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  1. #1
    Join Date
    May 2015
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    Northern Virginia
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    Power vent water heater

    I was checking on a boiler today and noticed the 3" PVC vent was discolored on a RUUD 75 power vent water heater. The white of the pipe was actually a reddish brown color from the motor connector out about 8' that I could see. I tested the temperature when it was fired and it was bouncing between 140-150F with my laser gun at the top of the unit. Does this draw any concerns? I know the condensing boilers can be around 140F but I think it's unusual to find it like this. Any thoughts?

  2. #2
    Join Date
    Aug 2002
    Location
    Southold, NY
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    PVC has a 140* max rating.
    There issue?

  3. #3
    Join Date
    Sep 2007
    Location
    edmonds wa
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    Manifold gas pressure checked?
    UA Local 32 retired as of Jan 2020

  4. #4
    Join Date
    Jul 2018
    Location
    Wisconsin
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    A standard powervent waterheaters exhaust is mixed with room air to cool it. Make sure your air inlet is clear on the back of the powervent assembly.

    Sent from my SM-G960U using Tapatalk

  5. #5
    Join Date
    May 2015
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    Northern Virginia
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    Thread Starter
    It is a 2PSI gas system with a Maxitrol regulator so that would be a good check. I was curious to know what temperature the stack should be. Yes the gas pressure certainly could be an issue. It's an 05' so it's been like this for awhile. I will check it and get back to this thanks.

  6. #6
    Join Date
    Oct 2018
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    23
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    2PSI gas system is the best option for you.

  7. #7
    Join Date
    Sep 2007
    Location
    edmonds wa
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    I would also verify the ventor wheel is clean and the vent pipe is clear and installed per specs along with adequate combustion air.
    UA Local 32 retired as of Jan 2020

  8. #8
    Join Date
    Aug 2002
    Location
    Cincinnati, Ohio
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    If you are venting into Schedule 40 PVC the flue temperature cannot exceed 140 degrees or the pipe will separate. When a water heater scales up the flue temperature can get much higher. The limit in the exhauster is usually around 170 degrees which makes no sense?
    captain CO

  9. #9
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    May 2015
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    Northern Virginia
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    Thread Starter
    https://www.phcppros.com/articles/19...for-flue-gases

    So to your statement about scaling this article which is well written states like you have Jim that with the excessive temperature rise due to scaling will compromise the material and create a possible CO condition. Ron George suggests that a high limit device installed in the stack would prevent this condition like you mentioned and 170 degrees is unacceptable. I know the grey CPVC is expensive and some condensing equipment manufacturers such as Veissman only allow the CPVC as a plastic venting option and I believe that allows a temperature of up to 200 degrees. This thread has become a good eye opener. Thanks to everyone.

  10. #10
    Join Date
    Mar 2015
    Location
    Hamersville, Ohio
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    Quote Originally Posted by Jim Davis View Post
    If you are venting into Schedule 40 PVC the flue temperature cannot exceed 140 degrees or the pipe will separate. When a water heater scales up the flue temperature can get much higher. The limit in the exhauster is usually around 170 degrees which makes no sense?
    Hos 4:6 My people are destroyed for lack of knowledge. Because you have rejected knowledge, I will also reject you, that you may be no priest to me. Because you have forgotten your God’s law, I will also forget your children.


    "You've got to Stand for Something or You'll fall for anything" (A. Tippin)


    Mat_15:24 But he answered, “I wasn’t sent to anyone but the lost sheep of the house of Israel.”

  11. #11
    Join Date
    Mar 2015
    Location
    Hamersville, Ohio
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    Quote Originally Posted by Spitz View Post
    A standard powervent waterheaters exhaust is mixed with room air to cool it. Make sure your air inlet is clear on the back of the powervent assembly.

    Sent from my SM-G960U using Tapatalk
    Hos 4:6 My people are destroyed for lack of knowledge. Because you have rejected knowledge, I will also reject you, that you may be no priest to me. Because you have forgotten your God’s law, I will also forget your children.


    "You've got to Stand for Something or You'll fall for anything" (A. Tippin)


    Mat_15:24 But he answered, “I wasn’t sent to anyone but the lost sheep of the house of Israel.”

  12. #12
    Join Date
    Mar 2015
    Location
    Hamersville, Ohio
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    Quote Originally Posted by pecmsg View Post
    PVC has a 140* max rating.
    There issue?
    Hos 4:6 My people are destroyed for lack of knowledge. Because you have rejected knowledge, I will also reject you, that you may be no priest to me. Because you have forgotten your God’s law, I will also forget your children.


    "You've got to Stand for Something or You'll fall for anything" (A. Tippin)


    Mat_15:24 But he answered, “I wasn’t sent to anyone but the lost sheep of the house of Israel.”

  13. #13
    Join Date
    Mar 2015
    Location
    Hamersville, Ohio
    Posts
    7,281
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    LRB,

    Have You got a Md# & Ser.# for that DHW?
    Hos 4:6 My people are destroyed for lack of knowledge. Because you have rejected knowledge, I will also reject you, that you may be no priest to me. Because you have forgotten your God’s law, I will also forget your children.


    "You've got to Stand for Something or You'll fall for anything" (A. Tippin)


    Mat_15:24 But he answered, “I wasn’t sent to anyone but the lost sheep of the house of Israel.”

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