the fenwal (ingntion control) sounds interesting.
the blower seems to be totally fine and the exhaust it unobstructed. It reads about ambient temp when I test it, which seems right, as the heater doesn’t stay on very long.
Sta Rite sr200 lights and runs then stops
- Thread starter Turbosnow
- Start date
the fenwal (ingntion control) sounds interesting.
the blower seems to be totally fine and the exhaust it unobstructed. It reads about ambient temp when I test it, which seems right, as the heater doesn’t stay on very long.
It might be a failing air flow switch or maybe the circuit board is going bad.
Do you feel like the blower is working correctly?
Have you verified that there's good airflow coming out of the vent where the exhaust exits the building?
Do you feel like the blower is working correctly?
Have you verified that there's good airflow coming out of the vent where the exhaust exits the building?
Disconnect the wires from the air flow switch and check the resistance of the switch at the terminals. It should be OL (Open Line or Over Limit) before the blower comes on.
Start the heater with the wires disconnected and watch the resistance of the switch. It should go to zero ohms as soon as the blower starts. It shouldn't try to fire since it won't get a good signal from the airflow switch. Turn off the gas just to be safe.
You could connect the AFS wires together to make the heater run by simulating a closed air flow switch, but I would not do that in this case since it's indoors and we don't know if there is an air flow issue that could be potentially dangerous.
You could connect the wires together with the gas valve shut off so that the heater won't actually fire.
The blower will start and run, the heater will try to fire, but it won't since there's no gas and the heater will shut down after a few seconds when it doesn't get flame rectification. However, that will give us enough time to see what happens.
If the AFS blinks with the wires connected together, then the board is bad.
Also, watch the resistance of the air flow switch while the blower is running. It should be a steady 0 ohms. If it's fluctuating, the switch is bad or you have some sort of actual airflow problem.
Start the heater with the wires disconnected and watch the resistance of the switch. It should go to zero ohms as soon as the blower starts. It shouldn't try to fire since it won't get a good signal from the airflow switch. Turn off the gas just to be safe.
You could connect the AFS wires together to make the heater run by simulating a closed air flow switch, but I would not do that in this case since it's indoors and we don't know if there is an air flow issue that could be potentially dangerous.
You could connect the wires together with the gas valve shut off so that the heater won't actually fire.
The blower will start and run, the heater will try to fire, but it won't since there's no gas and the heater will shut down after a few seconds when it doesn't get flame rectification. However, that will give us enough time to see what happens.
If the AFS blinks with the wires connected together, then the board is bad.
Also, watch the resistance of the air flow switch while the blower is running. It should be a steady 0 ohms. If it's fluctuating, the switch is bad or you have some sort of actual airflow problem.
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Here you're saying that the blower is running slow?
Do you think that the blower is running correctly or do you think that it has a problem?
With the afs switch connected it sounds like the blower is working just fine. When I disconnect it and jump the two wires together that go to the switch the blower runs slow and the heater does not ignite. This is pretty strange I think, and would seem to indicate some sort of logic error. I’ll jump them and make a video.
I tested the am resistance across the afs and I think that the thing might be shot. It is mostly around 1.6 ohm but then varies like crazy up and down. It never hits zero.
You might have a bad AFS but it might be an actual airflow problem.
If the AFS wires are connected before the blower starts, the circuit board might determine that the AFS is bad because the AFS should not show as closed until the blower starts.
It's expecting open until the blower starts and then closed.
You can try waiting until the blower starts to connect the wires to see if that makes any difference. Do this with the gas valve closed so that the heater won't actually fire.
You might have a failing blower or maybe a problem with the venting.
Since the heater is old and indoors, you should have it serviced by a qualified gas contractor to make sure that everything is working correctly and safe.
If the AFS wires are connected before the blower starts, the circuit board might determine that the AFS is bad because the AFS should not show as closed until the blower starts.
It's expecting open until the blower starts and then closed.
You can try waiting until the blower starts to connect the wires to see if that makes any difference. Do this with the gas valve closed so that the heater won't actually fire.
You might have a failing blower or maybe a problem with the venting.
Since the heater is old and indoors, you should have it serviced by a qualified gas contractor to make sure that everything is working correctly and safe.
I think that the heater is super old.
If you have a digital differential pressure manometer, you can check the actual pressure differential.
I think that the pressure differential should be greater than 1.25" w.c to close the pressure switch.
If the pressure differential is more than 1.25" with the blower on, then I would replace the AFS.
If the pressure differential is less, that points to an airflow problem.
Airflow problems can be blower related or power related or maybe a blockage in the airflow path such as a sooted exchanger or something in the vent pipe.
If you have a digital differential pressure manometer, you can check the actual pressure differential.
I think that the pressure differential should be greater than 1.25" w.c to close the pressure switch.
If the pressure differential is more than 1.25" with the blower on, then I would replace the AFS.
If the pressure differential is less, that points to an airflow problem.
Airflow problems can be blower related or power related or maybe a blockage in the airflow path such as a sooted exchanger or something in the vent pipe.
I don’t have a pressure differential switch unfortunately. I ordered a new afs to see if that is the issue. The heater is old but it wasn’t used for at least 7 years so it may have low ish hours on it.
it could be soot in the heat exchanger,but the exhaust is unobstructed.
it could be soot in the heat exchanger,but the exhaust is unobstructed.