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Thread: Upgrading Honeywell Thermostat

  1. #1
    DIY Member TheOak's Avatar
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    Question Upgrading Honeywell Thermostat

    I have a Honeywell 8401C1007.

    The installation manual can be found here.

    When I pull the unit off of the wall, I have the following wires from top to bottom:

    W white
    Y yellow
    G green
    R red
    C this wire is actually blue

    I would like to upgrade to the Honeywell touch screen 8110U.

    The installation manual can be found here.

    On page 4 of the PDF I assume I would wire it using the 1H/1C System (1 Transformer) where I would keep the jumper installed.

    The installer setup begins on page 6. I think it is pretty intuitive expect for on page 7.

    What is "Change over valve (O/B terminal)"? The default is O/B terminal control valves in cooling. The other setting is the same but in heating.

    Any recommendations on how I would set this up?

    Thanks ...

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    What kind of heating/cooling do you have? Conventional or a heat pump?
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Plumber jimbo's Avatar
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    The changeover ( reversing ) valve is a component of a Heat Pump system, which apparently you do not have. Depending on what brand of heat pump, you have to energize the reversing valve in either cool mode or heat mode. Older thermostats had a B (blue) terminal, or an O (orange) or both. Electronic stats like yours take care of this in set-up so don't need two terminals.

    You do not have a heat pump, so this is N/A for you.

    The C terminal, if used on your old model, was a power lead for the stat. Your new one has the option of being powered solely by the xfmr, using that C wire. The batteries back up the program. If you didn't have that wire, then the stat is powered by the batteries and will stop working if the batteries die.

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    DIY Member TheOak's Avatar
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    I have a natural gas furnace and electric A/C. Both are controlled with my current thermostat by setting it to cool or heat accordingly. The furnace sits in my garage. The A/C sits outside. The two are "combined" or integrated with a "blower"(? not sure if that is the technical name).

    Edit:

    I do not have a heat pump. The furnace is a Lennox system installed in 99. I believe it is rated as 80% efficient.

    The A/C unit is Lennox too. Not sure on the SEER rating.
    Last edited by TheOak; 10-21-2008 at 07:15 AM.

  5. #5
    DIY Junior Member tedfrk's Avatar
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    First wire it with white wire to W,Green To G,yellow to Y,red to R and Rc jumped together,and now blue to c .make sure you have an 80% furnace.do you have metal pipe as the flue or white pvc?if its pvc its a 90%.and set up the t-stat accordingly if you dont it wont work correctly.and dont worry about the other terminals on the t-stat.

  6. #6
    DIY Member TheOak's Avatar
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    Quote Originally Posted by tedfrk View Post
    First wire it with white wire to W,Green To G,yellow to Y,red to R and Rc jumped together,and now blue to c .make sure you have an 80% furnace.do you have metal pipe as the flue or white pvc?if its pvc its a 90%.and set up the t-stat accordingly if you dont it wont work correctly.and dont worry about the other terminals on the t-stat.
    I have metal.

    On page 8 of the manual, for setting 240, "First Stage Heat Cycle Rate", there is a setting of "5" for "Gas or oil furnaces of less than 90% efficiency". I assume then I would naturally select 5.

    Thanks for the wiring details. That is what I planned to do. Perfect!

  7. #7
    DIY Junior Member tedfrk's Avatar
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    yes set it up for number 5

  8. #8
    DIY Member TheOak's Avatar
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    Thumbs up

    Quote Originally Posted by tedfrk View Post
    yes set it up for number 5
    Thanks for all of your help!

  9. #9
    DIY Junior Member tedfrk's Avatar
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    and dont forget to shut your emergency switch off before you begin so you dont cause more problems.

  10. #10
    DIY Member TheOak's Avatar
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    Totally, I plan on turning the power off to the a/c/furnace prior.

  11. #11
    DIY Member TheOak's Avatar
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    Could I:

    1. Insert batteries into thermostat.
    2. Setup thermostat.
    3. Turn off power to furnace.
    4. Install wires to new thermostat base.
    5. Install thermostat to base.

    So basically my question is for the initial setup does it need to be connected to the furnace, or can I do the "armchair" feature, set up the thermostat first, and then once all the wires are hooked up mount the thermostat to its base and away it goes?

    Make sense?

    Thanks ...

  12. #12
    DIY Junior Member tedfrk's Avatar
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    you can do whatever you want to the t-stat before you install it.just dont forget to turn the emergency switch off..and if you have enough wire cut off the existing wire that was stripped so you dont have any problems with them breaking if someone stripped them wrong.

  13. #13
    DIY Member TheOak's Avatar
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    What do you mean by "emergency" switch? Do you mean the circuit breaker? Please expand ... thanks ...

    Edit:

    Nevermind ... figured it out ... thanks.
    Last edited by TheOak; 10-27-2008 at 06:51 PM.

  14. #14
    DIY Member TheOak's Avatar
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    Just did the swap.

    Pretty painless ...

    It was a little quirky to program sometimes. For example, for 6 days of the week I only had 2 modes, a wake and a night. However, for one day only I had a wake, leave, return, and night. Sometimes in setting the just the 2 modes common for all the days, the 2 would get wiped out on the one day. Real easy to program otherwise ...

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