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  1. #1

    Question Need Help with Vision Pro IAQ Termstat

    We recently installed a dual fuel oil furnace/heat pump system in our home. Along with the new system, the installer installed a Honeywell VisionPro IAQ thermostat (Model No. TH9421C1004). We've programmed the thermostat for 64 in the evening and 68 in the morning. As we understand it, the auxiliary oil heat should not come on until the outside temperature drops to 35 degrees.

    The problem is that the auxiliary oil heat comes on whenever the inside temperature varies by more than 2 degrees (regardless of the outside temperature). The installer says its because this particular VisionPro model includes a "2 degree droop" function. We've had the installer out a couple of times to try and reprogram the thermostat; however, the problem continues.

    Can someone help us with this problem?

  2. #2
    Join Date
    Aug 2006
    Posts
    112
    the 2 deg. droop function can be programmed out of the control in the installer set up area. call your contractor back and demand someone who knows how to program the control to come set it up as you would like it to run.

  3. #3
    Join Date
    Oct 2008
    Posts
    24
    Quote Originally Posted by referrob View Post
    the 2 deg. droop function can be programmed out of the control in the installer set up area. call your contractor back and demand someone who knows how to program the control to come set it up as you would like it to run.
    sounds like u need your droop set to 5 degree, definitely request a tech who understands the setup of your new t-stat.

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,755
    Do you have the outdoor sensor.

    If you don't have the outdoor sensor.

    You can't lock out the oil furnace or heat pump.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  5. #5
    Been there,

    Yes. We have an outdoor sensor.

  6. #6
    Join Date
    Jul 2008
    Posts
    551
    Then lockout the oil furnace for temps above 35 degrees.

  7. #7
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by referrob View Post
    call your contractor back and demand someone who knows how to program the control to come set it up as you would like it to run.
    Or, get the Installation Manual and program the t-stat the way you want it.

  8. #8

    Check Installer Setting 345

    If 345 = 1, fossil fuel backup will startup if there is a 2 degree droop from actual inside temp to target temp. You can lock out the droop aspect by changing 345 = 0. Then fossil fuel backup will only kick on if outside temp drops below the balance point temp (setting 360).

  9. #9

    Confused Honeywell VisonPRO IAQ

    I also have the Honeywell VisonPRO IAQ TH9421C1004 and have a somewhat similar issue. I don't understand the difference between Functions 0350 and 0360. If I want the Aux Heat (gas) to come On when the temperature outside is below 45 F (instead of the Heat Pump) but without the 2 F "droop" ... I will set Function 0345 to "0" (currently set to "2") and then ... set Function 0350 to 45 F. Correct? Do I have to set Function 0360 to "0"?

  10. #10

    Honeywell VisonPRO IAQ Part 2

    I sort answered myself when I changed Function 0345 to "0" as Function 0360 disappeared from the menu selections. So it seems that now: outdoor thermostat below 50 F, turns on the gas furnace, and above that uses the heat pump.
    On the other hand Option 0346 remained in the menu and I thought that timer was in connection with the 2 F "droop" in Option 2 of Function 0345 (now set to "0"). Can anyone clarify the purpose of the timer in 0346 if 0345 is set to "0"?

    [The outdoor thermostat in the compressor gets the sun directly and reflects almost ten degrees difference in real outdoor temperature. Plus local electricity rate is going up 10% and natural gas is going down. ... thus my experiments with changing the settings].

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,755
    It should still time to furnace, if you have a time set.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  12. #12

    Outdoor Variation for Temp Sensor

    Dagny, I have a similar problem....my outdoor temp sensor seems to randomly vary between 5-15 degree from "real" temp, but downward (40 for real, outdoor sensor says 25). Frustrating.

    Installer has replaced sensor, and now how changed with wire in current wiring carries that signal. Next step, run a new wire (through finished basement - ugh!). But it's really frustrating me.

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