Spark but no flame - HELP!

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Old 02-28-11, 04:42 AM
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Spark but no flame - HELP!

I have a Rheem Imperial 80 furnace that is refusing to light this morning. When the t-stat calls for heat, the ignitor sparks, but the pilot will not light. I cycled the power to the furnace to get it to try to light again and this time I put a lit grill lighter on the pilot while the sparks were going - the pilot still would not light.

I replaced the control module a couple years back so I'm thinking this is the gas valve. That valve is a Robertshaw Grayson 7100 DER-S7C.

If it is the valve, is there any special considerations before replacing it?

Thanks.
 
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Old 02-28-11, 05:34 AM
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ensure your gas meter has not been pinned.
check for 24V @ gas valve while unit is sparking
 

Last edited by hvactechfw; 02-28-11 at 06:22 AM.
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Old 02-28-11, 05:45 AM
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Not sure what "pinned" means, but there is 25.37 volts between the P and C wires when the unit is sparking, This spark lights a pilot, which heats up a thermocouple. After that thermocouple senses heat, it sends a signal back, allowing the gas valve to open.

The problem is that I don't have any gas coming out of the pilot.
 
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Old 02-28-11, 05:55 AM
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Pinned is the pinning of your gas meter, where your gas company shuts off your gas.
Do you have other gas appliances? Do they work?
what is the serial number of your furnace?

You have the correct voltage, now we must ensure you have gas to the unit.
 

Last edited by hvactechfw; 02-28-11 at 06:16 AM.
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Old 02-28-11, 06:10 AM
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Yes, I should have mentioned before that I checked our gas stove and the gas is on. I should be back to the house in a few minutes, I will post the serial number ASAP.
 
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Old 02-28-11, 10:13 AM
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Also make sure that the gas hasn't been shut off at the electric gas valve, which probably has an "on" position, and that the furnace shutoff valve is on.


If that's the case, the pilot light may be plugged up, preventing gas from flowing. Loosen the brass ferrule compression fitting that holds the pilot tubing in the gas valve and see if you have gas coming out when you have the furnace switched on as you describe.
 
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Old 02-28-11, 11:16 AM
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Thanks everyone. It turned out to be a plugged orifice as SeattlePioneer suggested. However, I did stop by a local HVAC place and they told me these furnaces had been recalled in the late 90's and they were installing them then for free. I asked about now and all they said was that maybe Rheem would give me $100 off. Wow thanks.

I did invite them to come over and take a look at my heat exchanger and to clean the furnace. They made it sound like there was potential for me to kill my whole family with this furnace. I have a CO detector and it has never gone off, so I am dubious about that claim.

Thoughts?
 
 

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