Gas and Oil Home Heating Furnaces - How do I adjust the cycling and temperature of the furnace burners?
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toyotaguy22
12-16-08, 04:00 PM
Hello,
I have noticed that when my PG&E gas lennox furnace is running the burners are cycling on and off.
When they cycle off they stay off so long that cold air is coming out of the vents. Then I can hear the burners light up and in a little while I can feel warm air again. I never get hot air only warm air.
I think that there is some adjustment that is just not correct here.
The Lennox is about 20 years old and has been retrofit with a Robertshaw electronic ignition conversion kit with module # s8610u.
Thank you!
I have noticed that when my PG&E gas lennox furnace is running the burners are cycling on and off.
When they cycle off they stay off so long that cold air is coming out of the vents. Then I can hear the burners light up and in a little while I can feel warm air again. I never get hot air only warm air.
I think that there is some adjustment that is just not correct here.
The Lennox is about 20 years old and has been retrofit with a Robertshaw electronic ignition conversion kit with module # s8610u.
Thank you!
ecman51`
12-16-08, 04:55 PM
Test to see if your 24 volt signal, leaving your stat quits. You can more easily find out if the power at the "W" low volt terminal in the furnace where the stat wires hook up, loses it's 24 volt signal between it and any metal ground on furnace
If that is NOT the case, see if you do not have a flame sensor in the burners area, that needs taken out and polishing up? If I were you, I would access the big furnace panel and actually watch and see how long your have flame. If it goes out in about 4 seconds, it's almost certainly the flame sensor issue. If it lasts longer or much longer than that, it may be the other issues.
Or if this furnace has a pressure switch, you should test to see if the outgoing wire from that pressure switch shuts down, which may indicate something like backed up condensate, where you would need to blow out the condensate hose and it's trap, as this back up into the secondary exchanger can shut down the pressure switch.
Or make sure furnace is not high limiting. Like the pressure switch outgoing wire test, you would likewise see if you lose power in the wire leaving the limit switch.
A module could be suspect after other things check out good.
This is a good start.
If that is NOT the case, see if you do not have a flame sensor in the burners area, that needs taken out and polishing up? If I were you, I would access the big furnace panel and actually watch and see how long your have flame. If it goes out in about 4 seconds, it's almost certainly the flame sensor issue. If it lasts longer or much longer than that, it may be the other issues.
Or if this furnace has a pressure switch, you should test to see if the outgoing wire from that pressure switch shuts down, which may indicate something like backed up condensate, where you would need to blow out the condensate hose and it's trap, as this back up into the secondary exchanger can shut down the pressure switch.
Or make sure furnace is not high limiting. Like the pressure switch outgoing wire test, you would likewise see if you lose power in the wire leaving the limit switch.
A module could be suspect after other things check out good.
This is a good start.