I have a Rheem gas furnace that's about 25 years old with a standing pilot gas valve. I want to replace the valve with a Honeywell spark ignition model; I can do the replace but how do I wire the control circuit for this unit? I have a camstat fan limit switch, two wired from the thermostat, a safety switch in the blower compartment and the wires from the transformer. Can anyone help me with this.



Jarell

I am rather bold with my DIY projects, but for now, I don't see a good solution to this one. The old pilot light gas valves relied on the gas to light for sure when the main valve opened. If the pilot light wasn't on, the thermocouple shut everything down.

The modern spark or hot surface furnaces rely on a flame detector and logic on the circuit board to shut the gas off if it doesn't light right away. I wouldn't want to bet my life on a circuit I made using components I selected and had no way of testing. The other thing is there is some tuning to be done to match a gas valve, the inducer if any, and the blower. It there is a good way, somebody else is going to have to explain it.

This would be a quite expensive proposition even if you can get the parts at cost. Also much wiring is needed. After all, this is a 25 year old Rheem, life expectancy of a furnace is 18-20 years. Maybe its time to change that old 70% efficient natural draft to a Rheem?Ruud modulating furnace and save hundreds of dollars annually in electricity and 25% on gas usage.