Installing 24 volt WiFi Thermostat on millivolt stoves

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

  1. dougzdog

    dougzdog
    Member 2.
    NULL
    

    Sep 29, 2012
    1
    1
    This is safe for millivolt stove? Do all thermostats have the jumper?
     
    smwilliamson likes this.
  2. DBCOOPER

    DBCOOPER
    Minister of Fire 2.
    NULL
    

    Jan 23, 2010
    500
    100
    Loc:
    Stowe, Pa
    On a gas stove the millivolt signal is generated by the pilot light acting on a thermocouple which makes a voltage that lets the gas valve open. Once the pilot light is established then a thermostat closes its contacts the gas valve will open. It works the same as the proof of fire thermocouple works on a Quad. I don't know of any pellet stoves that use a pilot light so they don't require a millivolt thermostat. Any switch closure should work, be it a dry contact thermostat, relay or even timer. At least that's the way it is with my Quad.Same thing for a gas stove with a standing pilot, any dry contact will make it come on. Intermittent pilots are a different story.
     
  3. DBCOOPER

    DBCOOPER
    Minister of Fire 2.
    NULL
    

    Jan 23, 2010
    500
    100
    Loc:
    Stowe, Pa
    The R and C provide the power for the thermostat. Inside the thermostat are small relays that open and close based on the thermostat settings. The R and RH are jumpered because in a typical heating system everything is running off of one transformer so it saves running an extra power wire to RH. So if you remove the jumper you end up with a switch between RH and W and when the stat calls for heat that switch closes and it's not connected to anything but the wires that you connect to RH and W. So yes it's safe to do that on a millivolt stove.
     
  4. romaniuk

    romaniuk
    New Member 2.
    NULL
    

    Mar 7, 2015
    2
    0
    Loc:
    Northwest Edmonton, Alberta, Canada‎
    Yes, its really good.
     
  5. smwilliamson

    smwilliamson
    Minister of Fire 2.
    NULL
    

    Dec 28, 2009
    4,527
    799
    Loc:
    Southcoast, MA
    That's fine so long as the run to the stove is short from the tstat. You cannot reliably send a millivolt signal very far that's why we use 24v
     
  6. Don2222

    Don2222
    Minister of Fire 2.
    NULL
    

    Feb 1, 2010
    8,017
    494
    Loc:
    Salem NH
  7. Arti

    Arti
    Feeling the Heat 2.
    NULL
    

    Feb 14, 2014
    379
    87
    Loc:
    South West Wisconsin
    I remember reading the directions one time that if you increase the wire size to #14 wire the max length was only 75 feet for a Honeywell millivolt system.
    This usually isn't an issue in residential settings but in a commercial settings it can be a problem.
    Just out of curiosity are these really Millivolt controls in Pellet stoves or does the thermostat just open and close a circuit on the control board?
    Haven't seen a lot of Pellet stoves but out of the dozen brands I've been into not a one has a Thermopile in it to create a millivolt signal.
    I suspect that Millivolt compatible Thermostat is specified because they want a dry contact to control the Pellet Stove?
     
  8. dpc

    dpc
    New Member 2.
    NULL
    

    Jul 16, 2015
    1
    0
    Loc:
    kirkland, wa
    Say that I can power the WIFI thermostat, with 24vac. Can I use a relay to convert my WIFI thermostat heat control output line signal, on R and W I think, to control my millivolt fireplace circuit?

    I have a millivolt circuit that runs from the fireplace to a wall switch. The switch turns my fireplace flame on and off. I want the thermostat to do this in the future.

    Anyone know where I can find the perfect relay for this?
     
  9. Don2222

    Don2222
    Minister of Fire 2.
    NULL
    

    Feb 1, 2010
    8,017
    494
    Loc:
    Salem NH
  10. smwilliamson

    smwilliamson
    Minister of Fire 2.
    NULL
    

    Dec 28, 2009
    4,527
    799
    Loc:
    Southcoast, MA
    Use the parts I outlined. It will work.
     
  11. smwilliamson

    smwilliamson
    Minister of Fire 2.
    NULL
    

    Dec 28, 2009
    4,527
    799
    Loc:
    Southcoast, MA
    That is correct. Whatever the distance is to the stove we have to double it for send and return
     
  12. WoodPorn

    WoodPorn
    Minister of Fire 2.
    NULL
    

    Aug 24, 2009
    1,503
    220
    Loc:
    South of the beloved Patriots
    Scotty, you're so smart!
     
  13. WoodPorn

    WoodPorn
    Minister of Fire 2.
    NULL
    

    Aug 24, 2009
    1,503
    220
    Loc:
    South of the beloved Patriots
    And one heck of a model american.....
     
    smwilliamson likes this.
  14. ispt17

    ispt17
    New Member 2.
    NULL
    

    Sep 20, 2015
    1
    0
    Loc:
    buick
    Hello, I am new here...:)...I own a Osburn 5000 pellet stove and I bought a Nest 3 gen thermostat....
    1. From stove I got 2.5 - 3.5 V
    2. Nest request 24 V
    can I do same like in pictures, is safe for my pellet stove or I do need a relay too?
    thank you
     
  15. Westwind

    Westwind
    New Member 2.
    NULL
    

    Nov 10, 2015
    1
    0
    Loc:
    St. Clair, MI
    I am new to this board. I have been reading this thread and trying to understand this. I am truly a novice . I have a vacation home that I recently purchased. It has a SCI CEM24 talking thermostat. It requires a landline to communicate with. Since I do not want a landline I have been experimenting with a gateway that connects my wiring with a cell phone. The thermostat will answer but will not recognize the tones from the cellphone. This thermostat controls a gas fireplace insert. I bought a Honeywell wifi thermostat as in the OP but was told by customer service that it won't work because it has a millivolt contact. My question is to do the conversion as described, I already have an R and a C wire at the thermostat. What would I need to do from there?
     
  16. naren

    naren
    New Member 2.
    NULL
    

    Nov 14, 2016
    4
    1
    Loc:
    New England
    I just bought Harman XXV stove. This thing works like a champ. I would like to have the stove connected to wi-fi. There are two option described in this thread. One is Honeywell Thermostat and Ecobee Stat-02. I was wondering if I could use Ecobee3 model in one of the the options.
     
  17. smwilliamson

    smwilliamson
    Minister of Fire 2.
    NULL
    

    Dec 28, 2009
    4,527
    799
    Loc:
    Southcoast, MA
    Yes, but when temp is achieved on the stove it will error #4 and go to shut down mode. It will start back up when the call comes back and the error will go away till the tstat is satisfied again. No harm will come to the stove, it's just that Harman uses a thermistor that always has a circuit. When the tstat opens the circuit opens and the error shows up.
     
  18. Don2222

    Don2222
    Minister of Fire 2.
    NULL
    

    Feb 1, 2010
    8,017
    494
    Loc:
    Salem NH
    Harman has a technical bulletin on how to use their stoves with a T-stat. They suggest to make the set temp on the T-stat to 95 Deg and then set the stove to the desired room temp.
    I connect the Lowe's Iris T-stat with swing setting set to 2 degrees and connect the 2 wires in series to one of the room probe wires on my workshop's Harman Advance. Then I can manually turn the stove on and off with my iPhone or use a schedule and see what the temp in the room is on my iPhone. It works very well unless the stove runs out of pellets, then I have to reset the stove. :)
     

    Attached Files:

  19. naren

    naren
    New Member 2.
    NULL
    

    Nov 14, 2016
    4
    1
    Loc:
    New England
     
  20. naren

    naren
    New Member 2.
    NULL
    

    Nov 14, 2016
    4
    1
    Loc:
    New England
    Looking at wiring diagram in the OP does the 24v wire goes Rh, W and C in the thermostat?
    Could you mind drawing a wiring diagram to connect the iris in series with the room probe?
     
  21. Don2222

    Don2222
    Minister of Fire 2.
    NULL
    

    Feb 1, 2010
    8,017
    494
    Loc:
    Salem NH
    Cannot use a 24v T-Stat unless you build a relay.
    A millivolt T-Stat connected to Rh & W works well.

    Here is the Harman Bulletin:)
    https://www.hearth.com/talk/threads/thermostat-to-harman-p43.152720/#post-2049693

    Here is my diagram
    https://www.hearth.com/talk/threads/wood-pellet-stove-connecting-a-thermostat-to-the-avalon-astoria.72930/#post-921673
     
  22. naren

    naren
    New Member 2.
    NULL
    

    Nov 14, 2016
    4
    1
    Loc:
    New England
    I bought the RTH 8500 Tstat on the Black Friday deals at 80 bucks hoping to work with out any issue if I do the wiring as drawn in OP. XXV stove did not work when I connected the relay directly to the male disconnects where the room temp sensing probe was connected, the stove did not turn on when it called for heat. I double checked all the the wiring and also did a continuity check to make sure relay is working properly. It was wired properly but still stove did not turn on. I was desperate to make this work and connected my room temp probe in series with the relay ( this post mention in by Don) combing with the other setup in the OP. 3 hrs later everything looks to be working fine with Wifi tstat. Thanks smwilliamson and don2222.
     
    bogieb likes this.
  23. Lake Girl

    Lake Girl
    Moderator 2.
    NULL
    
    Staff Member

    Nov 12, 2011
    6,941
    1,440
    Loc:
    NW Ontario
    Nice that you are up and running!
     
  24. bogieb

    bogieb
    Minister of Fire 2.
    NULL
    

    Oct 31, 2014
    2,540
    938
    Loc:
    South Central NH
    Although my t-stat on the P43 isn't wifi, I have it set up with the temp prove in series and it works great. I set the stove temp at 75 and my thermostat at what I want the temp to be (68-69 currently) and it works great. I did find that when hooked up this way, I cannot use room temp / manual with the stove, which is what I would normally do in the extremely cold weather. However, if I want to run the stove constantly, with a constant high fan, I just put it in stove temp / auto and use the feed rate to modulate the temp in the house.
     
  25. dbuff

    dbuff
    New Member 2.
    NULL
    

    Jan 27, 2017
    1
    0
    Loc:
    boston, ma
    Hi I am new here. I have a Napoleon NPS45 pellet stove. I find it frustrating reading up on what the definition of a millivolt system is and how easy the stove plugs into my Honeywell rth2310b and works fine as it would not work if the power was out. I am looking to install an ecobee3 lite but would use a nest or lyric whatever would work. I have a goodman furnace/airhandler that is only wired to the thermostat Rh and W at this point for forced hot air. I would like to run a new 5 wire line from the furnace to the new thermostat so that I can utilize the fan as well as have the Y and Rc for central air at some point. It would also include a C wire so that I can power the thermostat from there. I would then want to wire the pellet stove as well but would want it to be the primary heat source as pellets are cheaper than propane with the inefficient furnace. from use a wiring diagram I think it would just need to plug the stove into W and Rh of the ecobee and wire the furnace to w2 to make it the second stage or emergency heat. I am sure it doesn't work that way so I would also like to know what kind of relay I would need. I am guessing if I can use the power from the furnace to power the thermostat that I wouldn't need the transformer for power. Any information is greatly appreciated.
     

Share This Page