[gblackman]

I am an HVAC professional and therefore no stranger to gas controls. My oven has a low flame (verified by clocking gas meter) and often lights hard, slow to heat, slow to cook, etc. I purchased a new dual vlave (it also controls the broiler, which works fine) before removing the old valve and before I discovered that the operating voltage of the valve is apparently quite low and narrow: 3.03 to 3.30 VAC according to the tag on the valve. Replacing the valve had no effect on the problem.

Testing electrically, I find the voltage to the oven operator inadequate at 2.59 VAC and is surely the root of all my problems, but what is the cause? The schematic shows the hot surface ignitor IN SERIES (!) with the operator and thus an increase in resistance in the ignitor will increase voltage drop to the operator. I can't say that I've ever run into such a thing, but then I've never worked with a series circuit, either. The ignitor glows with the same apparent intensity as does the working broiler ignitor.

Or is the voltage output by the electronic control possibly at fault? The schematic is vague on this point, showing only 120VAC fed into the control, an internal relay, and an unknown voltage output. I know that the electronics regulate ouput to the broiler, for it accomplishes high/low operation by varying the voltage to the operator, but what about the oven ouput?

Without knowing anything about what voltages to expect, I can only guess at the fault. Can you lend a hand in diagnosis? Any help you can afford will be greatly appreciated.

[kayakcrzy]

Your oven lights hard as you would say, because the ignitor is not sending enough amps to the gas valve to open it properly. Forget all you know, and replace the ignitor. Put it all back together, and you will have it. Its too early on Monday Morning, to go into specifics. If you need me you can reach me at my website at ApplianceEducator.com Tom

[gblackman]

Tom, Thanks for the quick response. I took your advice about replacing the ignitor. Curiously enough, when I researched the part, it turned out to be interchageable with a Norton 501A, of which I had a replacement on my service truck as a furnace ignitor! Everything works fine now, voltage across the valve is now 3.6VAC, up from 2.59.

Coincidentally, I went to a service seminar on new model heating equipment yesterday. It seems that Honeywell is using this same series arrangement in their upgraded Smart Valve. We were given an acceptable resistance range with which to evaluate their ignitor, and although the instructor did not specifically say so, I'll bet we can expect to see more visually "good" ignitors failing to energize their valves as well.

Anway, thanks again for the expertise! Perhaps I can offer you the same someday!

[kayakcrzy]

I appreciate that. I have found that if the ignitor lights at all, then the circuit between the control, and the ignitor is good. The gas valve is between the control, and the ignitor. So, the furnace's should be wired the same for saftey reasons, then once that ignitor comes on, and there is no gas, that would mean the ignitor is not strong enough to open the valve. Hence you elevated voltage reading after the new ignitor was put in. Just replace it, and hit the other 9 service calls you got to do. LOL! Take Care Tom ApplianceEducator.com