Greenhouse thermostat help…

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I have a 12’x 30’ GH, freestanding about 35 yards from my house. It has its own electricity and propane. 2 heaters that do a great job. A Modine “Hot Dawg” heater and a Williams 30,000 btu heater that will function if electricity goes out.
The Williams Heater does an excellent job, but the millivolt thermostat has already quit or “stuck” in the off position. I believe because of humidity… I turned it off, cycled it and it started working again. Murphy’s Law says it will do it again…I WILL replace it.
But with what??
It makes no since to put the thermostats in my house. Lines will have to be buried and house is on a concrete pad. Commercial greenhouses have generators and use a thermostat requiring power.
My question to Slippertalk Greenhouse owners,”What millivolt thermostat are you using”!
Thank you for your replies in advance and I appreciate your help. Duck
 

Ray

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The "millivolt" specification merely means that is as much juice as it is capable of carrying. A "line voltage" thermostat has more capacity, but still can be used on your heater, as it's merely looking for an on/off function.

I upgraded to one of these on that same heater a long time ago, and it worked fine for decades.
 

Ray

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Now you have me wondering if I gave you incorrect advice! Apparently, I confused “low voltage” with “millivolts”

My experience with thermostats is that they are nothing more than temperature-controlled switches. If they are not connected to anything (i.e., no electricity passing through them) they will still open and close the contacts in response to the temperature, and the voltage rating is merely a specification of how much they can handle.

A thermostat is simply a switch that closes and completes an electrical circuit once a temperature setpoint is reached.

Apparently however, millivolt thermostats use a thermopile exposed to a pilot flame to generate a small DC voltage. I have never seen one of those and my Williams heater did not use one of those. Looking at the owners manual, it does not appear that’s what it is, anyway. Why don’t you give the manufacturer a call (888-444-1212) and get clarification.
 
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Thank you Ray!
Since it isn’t wired to any electricity and the heater isn’t either. What thermostats do other greenhouse owners use?? The millivolt thermostat that comes with the heater is an inexpensive LED model…surely I am not the only ST person that has been down this road before?
 

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