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  1. #1
    Join Date
    Dec 2004
    Posts
    61

    Hmm

    Furnace is an American Standard AUY060 variable speed two stage. (Same as Trane TUY060)

    So I was looking in my furnace while changing the filter the other day and I notice how my humidifier is wired. They put a transformer outside the junction box which is just underneath the front of the combustion chamber area. (Temperature sensitive?) A 24 volt lead goes from the transformer to the main furnace board "R" terminal, and another lead goes from the "W1" terminal to the humidifier. In other words, it is connected in parallel to the thermostat!

    Now this works, but why did they do it this way? The main board has a power connection specifically for a humidifier. (I think it is 120 volts, so it would be wired to turn the whole transformer on and off, no wiring to the thermostat terminals).

    Frankly I'm surprised this didn't cause electrical problems to the furnace since the humidifier transformer and the furnace board both get their 120 v from the same source. Seems like a hack job to me.

    The humidifier is the basic American Standard (Aprilaire) bypass job with a drain and solenoid to control water flow on/off.

    Is there any problem with this transformer in this location or the wiring method? (I didn't find it either in the furnace or humidifier install directions). At the least it keeps that 15 watts burning all year instead of just when the thermostat is calling for heat

  2. #2
    Join Date
    May 2006
    Location
    Las Vegas,Nevada
    Posts
    339
    I haven't read up on the specs but do you think,maybe,just maybe,the humidifier is wired to only come on during a heat call? W1 is the heat side of the T-Stat.Some units are not set up the same as others so modifications must be made.

  3. #3
    Join Date
    Dec 2004
    Posts
    61
    Originally posted by smngmu
    I haven't read up on the specs but do you think,maybe,just maybe,the humidifier is wired to only come on during a heat call? W1 is the heat side of the T-Stat.Some units are not set up the same as others so modifications must be made.
    Well that is true, wiring the humidifier in parallel to the first stage heating (i.e. to R and W1) means that the humdifiier only comes on when the thermostat is calling for heat. (That is another issue and kind of defeats the point of plumbing the humidifier to the hot water heater, which is a lot less efficient than the furnace).

    I guess they used the hot lead from the transformer so it doesn't cause something to get zapped when it touches the furnace board, but it still seems like a poor practcice to me.

    I just didn't think that the furnace board's R terminal would be expecting an external voltage to be applied to it from a third party transformer.


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