btw i have the same issue on my HE home furnace.
and just by chance, the billing department manager at the
furnace company i use has the same problem.
i did see an online article which mentioned some solutions.
NOTE that exhaust pipe condensate drainage is the first
thing i noticed appropriate to my problem.
If you experience a shut-down of your high efficiency furnace and suspect it’s related to a venting issue, check for these common venting problems:
Incorrect sizing of the exhaust pipe. Manufacturers specify the maximum length and number of elbows that pipe of a given diameter can have. And most high efficiency furnaces require 3″ diameter pipe. If you’re not sure check the furnace’s installation manual (if available) or contact the installing contractor to verify the pipe is sized correctly.
Not enough hangers (or straps) to support the exhaust pipe. If sags develop in the exhaust pipe, condensate moisture will pool in the low spots, creating enough blockage in the vent to trigger a shut-down. This is especially true during colder weather, where longer run times produce more condensate moisture.
Incorrect slope of the exhaust pipe; sloping downwards towards the outdoors (on sidewall vented furnaces). This pipe must slope back towards the furnace approximately 1/4″ per foot, allowing condensate to drain freely back into the furnace.
Vent terminations positioned too close to the ground. Show drifts or accumulations can block the vent, or ice buildup (see photo) can reach the vent and create a blockage.
Having the intake and exhaust vents installed on different sides of the home. The pipes MUST be terminated on the same side of the house, in close proximity to one another, so that the wind pressure is the same on both pipes.
Birds, insects or other critters have made their way into the vent. I’ve run across this problem many times. Unfortunately there’s not much that can be done to prevent this from happening, and removing these uninvited guests should be done by a qualified hvac technician....'