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  1. #1
    Join Date
    Feb 2008
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    78

    Trane Dual Fuel Wiring question (not DIY)

    I have a trane XL14c Dual Fuel unit with 3 stage heat (heat pump, low fire gas, high fire gas). It is wired to a Honeywell HZ432 zone panel (2 zones). I notice that the W1 wire is connected from the unit to the panel, but there is no connection at W2. Shouldn't W2 be connected to enable the 3rd stage of heat (high fire gas)?

    I also noticed that the wiring from the thermostat EIM (VisionPro IAQ) to the zone panel also has only W1 but no W2 wire. So it appears to me that the thermostat, which is capable of controlling 3 stages of heat, will not be able to control stage 3 heat, correct?

    The manual for the Trane unit says that if there is a jumper frrom W1 to W2 on the unit, then stage 2 heat will run for 10 minutes and then kick up to stage 3 heat automatically. I checked on the unit, and there is no jumper. So it appears that neither the unit nor the tstats are wires to enable stage 3 heat. Am I correct?

    Also, in the unit, I notice that the W1 and the W3 wires are both connected to the W1 wire that run to the zone panel. In other words, the W1 wire connected to the panel from the unit is actually the W1 and W3 spliced together. Why would that be? What does W3 do?

    My goal is to

    a) Ensure that SOMETHING will enable and control 3rd stage heat, and
    b) Preferrably wire things so that the tstat and not the unit controls the heat stages.

    Any help is appreciated.

  2. #2
    Join Date
    Feb 2008
    Posts
    78
    Anyone willing to help me out? I'm meeting with the tech on Monday, so hopefully he'll know, but he didn't inspire much confidence the last time he was here (tried to say everything was working properly until I basically insisted he test things, and lo and behold I have a defective damper which he's replacing Monday). Yes, I know - get a new tech, and perhaps I'll do that. But if I know what needs to be done, all I need is for him to do it. So any advice you guys can offer could save me a bunch of time and would be greatly appreciated.

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,765
    The zone panel can only control 2 stages of gas back up heat.

    From your description, your system is miswired as you suspect.
    Have the tech read the instructions for wiring, and its an easy fix.

    It sounds like this is the first time they installed this type of zoning and system.
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  4. #4
    Join Date
    Feb 2008
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    78
    Quote Originally Posted by beenthere View Post
    The zone panel can only control 2 stages of gas back up heat.

    From your description, your system is miswired as you suspect.
    Have the tech read the instructions for wiring, and its an easy fix.

    It sounds like this is the first time they installed this type of zoning and system.
    Just for clarity, the three stages I refer to are:

    Stage 1: heat pump
    Stage 2: low fire gas (stage 1 gas)
    Stage 3: high-fire gas (stage 2 gas)

    As I understand it, the corresponding terminals on the furnace for these stages are:

    Stage 1: Y
    Stage 2: W1
    Stage 3: W2

    So, if there is no W2 wire going from zone panel to furnace, then 3rd stage heat (2nd stage gas) will not work. Correct?

    Any opinion on why W3 and W1 are spliced together in the unit as mentioned? The Service Facts (page 9) actually shows the W3 as high blower speed and W1 as low on the unit. W2 is not marked as wired to anything. That's the extent of my ability to decipher the diagram, so if someone wants to take a look at it and let me know what they think, I'd be eternally grateful.

    Mainly I just want to know:

    1. Should there be a W2 wire from the furnace to the zone panel to enable 3rd stage heat?
    2. Why is the W3 and W1 wire from furnace spliced together and connected to the W1 on the zone panel? What is W3 doing in this situation?

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,765
    Sorry, I was thinking 2 stage heat pump, and 2 stage gas furnace.

    He probably has the second stage controled by the timer on the furnace control board.

    Since its zoned, you want it controled by the zone panel.

    The truezone system is relatively new. So your tech probably isn't too familar with it.

    Show him what the install instructions say. If he can't wire it right after that. You'll need your contractor to send out a tech with more experience in control wiring.
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  6. #6
    Join Date
    Dec 2006
    Location
    Middle Tennessee
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    *

    are you sure there is a W3 on the furnace, or is that on the zone controller?

    something don't sound right!



    .

  7. #7
    Join Date
    Feb 2008
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    78
    Quote Originally Posted by Airmechanical View Post
    are you sure there is a W3 on the furnace, or is that on the zone controller?

    something don't sound right!



    .

    100% sure - I took off the access panel and looked (didn't touch!). There are W1, W2, W3 terminals on the ECM Fan Control board. There is a white wire in both the W1 and W3, nothing in the W2. The W1 and W3 wires are spliced together to the white wire that goes to the W1 terminal on the zone panel.

  8. #8
    Join Date
    Dec 2006
    Location
    Middle Tennessee
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    if it does have a W3 i am curious what's the model# for the furnace?

    here is a layout a of Trane's the standard variable speed furnace

    http://i148.photobucket.com/albums/s...mfortrback.jpg



    .

  9. #9
    Join Date
    Feb 2008
    Posts
    78
    Quote Originally Posted by Airmechanical View Post
    if it does have a W3 i am curious what's the model# for the furnace?

    here is a layout a of Trane's the standard variable speed furnace

    http://i148.photobucket.com/albums/s...mfortrback.jpg



    .
    I'll try to get a photo today or tomorrow. I don't have a pdf of the Service Facts, but it shows it right in there. If you have access to the Service Facts for the XL14c (4DCY) take a look at it.


    I have that image you posted, but don't know exactly what I'm looking at. Is that schematic an actual diagram of what it looks like, or just a represenation of the connections?

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