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Water heater power vent PVC pipe inside chimney

0 votes


Don says:
April 18, 2011 at 12:46 pm
First off, thank you for sharing your experience on this site! It’s the first website I’ve seen that has good information about venting a water heater!
I’m changing from a natural draft gas water heater to a power vented type.
The old one was attaches to a metal chimney it used to share with a furnace:the furnace has since been upgraded to a high efficiency model with dedicated intake and exhaust vents that route to the side of the house, so the natural draft water heater now has the 6? metal chimney to itself.
From what i understand I can’t attach a power vented water heater to a metal chimney, correct?
If this is the case, what are my options?
Could I sleeve a PCV pipe inside of the chimney for the power vented water heater?
Thanks for your time!
- Don
asked in Gas Water Heater by darekrudy (21,730 points)
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1 Answer

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Hi Don, thanks!
Correct, the metal chimney cannot be used to vent your new power vent water heater because all of the vent pipe components must be air tight. You can utilize unused metal chimney / use it as a chase for the new PVC vent pipe. However, there are a few things you should keep in mind:
1. Use the PVC vent pipe tables provided with the appliance to make sure you’re using correct diameters, number of elbows and length of the vent pipe
2. Water heater power vented system does not produce condensation but the condensation can form inside the CPVC, ABS or PVC vent pipe, especially in vertical runs.
The amount of condensation will depend on the environment; climate, metal chimney exterior exposure, proper seal at the top and bottom of the chase – at chimney entrance and roof termination, length of the vertical run. To prevent condensate from flowing back into the motor enclosure and contaminating it, make sure there is a proper condensate drainage kit installed.
3. Install 90° or 45° vent terminal + screen to prevent rain water and rodents / birds penetration.
4. You can seal the chimney and go through the side wall if it’s easier.
Let me know if you have other questions
answered by darekrudy (21,730 points)