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Hi, how are you? Is there a circuit board in the blower compartment of the furnace? Thanks
You mean as soon as the main blower starts up?
Do you see the flames blow out any at all before the pressure switch error occurs and the furnace shuts down? Like do you see the flame pattern change?
Alright, is it tripping an error when the inducer shuts off without firing the furnace?
That's unusual. With no error code?
Is the draft inducer hot to the touch?
Flame pattern looks normal?
Usually they will run longer than five seconds before tripping the error. Check the tubing running to the switch for clogs and such. Also check the connections the tube attaches to.
Then I would replace the pressure switch, but I find it odd for it to act up when the blower starts up. The blower should not affect the function of the pressure switch. That makes me suspect a leakage in the heat exchanger, but your described flame pattern disagrees with that too.
Often the labels will tell the amount of vacuum it should be. The labels on the switch. Seems the switch is defective. No change in operation now even when the blower is running?
You have a reading of 1.5" positive pressure?
You would need at least .5" to trip the switch. So I would suspect a damaged draft inducer wheel, a clogged flue pipe, or a crack in the heat exchanger.
Disconnect the pressure switch tubing from the switch and hook that up to your manometer and tell me what the reading is. Just jump the switch to get it to run long enough to get a stable reading.
That's too high. Either theres a blockage in the exhaust vent, there is a leakage in the system on the vacuum side such as the housing or heat exchanger, or there is an issue with the blower wheel.
Do you have carbon monoxide detectors in your home?
Yes, I think you will be fine. I just would make sure they are working so that we know you will be safe. My biggest fear would be if there is a small crack in the heat exchanger and flue gas leaking into the home.
Birds. Ice or snow if there is a lot of drift in your area.
Oh well if it feels good outside then I doubt theres a restriction in the pipe itself.
Maybe the wheel is missing a few teeth and it is just enough to prevent it from pulling the vacuum. does the wheel sound like it is imbalanced when it starts up?
You can always pull the housing and inspect it. When you put it back on, use high temp silicone and just run a good bead around the housing where the gasket is. Works great to reseal it.
Please keep me updated with what you find. Do you have any other questions?
Is this a 90% furnace or an 80%?
Must be a 90%. I never asked. One more idea. Check all of your drains and make sure the furnace is draining properly. I apologize for not asking before now. That was an oversight.
If you have a PVC flue pipe it is. There is no reason to reduce the exhaust vent. If it is 2" that is fine. Check all of your drains. Make sure the draft inducer isn't holding water. Which would also explain the pressure switch issues.
Is there any kind of gurgling when the draft inducer starts up?
Remove the drain trap if you can from the furnace, have a bucket ready and see if you get any water flow out of it. You may have a clog in the trap, or the pipe that runs from the trap to the condensate pump.
Let me know what you find out with the drain.
Ah, I see.
Then I would continue with the plan to pull and inspect the draft inducer.
Alright, keep me updated. Thanks