# Millivolt thermostat ?



## DBCOOPER (Feb 3, 2013)

I have seen several people tell people that they need a millivolt thermostat. A millivolt thermostat works with a standing pilot gas valve system. Several thermocoulpes in series generate a voltage while sitting in a pilot flame. It works like the thermocoulpe in some stoves work to prove a fire is established. They usually make .75 volts. So a milivolt thermostat is designed for millivolts not 24 volts ac like my quad uses in its control circuit. I have never seen a pellet stove with a standing pilot light. Are there any stoves that the manual specificly requires a millivolt thermostat?


----------



## imacman (Feb 3, 2013)

This is right from the Englander manual for my stove:
"An external thermostat..........can be used on our Pellet/Corn/Multi-fuel units as long as it is a low-voltage that works with millivolt systems." 

Most stoves that I've seen or heard about use a millivolt stat.


----------



## DexterDay (Feb 3, 2013)

A lot do say millivolt systems. But Quad States a 12 volt AC stat. 

I see what your saying DB... Makes sense. Although, it is printed in many manuals that way.


----------



## jtakeman (Feb 3, 2013)

Most of these control boards made by ACE use micro processors(Enviro-Breckwell-Kozi-ect.). Pretty sure they are using 5V which might be to low for a 24V stat. But I do see some of the stats rated for pellet stoves also work on millivolt and 24V systems.


----------



## tjnamtiw (Feb 3, 2013)

IMHO, I think that they are really saying that you only need a thermostat that can 'handle' millivolts, meaning the contacts (of what ever kind) are capable of handling only low voltage and resultant current.  Yes, Quad says 12 volt stat.  Did you ever have luck finding such an animal?


----------



## jtakeman (Feb 4, 2013)

Not sure its because of the lower voltage, probably more like the resistence is too high within the stat?


----------



## ekarlis (Feb 4, 2013)

I was told by a distributor that Honeywell stop making millivolt stats & all the new stats are digital 24 volts. All the control boards that I have seen have a transformer that generates 24 volts for the stat. The stat is merely a switch
& the power comes from the board & it is not millivolts. The last millivolt system I installed was in 1970's. The current
furances have been using hot surface ignition w/24volt system. This has been a confusing issue w/ millivolt systems,
but as far I am concerned millivolt systems are long gone & dead for stat use. Hope this helps


----------



## SmokeyTheBear (Feb 4, 2013)

Don't tell Honeywell  http://www.homedepot.com/buy/honeyw...ogrammable-thermostat-ct33a.html#.UQ_WTSAbRFQ


----------



## silverfox103 (Feb 4, 2013)

My Harman PP38 (1997), made does require a minivolt thermostat.  Digital thermostats will not work, that I know.  It's a very inexpensive thermostat, I think they have them at HD for around $12.

Tom C.


----------



## ekarlis (Feb 5, 2013)

Called Honeywell & spoke to a tech. He said that the 750 millivolt stats are compatable to a 750 volt system.
They are derated 24volt stats. Also he said that they can not afford to have a separate assembly line for
750 millivolt stats


----------



## Thaddius Wenderoth (Feb 5, 2013)

The thermostat I use is an internet connected stat from Hunter Fan. It states it will work with both systems. Heres the link and what it says about it.


http://www.hunterfan.com/Innovations/Universal-Internet-Thermostat/

The Hunter Universal Internet Thermostat works with most HVAC (Heating, Ventilating and Air Conditioning) system you have—conventional, heat pump, radiant, you name it:

Electric air conditioning
Up to 2 Stage Heat/2 stage Cool systems
Single and two stage heat pumps with auxiliary heat
Gas, electric and oil furnaces
Gas and oil fired boilers
2 and 3 wire hot water/radiator systems
24 Volt and Millivolt systems
AC or battery power NOT FOR USE with 110/220 volt electric baseboard heat


----------



## SmokeyTheBear (Feb 5, 2013)

ekarlis said:


> Called Honeywell & spoke to a tech. He said that the 750 millivolt stats are compatable to a 750 volt system.
> They are derated 24volt stats.


 

Let's keep things in the correct scale here,  a 750 millivolt stat should never be used on a 750 volt system even if such a system exists.  The stat would be toast on first call for heat.

Funny about that derated part, since I'm finding a higher price tag on the millivolt ones than the 12 volt and 24 volt versions.

The voltage rating is for the "maximum" voltage that should go though the switch when it closes or what the anticipator's heater can handle.

There are even stats that can be used on all three normal none electric heating system control voltages. 

In the case of pellet stoves one can determine the lowest voltage rating that will work by using a volt meter and measuring the voltage across the terminals since the controller is providing the power for the circuit.


----------



## ekarlis (Feb 5, 2013)

Smokey:
    From a HVAC prospective, a 750 millivolt generator works with 750 millivolt stat. This is a 750 millivolt system&
it has been used for years on furances. Please explain to me why a millivolt generator will not work with millivolt
stat? This what I call a system. Not being sarcastic, just do not understand what you mean.


----------



## SmokeyTheBear (Feb 5, 2013)

ekarlis said:


> Smokey:
> From a HVAC prospective, a 750 millivolt generator works with 750 millivolt stat. This is a 750 millivolt system&
> it has been used for years on furances. Please explain to me why a millivolt generator will not work with millivolt
> stat? This what I call a system. Not being sarcastic, just do not understand what you mean.


 
You used both 750 millivolts and 750 volts in the same sentence that is a 3 orders of magnitude difference.


----------



## ekarlis (Feb 5, 2013)

Smokey:
      Apologies. You are right, 750 millivolt will not work on a 750 volt system. Where do you find a 750 volt system?


----------



## Thaddius Wenderoth (Feb 5, 2013)

ekarlis said:


> Smokey:
> Apologies. You are right, 750 millivolt will not work on a 750 volt system. Where do you find a 750 volt system?


 Electric public transportation vehicles use 750V. So your nearest subway or tram.


----------



## SmokeyTheBear (Feb 5, 2013)

ekarlis said:


> Smokey:
> Apologies. You are right, 750 millivolt will not work on a 750 volt system. Where do you find a 750 volt system?


 
No need for an apology at all.  

I just didn't want someone months from now scratching their heads or making assumptions.  We have enough of that on here already.  Usually it is of the my stove is so clean you can eat off of the inside of it variety.


----------



## jerjm (Nov 10, 2015)

Hi, I have been doing a lot of research to try and figure out how to use a programmable millivolt thermostat. I have a 2011 NPI 45 insert pellet stove. I got a Honeywell RTH2410B1019 stat that states it works with millivolt pellet stoves. My control panel has the transformer and two spots for wires. I got plain old themostat wire (3 wires white red and green) I have tried every combination with the thermostat and every combination with the two wires that go to the control panel and still the thermostat does not turn the unit on. It has 3 settings, Auto. Tstat and Manual. Auto and Manual work fine, I put it on Tstat with the thermostat and nothing happens. I put it on auto with the thermostat and it fires up but the thermostat is clearly not controlling the temp. I am a bit at my wits end with this thermostat thing. I just would like it to run like a normal 5, 1, 1 thermostat so that it is warm in the morning and when I come home.  Thoughts and suggestions gladly welcome!  Thanks!


----------



## Dkmcgill (Sep 20, 2019)

jerjm said:


> Hi, I have been doing a lot of research to try and figure out how to use a programmable millivolt thermostat. I have a 2011 NPI 45 insert pellet stove. I got a Honeywell RTH2410B1019 stat that states it works with millivolt pellet stoves. My control panel has the transformer and two spots for wires. I got plain old themostat wire (3 wires white red and green) I have tried every combination with the thermostat and every combination with the two wires that go to the control panel and still the thermostat does not turn the unit on. It has 3 settings, Auto. Tstat and Manual. Auto and Manual work fine, I put it on Tstat with the thermostat and nothing happens. I put it on auto with the thermostat and it fires up but the thermostat is clearly not controlling the temp. I am a bit at my wits end with this thermostat thing. I just would like it to run like a normal 5, 1, 1 thermostat so that it is warm in the morning and when I come home.  Thoughts and suggestions gladly welcome!  Thanks!


I’m in same boat. What did you figure out?


----------

