Installing 24 volt WiFi Thermostat on millivolt stoves

smwilliamson Posted By smwilliamson, Sep 19, 2013 at 5:39 PM

  1. James76

    James76
    New Member 2.
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    Jan 29, 2017
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    Loc:
    Huntsville
    Hey folks, I recently was successful is installing the Honeywell RTH6500 on my napolean gas stove.

    One thing I was not anticipating was the unit was cycling on 5 to 6 times per hour even though the desired temp was being maintained. Most times the stove would only come on for a few mins. It is my understanding that short cycling is not good for gas stoves.

    I've done some research and that heating cycle rates settings may be the culprit. Seeing that there appears to be folks who have successfully installed programmable thermo's on their stoves I am wondering if anyone else has run into this problem or has any suggestions?

    Thanks
     
  2. Arti

    Arti
    Feeling the Heat 2.
    NULL
    

    Feb 14, 2014
    381
    89
    Loc:
    South West Wisconsin
    I believe it is Function number 5 in the Setup Menu that sets the cycles per hour.
    This thermostat is called a comfort tstat it doesn't really heat to a set point it calculates how many minutes the unit needs to run an hour to maintain a temperature and then breaks this up into 3,5,9, or 1 cycles per hour and then runs so many minutes per cycle. If you look in the install manual and find the setting for steam or hot water it will cut the cycle rate down for you.

    Also you may want to look at the smart response settings.
    I'm not familiar with this particular model thermostat but it may have an adjustable swing temp setting in it although most honeywell thermostats don't. They maintain within approx 1/2 degree of set temp, I find most wood/pellet stoves live a 2 or 3 degree swing.
     
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  3. RavingZeus

    RavingZeus
    New Member 2.
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    Feb 22, 2017
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    Loc:
    Montreal

    Hi, I have a Harman P43

    If i refer to the Technical bulletin of Harman Tstat need to be connected in serie with the probe.
    If I use the schematic in the first post to connect a WIFI Tsat with the relay and a 24volt power source, do I still need to connect the room probe in serie? If yes, were do I put the probe in serie exactly in the diagram?

    Thanks for your help
     
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  4. RavingZeus

    RavingZeus
    New Member 2.
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    Feb 22, 2017
    19
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    Loc:
    Montreal
    Everything works perfectly, just connect the Harman temp probe in serie with the relay output.

    Thanks for the info!


    thermo.jpg
     
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  5. bmwmaw

    bmwmaw
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    Dec 20, 2011
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    Loc:
    Eastern Panhandle, WV
    I have a PF100 furnace with the Harmon wall control. So according to Harman's set back thermostat install I have to wire the Tstat in series with the wall control. Do I have to use the wall control knob? I'd rather just use the programmable Tstat. Are there any advantages/disadvantages to either method?
     
  6. bmwmaw

    bmwmaw
    Member 2.
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    Dec 20, 2011
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    Loc:
    Eastern Panhandle, WV
    Thanks for the good info - just to confirm again, I don't need the relay as long as I remove the R and Rc jumper and am not running very far? I think my Tstat is only going to be maybe 10-15 feet from the pellet furnace.
     
  7. Nigel459

    Nigel459
    Member 2.
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    Oct 24, 2017
    169
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    Loc:
    Ontario, Canada
    Just wanted to reply to this thread to say: The above worked great for me with a Honeywell (Wifi RTH6580) thermostat.

    Wanted to update as I have been searching and searching for something to corroborate my findings (i.e. you might not need the relay, since there's one built in to the thermostat!) and finally stumbled across Arti's posts. If there's a way to update the first post of this thread, which says you need a relay, that would have saved me some time.

    Thanks @Arti! Cheers all and happy thermostatting :)
     
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