Strong, gusty 45mph winds typical for Fall here have been messing with induced draft blower vacuum signal to the pressure switch, especially the cyclonic nature of said winds this year.
Shuts the furnace down prematurely when alternating positive/negative pressure waves in the flue mess with the blower vacuum signal to pressure switch pintle from gusts blasting across the furnace exhaust flue outlet above the roofline. Pressure switch tests prove no diaphram rupture, microswitch function ok. Flue terminates approximately 22 feet above the ground, through the garage roof, along the split level exterior wall, through the adjacent eave of the attached main house terminating about 3 feet above the roofline with a typical rain cap. Exhaust PVC is 2.5 inch diameter.
Tonight it’s calm here for the first time in 4 days and the furnace is completing heating cycles normally. What can be done to keep gusts from creating pressure waves down the flue or wind-capping the flue ?
If it was me I would contact the MFG and see if a different type of safety switch/device could be used. You referenced exhaust PVC I assume a 90 % furnace. Are the exhaust and the intake combustion air a combo or are they seperate the reason I ask is the combo may solve your problem alaska is not the only place with strong winds with Texas sucking and Kansas blowing Okla has strong winds also