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Discussion Starter · #1 ·
Hello All,
I need to hookup an old thermostat to a greenhouse Modine gas heater and I would appreciate some input. It's just a two wire t-stat hookup off an old manual coil type t-stat. I'm assuming the two t-stat wires need to go to "R" and "W" on the circuit board.
But do I also need to install a jumper between "W" and "G"? Because the diagram seems to suggest that I do. Otherwise, will the blower come on automatically with a call for heat? Typically the blower comes on prior to the furnace firing up and then stays on for a short period after the furnace goes off, to cool the unit.

I'm still trying to hookup everything, so I wanted to confirm the above prior to firing it up.

Thanks,
Ralph
 

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Your wall thermostat that you are not showing, will send 24 Volt on the W Furnace thermostat. At same time it will send 24 Volt on G to turn on fan. Both of those get they common (natural all the time.

Connecting permanent 24 Volt from R to W or G will just make them run all the time disregarding the temperature setting.
 

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Discussion Starter · #8 ·
Hello and thanks for the input. Yes, I think I do recall reading that the "G" is for a three wire t-stat hookup where you desire the ability to run the fan alone. So I should only have to connect to the "R" and "W" which is what I thought. Thanks for confirming that Tinkerman and Supers05. So a call for Heat should tell the fan to run.

Runagate, the last pic is of our t-stat. I'm not overly familiar with these types but it is manual only. There is no power on it. The coil apparently expands and contracts which in turn opens and closes an internal switch. That in turn either opens or closes the circuit.

Ralph
 

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Hello and thanks for the input. Yes, I think I do recall reading that the "G" is for a three wire t-stat hookup where you desire the ability to run the fan alone. So I should only have to connect to the "R" and "W" which is what I thought. Thanks for confirming that Tinkerman and Supers05. So a call for Heat should tell the fan to run.

Runagate, the last pic is of our t-stat. I'm not overly familiar with these types but it is manual only. There is no power on it. The coil apparently expands and contracts which in turn opens and closes an internal switch. That in turn either opens or closes the circuit.

Ralph
Some confusion here. The t-stat you are showing is for heating only (heater temperature). That is not your main t-stat that controls it all, including cooling. Something like Nest, or Honeywell make.
 

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Some confusion here. The t-stat you are showing is for heating only (heater temperature). That is not your main t-stat that controls it all, including cooling. Something like Nest, or Honeywell make.
No, not even a bit correct.
I don’t know what your purpose is here but constantly giving inaccurate information to folks needing help is doing a huge disservice to the site and causing embarrassment to yourself.
 

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Discussion Starter · #12 ·
UPDATE:

So I was able to finish hooking up two of the heaters and they worked perfectly. The exhaust fan, blower fan and igniter are all working as it is supposed to. When a call for heat is initiated from the t-stat, the exhaust and blower fans do come on automatically. So thanks for confirming that I only needed to use "R" and "W" on the circuit board. The "G" is indeed only meant to be used in case you desire to run the fan alone. I wanted to confirm that because the hookup for the heaters that were replaced, which were very old, was quite different. Whereas the hookup on these new heaters with the circuit boards turned out to be very simple.

Thanks again,
Ralph
 

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Some confusion here. The t-stat you are showing is for heating only (heater temperature). That is not your main t-stat that controls it all, including cooling. Something like Nest, or Honeywell make.
It's a modine gas heater all it does is heat. The only tstat you need is heat only. You obviously have no clue what your talking about. If you actually knew the equipment that is being talked about you'd see what a fool you are.

Sent from my SM-N975U using Tapatalk
 

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It's a modine gas heater all it does is heat. The only tstat you need is heat only. You obviously have no clue what your talking about. If you actually knew the equipment that is being talked about you'd see what a fool you are.

Sent from my SM-N975U using Tapatalk
Gotta remember, this is the one offering cap advice but didn’t know what herm was
 
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