Flame controle burner

Thread Starter

Ivan Vanherpe

Joined Apr 25, 2018
I'm looking for info concerning ionisation flame controle.
Can I build a circuit that controles some relays to open valves for the gas?
I read that the probe in heating devices output some millivolts, would that be enough
to conduct a small transistor?


Joined Jan 15, 2015
Thermocouple or thermopile outputs as used for flame detection in residential furnace applications to detect flame typically output between 28 to 32 mV and no current to speak of. They can hold open the gas valves they are designed to work with but less additional circuitry for amplification they are a very small signal device. The furnaces they work with are also generally Off or ON devices using a low pressure valve and the burner ignited by a pilot flame which the thermopile or thermocouple detects. When heat is called for the pilot flame ignites a main burner when heat is called for by a thermostat. Newer residential furnaces get more complex but the older ones work pretty much as I mentioned.

The choice of gas valve you plan to use will determine the best method for control. Do you plan an ON / Off valve or a valve for flame which can be throttled? This all starts with the choice of valve, gas pressure and type of gas be it NG (Natural Gas), LPG (Liquid Propane Gas) or other gas of your choosing. Aside from using a thermocouple for flame detection, there is flame or not, there are also Flame Rods and UV (Ultra Violet) flame detection methods. All coming back to exactly what you want to accomplish.