HVAC with plastic exhaust vent pipe ... need advice, Pics incuded

First time I have seen…



Plastic is used for condensing furnaces.

It’s likely a concentric vent meaning combustible air enters through perimeter opening while exhaust terminates in the center.

I could be wrong but it doesn’t look like a concentric. Notice there are two separate vents-one for the combustion air and one for the exhaust flues. It might terminate at a concentric fitting though.

Not that one. It has separate intake and exhaust.


Did you also notice there is no sediment trap?

When I see a condensing type unit that I am unfamiliar with, I look around for the manual which is usually nearby. It will give you the specs for the exhaust.

Often times, if the exhaust run is short, you will see a section of enlarged diameter pipe in the center to slow the gasses to aid in condensation. These vents must also be continuously sloped back toward the unit so that condensation can drain off.

Did they run that gas appliance connector inside the cabinet?

Whenever I see that many bends I check the manual.

You usually have to increase the pipe size if you have too many bends.

Can’t get the pic but plastic is the norm with the high efficiency units as they said

Should be schedule 40 .
Hope they had proper sealant.

Also make sure both pipes terminate correctly at exterior.

Thanks everybody… That enough
Info… For me to recommend a
Licensed HVAC Contractor to evaluate

Why do you want him to evaluate it?

You can’t tell from this photo. If done correctly, it would be after the valve which would be out of sight in this picture. Could be at the transition to hard pipe where it goes into the cabinet.