Use a trap primer to bleed hot water into trap to have instant hot water?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by wiggerjw, Dec 20, 2017.

  1. wiggerjw

    wiggerjw New Member

    Joined:
    Dec 20, 2017
    Location:
    illinois
    I have been looking at recirculating pumps to help have hot water much quicker to my far-away kitchen sink... the I realized, why not simply have a small amount of hot water, just a drip, leak by in a bypass 1/4 in line hooked in tightly just above the trap. Like a trap primer would do in a laboratory setting. The idea would be to bypass just a small amount of hot water, so that the water in the line would not cool off (as much) as just staying there. Yes, it would be wasting some water, and some heat, but probably closely similar to the amount that is already wasted by turning on the hot water side and letting it run until it gets hot.

    And I have read the economics on buying and using a recirculating pump, this this is not cost effective either.

    Lastly, I have already insulated my hot water line as much as I can.

    Toughts, advice?

    John
     
  2. Terry

    Terry Administrator Staff Member

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    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    A trap primer uses so little water that you wouldn't notice any difference. Your water would still be cold.
     
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  4. plumber69

    plumber69 In the Trades

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    Jun 20, 2014
    Location:
    Prince Rupert, British Columbia
    Get this. Easy to install. No additional water lines required
     
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  5. plumber69

    plumber69 In the Trades

    Joined:
    Jun 20, 2014
    Location:
    Prince Rupert, British Columbia
    Or if you ran 1/2 PEX right of the hot water tank straight to the kitchen you would get hot water faster then 1/2 inch copper.
     
    Last edited by a moderator: Dec 21, 2017
  6. hj

    hj Moderator & Master Plumber Staff Member

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    trap primers ONLY work when someone uses a faucet, so the time between uses would normally be so infrequent, and short duration, that the line would NEVER stay warm, much less hot.
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    Constantly running hot water to the trap primer in a trickle is a bad idea, which is what I think you were indicating you thought about doing. Yes, it would keep the line hot if it was fast enough, but you'd be wasting water, energy, and paying for more sewer charges (and mess up your septic system, if you have that instead).

    SOme of the recirculation systems run the pump constantly, and use a thermostatically controlled valve to open and close to enable/stop the recirculation. Some, turn the pump on/off, and the pump's pressure opens the return valve. Each one has an aquastat to determine when the source is hot, so it doesn't pump hot water around when it is already there, minimizing the amount of hot water in the cold line if you don't run a dedicated return line. Shutting the pump off/on may save energy (mine does that, and is still going strong after 12-years or so), but it is more wear on the pump verses running constantly. I think over the life of the pump, running constantly would use more in electricity than it would cost to replace the pump should it die earlier. While mine could die any day, 12-years and counting of faithful service has to be worth something!
     
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