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Vibrating water heater power vent PVC pipe assembly

0 votes


Vik says:
January 9, 2011 at 9:20 am
This is a very useful site. Thanks.
I recently had my water heater replaced. The previous and new water heater use forced venting via a 3" PVC pipe (~ 35ft long). There are two 90 and two 45 degree elbows. The motor at the top of the heater vibrates when it runs. We have changed the motor and it does the same thing.  
The problem is that when the PVC pipe is connected to the motor and the motor is running, one can feel vibrations in the control box/gas pipe connected to the water heater. If the PVC pipe is disconnected (and the motor is running – for testing only), there are no vibrations in the control box/gas pipe.
Clearly the PVC pipe connection is stiff enough that motor vibrations are transmitting to the body of the water heater and to the control box/gas pipe. The installer, in consultation with Bradford White, placed two PVC rubber coupling – one close to the blower and the other at the middle point of the longest run of the PVC pipe. This has reduced the vibrations at the control box/gas pipe but not completely.
My question is this: Can we replace the stiff rubber couplings with some flexible, high temperature coupling? Something like this: http://www.flexaust.com/insulated-dryer-hose
I’d appreciate any comments.
I’d welcome any suggestions.
asked in Gas Water Heater by darekrudy (21,730 points)
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1 Answer

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Hi Vic,
Thank you, I’m trying  …
As I recall, a couple of years ago, I was inspecting a 6 flat in Chicago. There was six Bradford White power vent equipped water heaters and they all had noise and vibration problem, but I’m not sure how did they correct this issue. BW might have a large quantity of the motor assembly in stock and until it runs out / is replaced with a vibration free batch, they will have to keep exchanging it for the customers.
I wouldn’t go with any type of the vent pipe that it’s not approved / listed for the power vent water heater venting, by the WH manufacturer, and by your local building department. Power vent equipped water heaters (as described in their installation manuals) are designed for PVC, ABS or CPVC vent pipes only.
Properly balanced and cushioned power vent water heater motor assembly should not produce any significant vibration and I’ve seen many of those units (not only Bradford White) that are very quiet and you can barely feel them vibrate. Problem with power vent motor vibration is that it might eventually cause the WH vent pipe seals to break (even with the rubber couplings installed) and the motor assembly enclosure, gas regulator / components to separate.
I wouldn’t stop complaining until this issue has been resolved by the manufacturer and I would definitely not use any un-approved by the manufacturer components – this will void your warranty.
Let me know what happened.
answered by darekrudy (21,730 points)