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  1. #1

    Two stage t-stat, yes or no?

    I recently purchased a 2-stage Lennox Elite furnace. The installer set the control board for a 15-minute timed stage 1 fire (10-min is factory default). I do not have a 2-stage t-stat.

    Most discussions on this board say that a 2-stage t-stat is best but I am pondering this after trending the furnace operation for a month.

    Once my home is at the set temp, the furnace fires at stage-1 for 9-13 minutes with about 3 cycles/hour. This varies upon outdoor temps, sunlight, etc. The only time stage 2 is fired is when there is a large temp swing such as after an overnight setback or a demand increase in room temp.

    In this normal operation scenario: 1)Is there a potential for fuel savings using a smart t-stat? 2)Any other advantages since maintain temp operation is stage 1?

    If this is worth considering I'll ask the installer to come back to suggest and install a new t-stat. Thanks for your thoughts.

  2. #2
    Join Date
    Jun 2003
    Location
    Florida
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    9,548
    It doesn't sound like you need one as long as it's comfortable for you. I don't see any savings.....JMO
    If everything was always done "by the book"....the book would never change.

  3. #3
    Join Date
    Dec 2007
    Location
    oregon
    Posts
    885
    If it ain't broke, keep fixing it till it is! If your comfy,why change? most two stage stats time out for 2nd stage, just like your furnace dip switch settings, unless a large temp drop is seen by the stat. ( depending on brand) Two stage stats are cool, but in your case a two stage stat probably won't save you alot, I would reccomend to keep the one you have .
    Genius = The guy who can do anything...except make a living!

  4. #4
    Join Date
    Dec 2002
    Location
    Toledo, Ohio, United States
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    12,921
    Twilli always uses a two stage stat, but hey thats Twilli
    No Heat No Cool You need Action Fast

  5. #5
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,773
    First. 2 stage furnaces are for comfort, not to save on the heating bill.
    So you bought a comfort furnace, and defeated most of its ability.

    A 2 stage stat will keep it in first stage as long as possible, helping to keep all the rooms at a temp closer to the set point on the stat.

    Its a comfort thing, not a money saving.

    There's a couple pro's on here that had single stage stats on their 2 stage furnaces first. Later they put on 2 stage stats. All of them seen improvement in over all comfort in the house.
    If your comfort isn't worth a 2 stage stat, why waste the money on a 2 stage furnace.
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  6. #6
    Join Date
    Dec 2002
    Location
    Toledo, Ohio, United States
    Posts
    12,921
    Twilli says beenthere smart man, maybe you've beenthere before.
    No Heat No Cool You need Action Fast

  7. #7
    Join Date
    Dec 2007
    Location
    Carrollton,GA
    Posts
    39

    2-stage...

    I'm also about to have a 2-stage stat installed, as I just had a Trane VS 2-stage furnace installed. I understand the role the stat plays while heating, but does it contribute as much during the cooling process or is that mostly board control settings with the Comfort-R "ramp up" schedules?

  8. #8
    Join Date
    Dec 2007
    Location
    oregon
    Posts
    885
    To benifit from comfort r you should choose the tcont802 or 803. If you have a xl16i use the 803, if you have a gas furn and heatpump combo use the Honeywell 9000 IAQ stat. What kind of outdoor unit do you have?
    Genius = The guy who can do anything...except make a living!

  9. #9
    Join Date
    Dec 2007
    Location
    oregon
    Posts
    885
    As a norm we install two stage stats on all two stage equipment on new installs.
    Genius = The guy who can do anything...except make a living!

  10. #10
    Join Date
    Dec 2007
    Location
    Carrollton,GA
    Posts
    39

    Xe1000

    Quote Originally Posted by geodude View Post
    To benifit from comfort r you should choose the tcont802 or 803. If you have a xl16i use the 803, if you have a gas furn and heatpump combo use the Honeywell 9000 IAQ stat. What kind of outdoor unit do you have?
    My Outdoor Unit is a Trane XE1000 (14.5 years old). I'm actually getting ready to have the HVAC guys come out to run the load calc numbers, and recommend an upgrade. Any suggestions: XR14, XL14, 15 or 16i? I want to get a stat that will work with the current XE1000, as well as my upgrade. Thanks!

  11. #11
    Join Date
    Feb 2003
    Location
    S.W. PA
    Posts
    3,298


    2 stage stat for 2 stage equipment

  12. #12
    Join Date
    Dec 2007
    Location
    oregon
    Posts
    885
    All the stats I mentioned are two stage and should be used with a two stage furnace, They will work any of the outdoor units you listed. I reccomend the most energy effcient equipment your budget will allow you to purchase.
    By the way dhvac, funny video
    Genius = The guy who can do anything...except make a living!

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