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Thread: Hot water recirc line w/ instant water heater?

  1. #1

    Default Hot water recirc line w/ instant water heater?

    I have an instant water heater (as backup for solar heated water) and was wondering if anyone has any experience using a hot water recirculation pump with a demand heater.
    I understand that I will be circulating hot water back through the demand heater. Mine is designed to be used with preheated water, and has a modulating gas valve to turn off the flame when not needed.
    I just want to hear about any other issues folks might have run into with this setup.

    I do not have a return line, and have been looking into the valves that return back hot water into the cold line. Any thoughts?

    Thanks and Happy Labor Day!

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    If you read the instructions, those that I've looked at specifically say do NOT use with a recirculator. Yours may be different.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    In the Trades Gary Swart's Avatar
    Join Date
    Sep 2004
    Yakima WA


    I believe this would overwork the on-demand heater causing early failure. There are recirculating systems that do not require a return line, but I would suggest that if at all possible you install a return line and use a recirculating pump designed to be use with a return. I have such a system in my home, and it works very well.


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