Rheem Furnace problem

[Jpaullud]

Info: Rheem RGPH-07eauer- Made 1997. When I turn on the main power switch, blower motor and induction motor start immediately and continue as long as power is on, no ignition. I've replaced the board, with exact Pro Tech part. The green OK light flashes 3 times, 2 sec pause and continues doing this. This is supposed to indicate a problem with limit. All 3 limit red buttons were not tripped. Following a suggestion I jumped the red wires going to them (for test only) no change. I checked for bad fitting plugs, especially the red wires, no change. I jumped the wires to the pressure switch, no change. Any suggestions?

[LarryHome]

Ignition problems are quite common with this furnace model.

I cant speak for Rheem, however, Trane hot surface ignitors have to register between 55 and 75 ohms or else you will experience intermittent problems.

Measure your ohms and calculate your current based on the voltage applied (E=IR) and if you get less than 1 amp, you may have to replace it.

The carbide material experiences a resistance INCREASE in the material with age and the higher resistance causes less current and thus intermittent failures to ignite. Another potential issue is with fissure cracks. An otherwise good ignitor exhibiting continuity through it in a cold state will expand and cause the fissure crack to open and break the circuit - that problem will drive you nuts.

Hope that helps.

[Miller]

You should look at the idiot light code description on the furnace panel. But usually when the blower and the draft inducer take off it is a sign that there is a limit switch tripped. Check for another one down by the blower, as well as by the draft inducer, the burner box, and the back panel (usually under the burner box). Also try taking the wire off the pressure switch. Good luck.

[paul52446m]

Info: Rheem RGPH-07eauer- Made 1997. When I turn on the main power switch, blower motor and induction motor start immediately and continue as long as power is on, no ignition. I've replaced the board, with exact Pro Tech part. The green OK light flashes 3 times, 2 sec pause and continues doing this. This is supposed to indicate a problem with limit. All 3 limit red buttons were not tripped. Following a suggestion I jumped the red wires going to them (for test only) no change. I checked for bad fitting plugs, especially the red wires, no change. I jumped the wires to the pressure switch, no change. Any suggestions?

I am guessing your furnace is a down flow, so your blower is at the top of the furnace. If so take the blower door off and on the right side of the blower way back in there is a limit switch. Have you checked this limit as yet? If that limit switch is open then the blower will keep running and the burner will not try to lite. Check it out and let me know Paul