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Recirculating hot water pump

After installing the pump at the hot water heater outflow it states the bypass valve should be installed at the most distant point in the system. Might sound dumb but how do I determine where this is? Main goal is for instant hot at the main shower. Most videos show it being installed under a bathroom sink. Thanks for any help.


  • Jamie Hall
    Jamie Hall Member Posts: 23,324
    Not dumb at all. Some houses have plumbing which is... all over the place. If you can't actually see the pipes, just pick the area physically farthest. However. If you are particularly concerned about one particular bathroom unit, pick that one and don't worry about the rest.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,304
    Hi, One way to determine the furthest fixture is, first thing in the morning run hot water from one tap. Time it in seconds until the water is warm enough. Next morning, same thing at another tap. Do this for all likely suspects and you'll know which tap has the most water in the line between it and the heater. That's where the bypass should go.

    Yours, Larry
  • Alan (California Radiant) Forbes
    Since you can't get to the piping in the shower, install the bypass under the lavatory (bathroom sink).
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Dave H_2
    Dave H_2 Member Posts: 556
    You don't have to install just one bypass valve, I look at installing the valves in what I call "critical areas." My critical areas are the primary bath and the kitchen in my house
    Dave H