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Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 21527
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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I have a Ruud Silhouette II gas furnace. It wont light.

Resolved Question:

I have a Ruud Silhouette II gas furnace. It won't light. The thermostat clicks on, the blower starts, a few seconds later the light begins to click. The gap is good at 1/8" and has visible spark but no ignition. Ideas?
Submitted: 7 years ago.
Category: HVAC
Expert:  Rick replied 7 years ago.
HiCustomerbr />
Is this a direct ignition unit or does it have a pilot?
Customer: replied 7 years ago.
Direct Ignition
Expert:  Rick replied 7 years ago.
You need to check the voltage to the gas valve when the ignitor is arcing. If you have ~24v at the gas valve then you have a bad gas valve. If you have no voltage then you need to backtrack from the gas valve along the circuit which typically includes rollout switches and the limit switch until you find were the voltage stops. That would be the device that is acting up. If it's a rollout switch

you can either push the button in (if it clicks you have reset it) or temporarily jump it out.
If you get no voltage all the way back to the board then you probably have a bad board.
Customer: replied 7 years ago.
I get 26-28 V at the gas valve so it must be the valve. There is no reset or anything like that I take it? get a new valve?
Expert:  Rick replied 7 years ago.
There is no reset on a gas valve. If you have 26v at the valve and no gas, no ignition then the gas valve is probably no good. I can't tell you what to do I can only advise you on what the likely problem is based on what you have told me.

Edited by Rickheatdoc on 10/10/2009 at 7:45 PM EST
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Customer: replied 7 years ago.
You were right, bad gas valve. Replaced and got heat. Thanks.
Expert:  Rick replied 7 years ago.
Thanks for using Just Answer

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