They placed a thermocouple under the pilot flame, and as long as it was lit it generated voltages, in the millivolt range, that held a small solenoid open in the burner control assembly, allowing gas to flow to the burners, if heat was called for. If the pilot went out for some reason, the thermocouple stopped generating voltage and the solenoid closed off the gas to the whole system.

I have that system. It works because the electromagnet coil is just a few turns of thick copper wire. The few mV from the thermocouple can thus drive an Amp or so through the coil.

 

I would just add a second thermocouple use it to turn on a npn and let that turn on a MOSFET that could switch a relay.

 

I can say for a fact there is no power source connected to the system.

OK. I've been wrong before. And I certainly don't know everything. I only know what I know. I just can't help but not know what I don't know.

My apologies TonyR, I did not mean to reply with that whole explanation of how a gas furnace works, obviously you already knew that. I tried to edit my reply but for some reason it would not let me

No need for an apology. I've been spoken at by people who MEANT to be rude. I didn't take your reply as being rude. Good luck with your project.

 

I believe it’s powered by a turbine driven by the pilot flame flow, but that’s little more than a guess.

I knew I should not have written that. The installer told me that, and I guess that's why he installs heaters for a living. I'm sure my system uses the very common thermopile solution.

 

Why not use the contacts on the thermostat to control two relays. The contacts on a small relay could connect to the wires that originally connected to the thermostat contacts. The larger relay would control the power to the blower. You would need to look at the contact rating of the relay in the thermostat receiver unit to make sure they could handle the current for the new relay coils.

Les.

 

Why not use the contacts on the thermostat to control two relays. The contacts on a small relay could connect to the wires that originally connected to the thermostat contacts.

Original post states that it's a non-wired system. No wires other than the pilot light thermocouple to the gas valve. The rest is radio controlled (I think).

 

the natural gas burner is controlled by a remote thermostat. It has a remote transmitter that you can set to particular temperature and a receiver box that connects to the gas valve to turn it on and off

That receiver is going to need power. Be it from a transformer or from batteries. That's where you're going to gain control for a fan. GOTTA be wired somehow.

Can you take pictures? For me?

 

That receiver is going to need power. Be it from a transformer or from batteries. That's where you're going to gain control for a fan. GOTTA be wired somehow.

I agree. There has to be a set of contacts that close in order to activate the gas valve which can be used to trigger a DPST relay, that gets it's power from the power source that runs the fan, to turn the fan motor and the gas valve at the same time.

I say that's a totally reasonable solution to the issue.

 

there MAY be an auxiliary manual valve. (POST #10)

My mother-in-law had a fireplace with an electronic controlled gas valve. Just flip the switch on the wall and it was on. Pilot continued to burn day and night, and in the summer time we'd put it out. But in the case of a power failure there was a hand turned valve that would open the gas valve and the fireplace would come on. Hers was equipped with a fan upgrade possibility. She never put a fan on hers, but it was "Fan Ready" That's why I'd really like to see some pictures of your gas valve set up.

 

In post #1 the TS seems to suggest that the receiver unit is separate from the heater and just presents a set of contacts to the input of the control board so that it just imitates a normal hard wired thermostat. The has been no mention of how the receiver unit is powered. We need clarification from the TS.

Les.

 

We haven't heard from the TS (Eclipse06) since Saturday. 5 days ago. I think he's become frustrated with us and has abandoned his desire to find a solution to his goal. Otherwise by now he should have responded and given us the details we need in order to understand exactly what he's working with.

@Eclipse06 We are a bunch of people who love to solve problems. If we can teach something here then we feel useful. At least I can say that is true of myself, I can't really say that for others, but I suspect that's somewhat true to some degree, greater or lesser than myself. If I knew how your unit functioned then perhaps I could come up with a solution to help you reach your goal. Unless we hear from you I think we're going to start dropping off from this thread. Please don't give up on this project. It's quite likely an easy solution. As long as we know what we're working with.