Technical directory · Combustion
PVC vent terminal blockage
High-efficiency furnaces often vent through plastic pipes to outdoors; snow, ice and debris can obstruct terminals.
What to observe
Locate the termination from a safe distance and note weather and fault codes.
A field example
Snow drifting over an exterior terminal after a storm can cause a lockout. Note the weather and location from safety; a qualified worker must verify the vent and operation without bypassing pressure controls.
What the written work should say
A qualified technician should confirm the vent path and appliance operation; safe exterior clearing depends on access and manufacturer guidance.
Where this task stops
Never defeat a pressure switch or operate a unit with suspected blocked venting.