Professional Member
I have a commercial building with 4 Goodman Furnaces and 2 of them are not able to close the pressure switch that comes of the condensate collector on the secondary heat exchanger. I cleaned all the lines--no pluggs but still is measuring below the vacuum needed to close the switch.
Can this be anything other then a plugged exchanger??
Professional Member*
If it's reading differential pressure do you have the correct differential between the high and low side? Have you checked the flue and intake for obstructions? If you put a manometer on it and it's with in range and still not closing the switch then you have a bad switch.
Professional Member
Vents were checked an well with in the lengths. I did check with a manometer and I am right at the the limit of-.4 which is the rating on the switch.
God Speed, Jim. We'll miss you - 2-26-23
Check the heat exchangers.
Banned
Check the inducer squirrel cage wheel.
Regular Guest
the rating on the switch is the point it reopens not the point it closes. you do not have enough vacuum. have you ensured that the inducer assembly is clear? are the ports to the pressure switch clear of debris? I did not see an answer if the venting was inspected for clogs, bugs, standing water, etc. just a statement that the length was correct. how long are the venting runs? what size is the vent pipe? how many 45s and 90s on vent and intake. what is the model of the furnaces?
Professional Member
Pull the inducer to inspect it and take a look at the secondary heat exchanger.
Professional Member*
Just had one, that I found a wasps nest about the size of a silver dollar. Wasn't dropping out on low vacuum, but tripping out on the flue temp sensor.
It doesn't take much, to obstruct the air flow.
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Are they all the same model?Originally Posted by bow hunter
To second what "JmanHVAC" said - what is the model number of these units?
Instead of learning the tricks of the trade, learn the trade.
Regular Guest
I just had a unit with the same issue. I pulled the inducer assembly to check the secondary and a dead mouse fell out of the inducer wheel, problem solved
Regular Guest
where did OP go? We would love to know what was found as the problem.
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