Dual water heaters with recirculating pump

Discussion in 'Water Heater Forum, Tanks' started by LeonUGA, May 28, 2009.

  1. LeonUGA

    LeonUGA New Member

    May 28, 2009
    I am interested in installing a Grundfos UP15-10SU7P/TLC recirculating pump on a dual water heater setup. The tanks are presently installed in parallel with the two outlet lines rising overhead to tie in to the horizontal line. I am unsure where the Grundfos pump should be installed on this particular setup. Should I change the setup so that both tanks merge into one vertical rising pipe and install the pump on that single pipe or should I install the pump "downstream" from both tanks to circulate the water away from the tanks toward the far end of the house to the bathrooms where the transfer/comfort valve is located?

    Attached Files:

  2. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Nov 20, 2008
    Chicago Illinois Licensed Plumber
    Chicago, IL
    Your parallel installation is wrong. The heater on the left is doing all the work. The piping that enters each heater must be exact in every fitting and length, as well as the hot water piping. Both must be exactly the same in length and fittings. If one pie is longer on one heater verses the other the water will take the shorter pipe (path of least resistance).

    Here is a good PDF showing the proper way to plumb in duel heaters in parallel with a return line. http://www.hotwater.com/lit/wiring/315268-000.pdf
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