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  1. #1
    Join Date
    Aug 2009
    Posts
    154

    2 thermostats for 1 furnace and ac unit?

    Lennox G61V furnace and Lennox XC21 AC unit... Can two thermostats be installed to control these units (1 on 1st floor and 1 on second). There is no actual zoning in the ductwork.

    AC is the main issue which will hopefully be less of an issue with this new equipment.

    Example: If the 1st floor thermostat is set to 72 degrees and the floor is 72 degrees - there is no call for ac. But if the 2nd floor is 75 degrees can I have a 2nd thermostat on the 2nd floor set to 72 degrees that will call for ac again. I know the first floor might end up even cooler but thats ok.

    Can this work? If so will the Honeywell IAQ thermostat work - it came highly recommended... if not what should I go with.

    Thanks

  2. #2
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    I don't understand why you just can't set your (1) thermostat to the setpoint temp that makes you comfortable. If you need the bedroom a few degrees cooler in the summer, lower the setpoint for sleeping.

    Good luck with the new system.

  3. #3
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,770
    Either just install the stat on the second floor.

    Or, install sensors, and use it as an averaging thermostat.

    2 stats can cause issues. Specially when someone forgets the second floor stat could be calling in spring. And then turns the first floor stat to heat and turns it up.
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  4. #4
    Join Date
    Sep 2009
    Posts
    382
    I perfectly understand what you are trying to achieve. 2nd floor can get cold (winter) or hot (summer) at a different rate than the 1st floor, we have done this re-wiring before, although it's rarely requested by HOs.

    What we did was putting in a 4P3T toggle switch between the 2 stats.

    Quote Originally Posted by tomwk View Post
    Lennox G61V furnace and Lennox XC21 AC unit... Can two thermostats be installed to control these units (1 on 1st floor and 1 on second). There is no actual zoning in the ductwork.

    AC is the main issue which will hopefully be less of an issue with this new equipment.

    Example: If the 1st floor thermostat is set to 72 degrees and the floor is 72 degrees - there is no call for ac. But if the 2nd floor is 75 degrees can I have a 2nd thermostat on the 2nd floor set to 72 degrees that will call for ac again. I know the first floor might end up even cooler but thats ok.

    Can this work? If so will the Honeywell IAQ thermostat work - it came highly recommended... if not what should I go with.

    Thanks

  5. #5
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,037
    If you want to keep the temperature closer between floors try running the fan continuously. Yes doing this will cost you in electrical use due to the fan running 24/7, but compared to what it will cost you to overheat or overcool the offending floor I think you'll find it a break even at worse.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  6. #6
    Join Date
    Nov 2004
    Location
    redlands, ca
    Posts
    49
    We have been using the Honeywell HD thermostat. It comes with a remote. The actual thermostat is mounted usually upstairs and the remote that comes with it, the homeowner keeps downstairs. Our customers love it.

  7. #7
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,038
    Quote Originally Posted by airredlands View Post
    We have been using the Honeywell HD thermostat. It comes with a remote. The actual thermostat is mounted usually upstairs and the remote that comes with it, the homeowner keeps downstairs. Our customers love it.
    Is that the wireless?

    We had a class on the wireless stats. Good stuff. It was called the poor man's zoning. Just carry the stat up stairs at night and down stairs for breakfast.

    I've seen the toggle switch twice. One was a summer winter job, and the other was an upstairs downstairs job. They work well also.

    My vote is the wireless. Very cool stuff.

    Or see if someone could do a two zone job with dampers.
    Beware of advice given by some guy on the Internet.

  8. #8
    Join Date
    Aug 2009
    Posts
    154
    I don't mind running the fan more often since it will have the ecm motor - supposedly uses 2/3 less electric, so running it 24/7 would probably no more money than my current non ecm motor - not that I really want to go out of my way to run it non-stop.

    I saw that the Honeywell Vision Pro IAQ thermostat has a fan setting choice called "circulate" that runs the fan 35% percent of the time when there is no call for heat or ac. I also saw in the owners manual online that this thermostat works with remote indoor sensors. I will have to ask my installer about these. He had wanted to just install 2 thermostats, which may not be wrong but I think this idea might be better.

  9. #9
    Join Date
    Aug 2009
    Posts
    154
    I just read more about the remote indoor sensors for the HW IAQ thermostat. These sound great, but I did read that if you use more than 1 then you have to use 4 to make it work.

    I guess I could just have 1 thermostat installed with 4 indoor remote sensors. It should average all the temps, and combine that with the fan circulate feature that runs it 35% of the time when there is no call for heat or ac... this should drastically improve the setup.

    Thanks again everyone.

  10. #10
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,038
    Just use one wireless stat. Just have to get used to carrying it up and down stairs.
    Beware of advice given by some guy on the Internet.

  11. #11
    Join Date
    Aug 2009
    Posts
    154
    I just think that for me personally it would get annoying to carry around 1 wireless thermostat. I personally think I would like to use more than 1. Is it true that you have to use either 1 or 4. It can't be just 2 or 3?

  12. #12
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,038
    Quote Originally Posted by tomwk View Post
    I just think that for me personally it would get annoying to carry around 1 wireless thermostat. I personally think I would like to use more than 1. Is it true that you have to use either 1 or 4. It can't be just 2 or 3?
    Don't know. I've only installed one. And we zoned that. Big house. Zoned the kitchen from the living room.
    Beware of advice given by some guy on the Internet.

  13. #13
    Join Date
    Mar 2007
    Location
    Madison, Wisconsin
    Posts
    2,263
    Why go through all the headache? Why not just go ahead and zone it?
    I r the king of the world!...or at least I get to stand on the roof and look down on the rest of yall

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