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  1. #1
    Join Date
    Sep 2005

    Question Questions on Rheem/Ruud dual fuel in ATL

    We have a Rheem furnace (RGPL), a Ruud heat pump (UPPA), and a Honeywell VisionPro 8000 thermostat (not sure specifically which model). The system install was a saga that took place from Nov '05 through April '06. Somehow, the original installer found a heat pump that'd been in someone's warehouse for over a year and put it in at our place. After original GC quit, I had to bring in a 2nd company to finish the system.

    I'm trying to understand better how it's set up, mainly to see if I can adjust where the second stage is called for and avoid a service call. I was home yesterday, while the outside temp was ~40F and noticed that the gas heat was running. Having gotten what I thought was a pretty good electric bill last month, I was surprised to see the gas bill come in higher than expected. Guess that's why.

    I've looked through the VP setup some, and I believe there's also a dual fuel kit (that's what the memory register for that option says, anyway). My understanding from reading here is that the VP should be able to handle this function.

    So, here are my questions:

    1) How can I find out where the switchover between stages is set and adjust (the temp down, presumably) if necessary? I honestly don't know what the dual fuel kit looks like, but I assume it's a board mounted at the furnace.

    2) Would it make more sense to have the VP run the dual fuel setup? This is probably within my capabilities, with some guidance. At the least, it'd be nice to have an outdoor temp indicator at the VP, which isn't there now. Seems like this is a signal coming in from the heat pump that could be passed on to the VP, or would I need a separate sensor?


  2. #2
    Join Date
    Jan 2007
    You have dual fuel by virtue of the fact you have a heat pump working in conjunction with a gas furnace.

    The vision pro 8000 is designed to enable user access on a limited level. The technician set up menu is where the details are hidden on changeover, deadband, remote sensors, etc.

    You need to verify whether or not your heat pump has low ambient oeration capabililty. You also need to find out what amount of heating performance the unit will deliver as the outdoor temperature drops. Air to air units don't give off much heat when outdoor ambient temp falls below 40 deg F.

    Your system may well be operating normally. Get a qualified technician out there to check it out.

  3. #3
    Join Date
    Sep 2005
    Thanks. I've looked at the installer manual for the Vision Pro. My setup has a "1" entered in register 0210 for an external fossil fuel kit.

    I've read a lot about heat pumps being able to handle down closer to 30F than 40F. I don't have the specific perfornance data for the installed unit (unlike Carrier, Rheem/Ruud don't publish any of that online).

    If I could save some money on running the gas and still keep the place warm by lowering the cutoff temp for the heat pump, I'd like to do that. If it's something that can readily be done without a service call, that'd be great, too.

  4. #4
    Join Date
    Jun 2002
    Dacula, GA
    Try looking for an outside thermostate most likely mounted on the heat pump possibly under the cover plate for the electrical hook up. It will have an adjustment to raise it up or down. You can go up or down with the set point on the outside temp. Once the gas furnace is engaged the outside temperature will have to raise up about 2 degrees warmer to switch back to heat pump again. You will have to play with the ajustment some to get it to where you want it. Good luck.
    "I could have ended the war in a month. I could have made North Vietnam look like a mud puddle."
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  5. #5
    Join Date
    Jan 2007
    N.E. Ok.
    1 thing to keep in mind with the fossil fuel kit set point. Being gas furnace the F.F. kit will lock out H.P. below set point. If you have freezing rain overnight and H.P. is locked out ice will form on H.P. fan blades causing quiet a commotion with vibration when H.P. kicks back on.

  6. #6
    Join Date
    Dec 2006
    Middle Tennessee


    Quote Originally Posted by thull View Post
    Would it make more sense to have the VP run the dual fuel setup?

    (i) recommend having a QUALIFIED technician rewire the 8000

    to control everything, then reset parameters on the stat,

    in order to lock out your furnace to desired temp., you can also

    lock your heatpump out at desired temp, dont try it yourself

    you can damage systems and cause personal injuries!

    Last edited by Airmechanical; 01-30-2007 at 03:42 PM.

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