the Egg Man
Nov 13, 2006, 09:51 AM
I have a 30+ year old forced air furnace. Currently, when the thermostat is turned up to call for more heat, the burners ignite normally. When the heat exchanger-HE- gets to temperature (which seems to take a long time) the fan switches on normally.
HERE'S WHRE THE PROBLEM STARTS
The fan runs for approx. 1-2 minutes and shuts off. It repeats this continually, over and over. The burner does not shut down.
I believe the burner doesn't shut off because the thermostat is still calling for heat.
I also believe with all the on/off/on/off at some point the breaker trips. Regardless, I have shut the furnace down before it can complete enough fan cycles to heat the house completely to the temperature the thermostat is calling for.
Right now the fan limit switch has 3 temperature indicators settings visible.
Let me describe:
1. it is a round silver (tin) disc with a temp. range at the bottom.
2. the three settings from low to high are 80F. 130F. and 205F.
My guess is 205F. is the HE limit. the the low limit is 80F. and the high limit is 130F.
What are the correct temperature settings for a fan limit switch. From low to high
(keeping it as simple as possible)
Thank you,
Look forward to your answer, Egg
Answers to your standard questions:
Manufacturer:
SUNBEAM
Model number may or may not be helpful.
Age of equipment:
30+
Efficiency: Natural draft, 90%, 80%.
NATURAL DRAFT (PIPE TO CHIMNEY)
Plastic flue pipes are 90% Metal flue pipe and a draft inducer blower are 80% metal flues with no
Draft inducer fan are natural draft.
Type of system:
Heat pump, hot water, forced air, etc.
FORCED AIR
Type of fuel:
LP, NG, oil.
NG
Tell us:
Does anything start. Any noises or blowers run when you turn it on?
DESCRIBED ABOVE
Try to turn fornace off and on at power switch or breaker.
Did this do anything?
YES. IT TURNS IT OFF AND ON NORMALLY
Modern furnaces will lock out, either what's called a soft lock out or hard lock out, if it detects a problem 3 times.
I hope this will help speed up the process of you getting a faster more accurate response.
HERE'S WHRE THE PROBLEM STARTS
The fan runs for approx. 1-2 minutes and shuts off. It repeats this continually, over and over. The burner does not shut down.
I believe the burner doesn't shut off because the thermostat is still calling for heat.
I also believe with all the on/off/on/off at some point the breaker trips. Regardless, I have shut the furnace down before it can complete enough fan cycles to heat the house completely to the temperature the thermostat is calling for.
Right now the fan limit switch has 3 temperature indicators settings visible.
Let me describe:
1. it is a round silver (tin) disc with a temp. range at the bottom.
2. the three settings from low to high are 80F. 130F. and 205F.
My guess is 205F. is the HE limit. the the low limit is 80F. and the high limit is 130F.
What are the correct temperature settings for a fan limit switch. From low to high
(keeping it as simple as possible)
Thank you,
Look forward to your answer, Egg
Answers to your standard questions:
Manufacturer:
SUNBEAM
Model number may or may not be helpful.
Age of equipment:
30+
Efficiency: Natural draft, 90%, 80%.
NATURAL DRAFT (PIPE TO CHIMNEY)
Plastic flue pipes are 90% Metal flue pipe and a draft inducer blower are 80% metal flues with no
Draft inducer fan are natural draft.
Type of system:
Heat pump, hot water, forced air, etc.
FORCED AIR
Type of fuel:
LP, NG, oil.
NG
Tell us:
Does anything start. Any noises or blowers run when you turn it on?
DESCRIBED ABOVE
Try to turn fornace off and on at power switch or breaker.
Did this do anything?
YES. IT TURNS IT OFF AND ON NORMALLY
Modern furnaces will lock out, either what's called a soft lock out or hard lock out, if it detects a problem 3 times.
I hope this will help speed up the process of you getting a faster more accurate response.