Originally Posted by Tator1076
Check the fan limit. Also check if the bar fitting from pressure switch to draft motor is clear.
There are no fan limit switches, two manual reset overtemp sensors on the fan cage, one either side. Neither one trips. Since they are in series with 3 other heat limit sensors, they are not likely the cause, but I will recheck for loose wiring.
Fan is timed for 150 second run after the burner stops. It is not controlled by a low temp sensor.
Will check hose fittings again, but I was able to blow through all hoses easily. Thanks for your ideas.]
Bill. PS Konked out again this PM. Even changed the batteries at the
Aprilaire thermostat out of frustration.