
    Orlando, FL
    Posts
    103

    Varitrane heat problem

    Hi
    Single duct electric heat VAV. The heat cycles on and off. The setup is identical to others that do not show the problem. Board # is x13690252-07 comm4, Voltage, flow, safteties etc all ok. Any clues?
    I verified it is setup for 3 stage electric and not pwm.

  2. #2
    Join Date
    Nov 2009
    Location
    Saskatchewan
    Posts
    493
    Can the discharge air sensor be moved? Just a dumb thought. I had an issue once with a sensor. Moved it a bit and all was well. It was almost like the hot air was not mixing right away with the cool air. Like it was flowing in a band for a bit.

  3. #3
    Join Date
    May 2008
    Location
    Orlando, FL
    Posts
    103
    There are no discharge air sensors. On any of them.

  4. #4
    Join Date
    Nov 2009
    Location
    Saskatchewan
    Posts
    493
    Huh, really? I gotta find a manuel. Maybe mine was an add on..... Are you suppose to have one? Maybe your missing a fixed resistor? Huh, our Canadian mods are most likely made different.

  5. #5
    Join Date
    Mar 2010
    Location
    Va.
    Posts
    180
    Are you sure it's not cycling on the high limit?

  6. #6
    Join Date
    May 2008
    Location
    Orlando, FL
    Posts
    103

    yes I am sure

    Yes I am sure it is not cycling on high limit. The power/signal stops at the board itself. There are no fixed resistors either. I thought of that. Worked before. Dont now. I go back when I have a clue. Or a new board to try. Hate doing that really.

  7. #7
    Join Date
    Nov 2006
    Posts
    13
    is the min heat cfm being meet ?

  8. #8
    Join Date
    Jan 2011
    Location
    Long Island, N.Y.
    Posts
    14
    Is the vav in heat or cool mode ? is it on a Bas like summit. In summit there is a min. heat cfm set point that has to be set high enough to keep the limit from tripping.

  9. #9
    Join Date
    Oct 2010
    Location
    Memphis Tn
    Posts
    33
    If the safeties are all made and the unit is making it's min heating cfm then it is more than likely the board. If you don't want to be a "parts changer" try swapping it with a board that you know works. My guess is the board. Good luck.

  10. #10
    Join Date
    Jul 2001
    Location
    maryland
    Posts
    1,355
    Where are you measuring voltage when you say the signal/power stops at the board? There should always be 24v present at the contactor(s) if the safties are made.
    Saving the world...one service call at a time.

  11. #11
    Join Date
    May 2008
    Location
    Orlando, FL
    Posts
    103

    Thanks

    Hi guys
    Sorry for the delayed response. The minimum cfm idea is not it since I tried using a higher minimum and it did not work. It is on a summit BCU. I dont recall the terminal numbers but there is one slightly offset to the right that I will call common to the heat contactor. And then three more terminals for the three stages. When between the common and stage 1 or two becomes live the contactor/s pulls in. When I read 0 vac the contactor drops out. That is what I meant earlier by at the board. So I guess I am at the change the board stage.

  12. #12
    Join Date
    May 2008
    Location
    Orlando, FL
    Posts
    103

    whoops

    Quote Originally Posted by Trane Guy LI View Post
    Is the vav in heat or cool mode ? is it on a Bas like summit. In summit there is a min. heat cfm set point that has to be set high enough to keep the limit from tripping.
    Heat mode, Room temp 67, Summit BCU.

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