Gurgling in Vent

Fellow Inspectors,

New construction, two zone system. The basement unit is a condensing furnace, with concentric vent exiting front bsmt. wall about 30-35 feet from unit. All visible vent pipes were pitched toward furnace. While doing the exterior, I heard a gurgling sound coming from the vent. My suspicion is somewhere along the run, water (condensation) is trapping the exhaust, then enough pressure is created and the vent gasses pass through the water and the sound is created. There was water draining from the unit into the sump as you would expect. Has anyone seen / heard this before?

I did write it up. And of course the attic furnace was not operational, so I will be returning to do another final walkthru.


All I can think of is that it may possibly have construction debris in the vent pipes causing the water gurgling through as you described.

The “gurgling” as you describe it is almost always caused by a clogged or partially clogged condensate line or Internal componant of the condensate drain system. If you could list the Make and model number of the furnace, it might help me with the problem. Best step though would be to get the client to have a qualified tech. have a closer look into the furnace to ensure it isnt the beginnings of a larger issue. I dont exactly agree with David’s above posting. 99% of the time if any one of the vents (intake or exhaust) are plugged or blocked, the furnace will fail to run or lock out due to the air prooving switches failing to close (blocked exhaust) or the rollout saftey switch opening due to lack of combustion air (blocked Intake)