Tempstar gas furnace
#1
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Tempstar gas furnace
I have a tempstar gas furnace that is around 12 years old. When I turn the thermostat up in the morning the frunace will light but then the burner will go out it will relite but then will go out again I can here the spark and also the burners light but it will keep this up until the house reaches temp. Any ideas?
#2
Does the sparking stop once the burners light-up? or do the burners perhaps light-up for just a few seconds with the sparking never stopping at all until the burners shut down completely?
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The spark stops when the burner lites, they stay lit for a few seconds then shut off, then
the spark lites them again. you can here the spark lite the burners then a click and the burners go out as soon as they go out the spark relites them and the process starts again.
the spark lites them again. you can here the spark lite the burners then a click and the burners go out as soon as they go out the spark relites them and the process starts again.
#4
The Tempstar furnaces I'm familiar with used a Honeywell ignition module to light a pilot light, which in turn lit the main burners after the pilot lit.
But what you describe seems to be a direct spark ignition system that lights the main burners directly.
What is the make and model of the ignition control box on the furnace?
But what you describe seems to be a direct spark ignition system that lights the main burners directly.
What is the make and model of the ignition control box on the furnace?
#5
I'm with SP. The tempstar furnaces I'm familiar with that used spark ignition used an intermittent spark ignition module to light a pilot which then lit the main burners. It sounds as though you may have poor flame signal or a weak pilot if your furnace uses this type of setup. Please answer SP's question of the make and model of the ignition control box.
#8
Get the heat exchanger checked.
Don't pull the pilot assembly unless you really know what you're doing; it's easy to cause a gas leak, kink the aluminum tube, or damage the gas valve.
Don't pull the pilot assembly unless you really know what you're doing; it's easy to cause a gas leak, kink the aluminum tube, or damage the gas valve.
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I pulled the pilot lite assy last night,cleaned it and reinstalled it and it did not help. I know the furnace is old but it has no other problems and I just want to get it through this season and then I will purchase a new one this summer. I have had it checked for carbon monoxide and it passed with no problem. I watched it last night and this is what happens. When you turn it on and the thermostat calls for heat the small fan come on and runs for about 1 min then the spark lites the pilot and the burners light, they burn for about 1 min and then go out, then the spark lites the pilot again and the burners lite again run for about 30 sec. and go out, this goes on until the house reaches temp but every time it cycles the burners stay lit a little longer. Is there a thermal switch that turns the gas off if it does not sense a certain temp??
#10
Probably some control is shutting off the burners. You need to trace out the low voltage 24 VAC circuit that goes from the R to the W terminal, to the pressure switch and limit switch, to power the ignition control module. Probably something is shutting off the furnace along that circuit.
Do you have multuimeter that measures AC voltage and understand how to use it? You need to identify where that 24 VAC is being shut off along that circuit.
Do you have multuimeter that measures AC voltage and understand how to use it? You need to identify where that 24 VAC is being shut off along that circuit.
#11
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You should mention things you ruled out.
Things to rule out: The chimney might be partially blocked by debris causing exhaust to trigger the heat sensor which shuts the furnace off as soon as it heats up. If the blower wheel is fowled it will no longer push the air, which means it will spin too fast and not cool the overheating the motor. A heat sensor shuts the motor off. On my furnace it only took a few minutes for the motor to overheat.
Things to rule out: The chimney might be partially blocked by debris causing exhaust to trigger the heat sensor which shuts the furnace off as soon as it heats up. If the blower wheel is fowled it will no longer push the air, which means it will spin too fast and not cool the overheating the motor. A heat sensor shuts the motor off. On my furnace it only took a few minutes for the motor to overheat.