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Dave Rose
05-07-2015, 03:56 PM
I had never seen this until today...is this acceptable? I wouldn't think so...wondering if the plastic will melt...but it was ok currently. The metal pipe is from a gas water heater, and the right one is a high efficiency furnace.

Positive pressure vents such as a hi-eff furnace should not be combined with a natural draft item such as the water heater...correct? If so, this vent is done incorrectly and the two should be separated. Comments welcomed.
Jerry Peck
05-07-2015, 04:41 PM
The problem is likely not going to be the plastic venting for the furnace, but rather that it is a positive pressure vent and the water heater and existing vent is (should be) a Type B gas vent for gravity venting (atmospheric pressure only).

Type B gas vents are not suitable for positive pressure use.

That may be your biggest issue, others here will likely add more that I am not including because ... correct the positive venting into a Type B gas vent and the other issues may also go away.

Just saying ... :)
Bob Harper
05-07-2015, 04:44 PM
That is type 'B' vent going into the ceiling which is approved for CAT I venting only, such as the WH. That furnace vent generates positive vent pressure, which is CAT III or IV. No, it is grossly illegal! Also, that storm collar could be hiding what is going on with the listed ceiling support/ firestop or lack thereof. The water stains are a red flag due to heavy flue gas condensation that has probably rotted out the B-vent. They must be vented separately but that B-vent probably is ruined. Would need to be reduced to 4" anyway. More pics?
Jerry Peck
05-07-2015, 07:20 PM
As Bob says...No gouda as Leslie Neilson would say. LOL

Surely, you can't be serious.
Dave Rose
05-07-2015, 08:03 PM
thanks all, good input. I will make appropriate comments.
Gregory Booth
05-08-2015, 05:08 AM
Surely, you can't be serious.

........don't call me Shirley
Jerry Peck
05-08-2015, 06:03 AM
Dead serious. I love the way Bob explained it. "No gouda" is a famous line from "Naked Gun 331/3" LOL


........don't call me Shirley

That's the reply I was seeking from Kevin as he referenced Leslie Nielson: "I am serious ... and don't call me Shirley.", from "Airplane".