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-   -   Digital Thermostat Conversion, no display (https://www.askmehelpdesk.com/showthread.php?t=282771)

  • Nov 19, 2008, 08:44 AM
    rfields109
    Digital Thermostat Conversion, no display
    I have a 20 year old honeywell dial thermostat with 4 wires, Red Green White and Yellow connected.

    I purchased a Honeywell T8001F programmable and connected the RED wire to the R connection, White to W, Yellow to Y and Green to G.

    There are other wire terminals like B and O .

    Once connected the unit is dead, no display and acts as if there is no power. I have voltage coming in ut am wondering if it's enough to drive the unit. This particular unit does not use batteries.


    A schematic would be excellent! Honeywells installtion instructions and diagnostics are horrible and I'm hoping you folks can help.

    Have a great day all.
  • Nov 19, 2008, 10:33 AM
    dac122

    Lets first get power to the unit.

    Sounds like your Red is 24VAC hot and connected properly to the R terminal. You now need to connect your 24VAC common wire to the C terminal to properly power the tstat. Do you have another wire than the Red Green White Yellow mentioned above?
  • Nov 19, 2008, 11:12 AM
    rfields109
    There is a blue wire that is not connected to anything and it doesn't appear to be used. Looks like a spare.
  • Nov 19, 2008, 11:28 AM
    dac122

    Could be your missing common.

    I hesitate to tell folks to just hook it up, so best is to follow that back to wherever and verify it is your common or hook a multimeter to it and Red to verify 24VAC.
  • Nov 19, 2008, 01:47 PM
    hvac1000
    You are missing the C common wire


    From your Honeywell manual.

    The T8001F, T8024F Thermostat is powered directly
    from the system transformer. Batteries are not required
    because setpoints are held permanently by non-volatile
    memory.
    Your manual

    http://customer.honeywell.com/techli...it/69-1465.pdf


    Honeywells manuals are some of the best in the industry but you need to read them carefully. The wiring diagrams are also great.
  • Nov 20, 2008, 07:42 AM
    rfields109
    The PDF link is awesome, Much more detailed than what came in the box. I needed that schematic and now I can get this thing working... Thank You ALL.
  • Nov 20, 2008, 08:15 AM
    KISS

    Hvac1000:

    Honeywell manuals need improvement. I've even complained. Not a blip back.

    Here is a perfect example from the VisonPro Install guide

    0350 Heat pump compressor lockout
    0 No heat pump compressor lockout
    [Other options: outdoor sensor below 15, 20, 25, 30, 35, 40°F (-9.5°C to 7°C)]

    0360 Heat pump auxiliary lockout
    0 No heat pump auxiliary lockout
    [Other options: outdoor sensor below 40, 45, 50, 55, 60°F (4.5°C to 15.5°C)]

    The word outdoor sensor below is missing.

    Documentation is a PAIN to write.
  • Nov 20, 2008, 10:25 AM
    hvac1000
    Glad it worked out for you.

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