Hot water recirc line w/ instant water heater?

Discussion in 'Tankless Water Heater Forum' started by ffmedic7, Sep 4, 2006.

  1. ffmedic7

    ffmedic7 New Member

    Aug 26, 2006
    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. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    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.
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  4. Gary Swart

    Gary Swart In the Trades

    Sep 1, 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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