hot water recirculation pump connection to tank

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by fireman-175, Aug 27, 2013.

  1. fireman-175

    fireman-175 New Member

    Jan 19, 2007
    HI, I installed a loop hot water PEX system with three remote manifolds. As the hot water loop ends at the base of the hot water tank, it is met with a Grundfos UP-10 pump that I have fed into a check valve (correct direction) that is fed into the tank drain outlet.

    It works fine 95% of the time. Every now and then we get barely warm water when using solely hot tap water. The tank outlet is hot, the fitting at the recirc pump is hot, but the check valve itself is not hot, but warm. Then, all of a sudden it is hot water coming out.

    It is a swing check valve. Could it be bad already? Could some gunk from the aluminum decomposition (anode rod) be causing it to not open or stay open, thus allowing cooler water to back flow into the loop?

    Is there a better way to get the recirculated water back into the tank?

  2. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    we cannot tell you the condition of the check valve, but it it varies from real hot to cool, then the consensus would be that it is bad.
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  4. fireman-175

    fireman-175 New Member

    Jan 19, 2007
    I took it apart today and the swing check valve swung... I guess it works fine. I found more of that jelly gunk and feel that may have had something to do with the valve being held open a bit.. I also increased the temp on the recirc pump so it works more often. I replaced the aluminum anode as I read the water softener tends to corrode those faster and make nasty jelly at the bottom of the tank. I flushed it for a while. I used a tee and put a slight downward angle on the check valve to use gravity to keep it closed if the recirc pump is not on.

    Hopefully, it will work better. I will let you know. I used a combination alloy anode instead of another plain aluminum.
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