Navien PVC vent

[Jonathan Nielson]

I inherited a Navien Tankless heater when we bought our new house. I am now learning that it was never inspected and probably installed by a "buddy". I am changing the pex lines that seem to need to be changed for the condensate line, but the 2 inch pvc vent from the unit is sent up through an old galvanized vent roof stack. No other issues in performance, but the gas system is due to be inspected now after some new gas line work. Is it fair game to run the pvc up the old stack? Or do I need to get a new boot and pvc cap? If so what options do people like? no need for a concentric vent with a separate air supply already in place.

Thanks in advance for any and all advice.

 

[Jeff H Young]

2 inch pvc going through the b vent shouldnt hurt provided you extend above the b vent termination and flash it properly .

 

[Sponsor]

 

[Fitter30]

If you don't have the install manual there on line. Check the flue length and ells that they don't exceed what is in the manual.

 

[John Gayewski]

There are too many specific details left out of this post to know what your saying. If your asking to use the old atmospheric vent piping as a conduit path for the pvc to run through yes it's fine. If it's just blowing up into the old vent pipe it's not fine. Navien technically let's you grab fresh air from inside of the building as long as the room is big enough or there's a adequate ventilation, but it's not the right way to do it as it's creating a vacuum in your house and bringing outside air in, which take effeciancy away from your hvac.

 

[Jonathan Nielson]

I appreciate the replies, we are planning to replace the roof vent and install a new jack around the 2 inch vent.

 

[Breplum]

I've installed dozens of Navien tankless using 2" pvc straight up through the top of old B vent.
I drill hole, push pipe through, caulk with silicone and use a rain collar and silicone the margins and have never had an issue.