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  1. #1
    Join Date
    Jun 2009
    Location
    Northwest IN/Chicago
    Posts
    268

    Waiting For Equipment

    Got a Prestige IAQ in my house. set up for 2 heat/1 cool. Have tried almost every combination possible in the installer set up but whenever I turn the heat up enough to kick in second stage it'll always kick back down to low fire a couple degrees shy of setpoint (like it's supposed to) But then it kicks the furnace off and says "waiting for equipment" and then turns back on about 60 seconds later.

    What gives? Previous VP 8320 did this too, not nearly as often as the Prestige though (once in a blue moon). Can't imagine what the thermostat thinks it's doing by short cycling the furnace in the middle of bringing the temp up.

  2. #2
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,797
    Its the digital programming, and the temp sensor in the unit. typical behavior for them.
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  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,613
    Interesting. Didn't think that was typical. Never heard that complaint before as a matter of routine. Wonder if the furnace dropped 24v to the stat briefly. Some brands will do that if the limit opens. Had a VP IAQ owner complain the other day about it and it was the limit opening.

  4. #4
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,508
    Odd that the limit would open on low heat but not on high. A way to check to no 24V theory is shut off power to the unit and see if you get the waiting on equipment message.

    If you are dealing with a limit switch issue, how big is the equipment in relation to your ductwork? Have you verified blower speed and temp rise?

  5. #5
    Join Date
    Aug 2012
    Location
    NE wisconsin
    Posts
    404
    That stat can be powered from any 24 volt source, just give it a dedicated transformer then it won't care what the limit does.

  6. #6
    Join Date
    Oct 2002
    Location
    Hamden Ohio
    Posts
    249
    Change the cycles per hour,I don't remember which way. Mine done that when I turned it up very much.

  7. #7
    Join Date
    Jun 2009
    Location
    Northwest IN/Chicago
    Posts
    268
    If it were losing 24v the screen would go out, backup battery only retains the memory in these stats, doesn't power the screen. As for the high limit theory, the temp rise is 38-41 degrees in low and high fire (furnace calls for 30-60)

    Wonder if it has something to do with the furnace being oversized, really doesn't even need 2nd stage. 1st can hold 72 at -15 running almost continuous...so maybe the thermostat knows that and thinks it will overshoot or something and kicks the heat off. Got both stages set to 3 CPH.

  8. #8
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,508
    72 @ -15f in 1st stage is nuts. What is design temp for your area? How big is that furnace?

  9. #9
    Join Date
    Jun 2009
    Location
    Northwest IN/Chicago
    Posts
    268
    Quote Originally Posted by 54regcab View Post
    72 @ -15f in 1st stage is nuts. What is design temp for your area? How big is that furnace?
    Design temp is around 0. It's an 80k 80%er, puts out 41,000 BTU's in low fire. A/C is sized for a desert too. (part of why I put the Prestige in, trying to fix the installers screw ups)

    I wonder if the Honeywell's do this on properly sized two stage systems as well. I remember all the way back to the Chronotherm IV doing weird stuff with cycling off before hitting setpoint too.

  10. #10
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,797
    Once you set it and forget it. It will operate normally. Well, somewhat normally, since you seem to have a grossly oversized furnace.

    The IAQ senses both ambient heat, and IR heat.
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  11. #11
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,508
    Quote Originally Posted by Gus-Herb94 View Post
    Design temp is around 0. It's an 80k 80%er, puts out 41,000 BTU's in low fire. A/C is sized for a desert too. (part of why I put the Prestige in, trying to fix the installers screw ups)

    I wonder if the Honeywell's do this on properly sized two stage systems as well. I remember all the way back to the Chronotherm IV doing weird stuff with cycling off before hitting setpoint too.
    Whoa, 41k keeping a house warm down to -15f outside. Is the house small or super insulated? Seeing this makes the whole oversizing thing really hit home... A simple 50k single stage furnace would have done the job...

  12. #12
    Join Date
    Jun 2009
    Location
    Northwest IN/Chicago
    Posts
    268
    Quote Originally Posted by beenthere View Post
    Once you set it and forget it. It will operate normally. Well, somewhat normally, since you seem to have a grossly oversized furnace.

    The IAQ senses both ambient heat, and IR heat.
    Yeah I usually do set it and forget it, but I set it back 2-4 degrees when nobodies gonna be around all day (nice to use my phone to turn it up)

    Quote Originally Posted by 54regcab View Post
    Whoa, 41k keeping a house warm down to -15f outside. Is the house small or super insulated? Seeing this makes the whole oversizing thing really hit home... A simple 50k single stage furnace would have done the job...
    Its the upstairs, which is 1,300 sqft. R30 in the attic R19 walls. Did a cheap load calc almost a decade ago and came out around 30,000 BTUs @ design with 70 in -10 outside and the attic was R19 at that time.

  13. #13
    Join Date
    Nov 2001
    Location
    Seattle, WA
    Posts
    7,819
    You can play with the cycle per hour but most likely the thermostat, among other things, is still in the process of learning. I'd go with a reasonable CPH then leave it alone for 4 or 5 days or more until it learns your house.
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

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