Ernco Coupling for Water Heater Flue Vent

Saw this Ernco coupling connecting a PVC flue pipe and B vent for a tankless water heater. Apparently this is an Ernco 1056-33 coupling designed for PVC and cast iron materials for drain, sewer, vent piping and waste applications. Specs say its resistant to chemicals, ultraviolet rays, fungus growth and normal sewer gases. How about flue vent gases? Looking for opinions on this since its composed of PVC and rated up to 140 degrees. Thanks.

The exhaust is under positive pressure and any formed condensate is very corrosive. B-vent is not meant for such use. As for the rubberized coupling, you’d have to check the heater’s installation instructions to see if it’s prohibited. Regardless, that setup is wrong because of the b-vent.

Just call it out to have a licensed plumber evaluate. PVC flue pipe should never connect to B vent metal pipe and the Fernco coupling is wrong as well.

^^^^^^^^^^ Simon and Martin are right on! ^^^^^^^^^^

It needs correction, not further evaluation – it’s clear as night and day that the installation is homeowner’s special, not that of a professional. The client is paying the HI money to know this, otherwise they would hire the plumber themselves instead of a HI. The only time a HI should defer is when it falls outside of the SOP and HI’s skillset as a “qualified”, and often “licensed”, home inspector and or invasive inspection is needed.