Help: Lennox G8 no heat

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Old 12-05-08, 04:04 PM
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Help: Lennox G8 no heat

I got a Lennox G8 gas furnace. I just noticed I got no heat. The pilot is on, but when I turn up the temperature, the fan is on but there is no fire (there is a hum noise as it was trying but no flame). When I was looking, I touched one of the copper coil (thermocouple) beside the pilot, the fire went on for a few seconds and then went out again.

Please let me know what may be the problem. Any help would be appreciated. Thanks in Advance.

PS. I just recently installed a AC, and had relay switch installed. I remember the furnace was working when they installed it.
 

Last edited by homedoit; 12-05-08 at 04:58 PM.
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Old 12-05-08, 08:11 PM
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additional info, the voltage to the gas valve is only 15 volt. Is this normal? I have two furnace, the one works has 24 volt (a slightly bigger furnace).
 
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Old 12-05-08, 08:19 PM
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Originally Posted by homedoit View Post
additional info, the voltage to the gas valve is only 15 volt. Is this normal? I have two furnace, the one works has 24 volt (a slightly bigger furnace).
No it is not normal. try disconnecting the thermostat and jumping the red and white wires. I have had electronc thermostats that would do exactly as you have explained.
 
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Old 12-05-08, 08:56 PM
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Originally Posted by mbk3 View Post
No it is not normal. try disconnecting the thermostat and jumping the red and white wires. I have had electronc thermostats that would do exactly as you have explained.
Thanks. The same result. The red wire and ground was 24 volt, as soon jump the two wires (Red and white), the voltage drops to 15 volt.

Any suggestions? Thanks
 
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Old 12-05-08, 09:10 PM
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Well, try examining the neutral wire inside the furnace make up box and at the wall. A poor neutral will give goofy reads
 
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Old 12-05-08, 09:59 PM
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Originally Posted by mbk3 View Post
Well, try examining the neutral wire inside the furnace make up box and at the wall. A poor neutral will give goofy reads
The AC guy installed a new relay switch, i noticed there a green wire coming out of it has nothing connected to but a cap (the one normally used to screw two wire together).

What is the relay switch for? Can I by pass it? Would adjust the pressure do anything?
 
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Old 12-06-08, 07:51 PM
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Why don't you call the a/c installer back
 
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Old 12-08-08, 09:36 AM
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Originally Posted by mbk3 View Post
Why don't you call the a/c installer back
I made a mistake to have direct energy to install the unit. They tell me they have 30 day warranty on installation. They'd charge me $100 to come out and fix it.

The guys from Direct Energy are not very good, I had a lot of problem figuring out the wiring when they installed the A/C. If I need to pay, I want to find a good company.
 
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Old 12-10-08, 01:45 PM
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Originally Posted by homedoit View Post
I made a mistake to have direct energy to install the unit. They tell me they have 30 day warranty on installation. They'd charge me $100 to come out and fix it.

The guys from Direct Energy are not very good, I had a lot of problem figuring out the wiring when they installed the A/C. If I need to pay, I want to find a good company.
Just want to follow it up. I called a different lady at direct energy, she is good and we agreed that I'd pay if only it is a problem from the furnace. The tech guy found a faulty control circuitry that fried the transformer and gas valve. I am happy that they fixed it without a charge. This tech guy was also much more knowledgeable than the A/C fellow and he programmed the controller correctly (it was incorrectly set for a electric furnace instead of gas).

Also I measured the power on the gas valve, It used to be no power to it unless the unit is on. The new wiring the power is there all the time which is the same as my other furnace. So they must somehow miswired it when they installed the A/C.
 

Last edited by homedoit; 12-10-08 at 02:15 PM.
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