Lennox 21 pulse furnace, bad circuit board versus water drainage problem


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Old 03-20-19, 07:52 AM
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Question Lennox 21 pulse furnace, bad circuit board versus water drainage problem

My furnace was intermittent for a month and then not working. A repairman said it showed a "flame out code" and replaced the circuit board which did not correct the problem. A second repair person said condensation water was not draining and replaced clogged PVC parts and furnace then worked. Is it possible the circuit board (which I saved) did not need replacing. How would I know whether the original circuit board was actually good?
 
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Old 03-20-19, 06:04 PM
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Welcome to the forums.

Unfortunately that is considered a dinosaur in the furnace industry. Most have been removed from service due to problems. Hopefully you had yours check for heat exchanger failure.

The only way to try the board is to put it back in the furnace.
 
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Old 03-20-19, 06:20 PM
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When was the last time the heat exchanger had the Lennox pressure test performed? If not it’s time. Pulses are few and far between. Most are long gone due to heat exchanger problems.
Parts are also becoming obsolete, if they haven’t already.
 
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Old 03-21-19, 07:09 AM
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Thank you for you cautions..Pressure test on heat exchange was good. CO is also a 0 reading. For now I will continue with my pulse and continue to monitor it. Is there someone who can test the mother board...I am not prepared to put it back in the Pulse as I will count my blessings and not make any changes, leaving well enough alone. Thanks again. Hope someone will have an idea of someplace I can still have the circuit board tested.
 
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Old 03-21-19, 07:13 AM
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There’s no other way of testing it other then putting it back into the furnace.
Beyond building a test bench with a 24V transformer.
There is nowhere I’ve ever heard of that tests boards.
If your concerned, call the company and have a chat with the service manager.
 
 

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