Check valve for gravity hot water re-circulation

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by bhoth, Apr 25, 2016.

  1. bhoth

    bhoth New Member

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    Ok I just removed the heat trap on both the hot and cold side in the second WH and the hot side on the first WH. It was a super easy job just grabbed it with a pair of needle nose pliers and it pulled right out.

    Crossing my fingers this does the trick and I am done messing with this!:)
     
  2. bhoth

    bhoth New Member

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    Well with the 3 heat traps removed as mentioned above, the hot water loop works better than ever until we turn on the shower. For some reason it still gets cold water added to the hot when the shower is on.

    Now what?
     
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Did you check the temperature limit stop?
     
  4. Widgit Maker

    Widgit Maker Member

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  5. bhoth

    bhoth New Member

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    Sorry I don't know what you mean, please explain.
     
  6. bhoth

    bhoth New Member

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    Would not this stop the flow of the gravity fed loop?
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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  8. Widgit Maker

    Widgit Maker Member

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    Bend the piping so that the input side of the check valve is lower than the output side. Indications are that the flow of water up the re circulation line (when faucet is opened) is not enough to close the check valve. Let gravity help it close.
     
  9. Widgit Maker

    Widgit Maker Member

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    No.


    You said the PVC check valve worked. Suggest you examine how it is made and how it works and compare it to how the the CPVC valve works.
     
  10. bhoth

    bhoth New Member

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    The difference is the pvc check valve was a rubber hinged pvc flapper valve. The cpvc is a ball valve. I could start by setting the valve straight horizontal. To do that I would have to add another 90 degree ( so from behind the furnace I would come straight out then a 90 degree turn straight down to the water heater)
     
  11. Reach4

    Reach4 Well-Known Member

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    I would try moving the recirc line to the second heater rather than the first. My hope is that the recirculation flow would increase, so the water in the recirc line would be warmer.

    The horizontal check valve seems to have some merit, or even maybe it should have a slight reverse tilt if that is what it takes to keep it open at low flow conditions, I would think.
     
  12. Widgit Maker

    Widgit Maker Member

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    That sounds like a vertical check valve. Does the ball float?
     
  13. bhoth

    bhoth New Member

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    The flow on the loop itself is actually very good since I removed the 3 heat traps.
    I have now modified the check valve with a 90 degree connection so the check valve is level. It was leaning downhill before. See pic below:
    [​IMG]
    No it does not float, the ball is actually not a ball, think of it more as a cup, the flow side is rounded but the back side is cup shaped to grab water and push itself closed.
     
    Last edited: May 9, 2016
  14. Widgit Maker

    Widgit Maker Member

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    Well, is it working? If so great, if not keep raising the out put side until it does . Being made of plastic and light weight the gravity flow will probably push the cup open even if the inlet side is tilted down as much as 45 degrees.
     
  15. Reach4

    Reach4 Well-Known Member

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    Where does the described cold water come from? If the water is circulating, the return line water should at least be warm. The bottom of the WH with a circulation current, while cooler than the top, should still be fairly hot, right?
     
  16. bhoth

    bhoth New Member

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    The tell tale is the next morning when my wife gets in the shower. So I will know tomorrow morning.
     
  17. bhoth

    bhoth New Member

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    I am assuming the bottom of the WH because if I shut off the loop, the shower instantly jumps hotter!
     
  18. bhoth

    bhoth New Member

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  19. bhoth

    bhoth New Member

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    Ok my wife says it's the same. So now I am moving the return loop from the bottom of the first WH to the second WH. Should I put back in the heat trap on the hot side of the first WH and the cold side of the second WH?

    Thank you,
     
  20. Reach4

    Reach4 Well-Known Member

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    I think it won't matter.

    Can you measure the temperature of the return water line? Maybe an IR thermometer could measure, or you could lay a probe along the pipe and wrap around the probe and pipe with a towel. A meat thermometer or candy thermometer (that is not also a deep fryer thermometer) should have a good range. Maybe if you measured the temperature before and after the pipe move, that could judge the effectiveness of the move. I think that higher return temperature would indicate more effective.

    If the horizontal pipe with the check valve has enough slack, it seems to me that you could tune the angle to what works best.
     
    Last edited: May 10, 2016
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