Electronic ignition system for burner

I haven't read about very many people taking this approach for a HERMS system so I'm looking for clarification to see if I've got the concept correct (and I'm not going to suck down CO or blow myself up).

I plan on using high pressure propane with an adjustable regulator. I'd like to use an outdoor grill's electronic ignition system to light my burners (Something like this kit) without a pilot light. If the ignition system does not come with a flame sensor, I'd pick that up separately.

I'll have a computer controller managing the logic, eg, if the gas solenoid is open but the flame sensor reads false then close the solenoid, wait for gas to clear, then begin ignition cycle. The ignition cycle would consist of opening the gas solenoid, sending a signal to the electronic ignitor, and setting a timeout for the flame sensor, shutting down if lighting was unsuccessful.

My questions are: will this work? is this safe/sane? am I missing anything?

Sounds like a workable approach, the devils in the details though as the ignitor is just a spark generator no flame sensing. The current methods used are cad sulphide photo cell and rectified AC from flame touching sensing rod. If you could build a reliable photo cell and circuit to watch for flame presence it would be the simpler approach to build. To be safe the control system will have to test it for no flame condition before start up and monitor it during operation. The photo cell would have to positioned and tuned to not respond to other hot surfaces that might give false readings after burner was in operation and you had a flameout.
The rectified AC method applies a high AC voltage to the flame rod and the flame rectifys the AC and a circuit senses the current flow through the flame rod circuit.
The safer off the shelf route is to use a electric ignition module with built in safety circuits to do the job. The ability to operate and or shut down independant of the control command will be valuable if the control program hangs at the wrong moment and the flame goes out.

kladue said:

The safer off the shelf route is to use a electric ignition module with built in safety circuits to do the job. The ability to operate and or shut down independant of the control command will be valuable if the control program hangs at the wrong moment and the flame goes out.

Click to expand...

I'd definitely go with a manual shutdown switch for the solenoid (as well as a needle valve between the solenoid and the burner) in case anything goes amiss.

Your response is very much appreciated! I was thinking of a simple bi-metal flame sensor with the probe mounted in the flame, like these furnace flame sensors. Is that approach going to suffice or should I look more towards the photo cell or optical sensors?

The flame sensors in the link are just SS probes with a porcelan insulator, they do not generate any current or voltage potential. The thermocouple flame sensors and power units have a long response time so unsafe amounts of gas can flow before there is a signal change. The challenge with a photo cell is the low level of light emitted from a gas flame, a cell that responds to ultraviolet light from the flame would be the best choice for a flame detector.

Ah, thanks for the clarification and saving me from some potential headaches (literally). I'm off to look further into photocell and UV sensors.