Tankless get flue staining Insulation

Tankless HWT PVC pipes/flues. One goes through the roof, the other terminates in attic and is staining foam insulation. Can anyone provide me with information on what’s occurring or if this is proper installation.

From NE Okla., it looks like the attic is sealed with foam insulation. If so, the exhaust and combustion air needs to be outside the envelope. Also, what appears to be spray foam on the water heater is worrisome.


Hopefully those 2 pipes in the attic aren’t reversed. It sure looks like though.


yikes. that would explain the staining alright!

How do you service it? retardation next level!

Without make or model there’s no way to determine if combustible air can be brought in from the attic space. Looks to me like the vent and intake are reversed. Just call it out for evaluation and repair by a licensed plumbing contractor.


Yes it does Thomas.

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