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Backdraft on water heater power vent PVC pipe

0 votes


Mike says:
January 2, 2011 at 11:11 am
My water heater is vented through the side of my house, with 3" PVC piping and terminates with a 90-deg elbow, pointed towards the ground. However, the vent pipe ends up on the western (wind-facing) exposure of the home, resulting in a significant draft being produced when the power vent is not operating. I have a separate fresh air pipe on the same wall.
My question is – can I install a trap-style vent cover on the home’s exterior in place of the PVC elbow? I feel that this would significantly reduce or eliminate the draft entering the house through the exhaust piping.
asked in Gas Water Heater by darekrudy (21,730 points)
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1 Answer

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Hi Mike,
Not unless such installation is permitted by the manufacturer and your local building department. I've never seen one in the field nor offered as an option in the manuals. To minimize or maybe even eliminate air drafts, try to put an offset on the PVC vent pipe and angle its termination end (last elbow) to the side. Find a position of that last elbow that results in the lowest air infiltration. 
Let me know if this helped or if you have any other questions,
Thank you,
answered by darekrudy (21,730 points)


Eugene says:
I am not a professional plumber, but I resolved this problem back in 2004. when I moved into the new house with high efficiency water heater I discoveed that when my water heater runs idle exhaust gases are not vented trough the exhaust pipe and escape into the basement.
So, I created an ad hock solution using a 4" T coupler and a 100 MM computer fan. That solution is still running great. I just replaced a fan after 6 years of operation. The same solution also works on my neighbor unit that has exatly the same model of water heater. It may look not professional but it fulfills the purpose.
Hi Mike, it’s a… solution  , but the WH power vent shouldn’t be idling. There’s always a reason behind it.