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Thread: Hot water recirc. pump problem:Hot from cold faucets

  1. #1

    Default Hot water recirc. pump problem:Hot from cold faucets

    I have a very wide home with the water heater on one end. I have had a hot water recirc. pump for two years and it is fantastic. A couple of months ago, I noticed that hot water was coming out of several faucets near the hot water heater (and pump). I have checked all valves in the house to make sure water is not "crossing over". When I turn off the pump, the problem goes away. Any ideas?? Thanks, Dave

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    The systems usually have a check valve in them...did you check that valve? Sometimes it is in the pump, often it is separate.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3

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    There is a check valve right next to the pump. Also, the pump is quite hot. I don't know how you check a check valve?!

    Dave

  4. #4
    Moderator & Master Plumber hj's Avatar
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    You cannot check it directly, but it is not the problem anyway. If it were, you would get cold water at the faucets at the far end of the houise, not hot water at the closest faucet. Does your house have a dedicated circulation pipe, or did they install something like the Grundfos, "Comfort series" pump and valves? In a "normal" system, what you are describing cannot happen.

  5. #5

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    You nailed it. It is a Grundfos 15-18 pump. There is no timer or thermostat that I can see, so it runs 24/7. The return line is very hot, goes through the pump, through a check valve (at least that's what I think it is), through a Tee (with the drain) and back into the bottow of the water heater. The strange thing about it is that it was working fine for 2 years before this started happening. I was wondering if there could be air in the system or something like that. Any help or ideas would be appreciated.

    Thanks,

    Dave

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
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    Don't most of those systems have a thermostat to shut themselves off at some point? If not, basically, you are filling your cold water line with hot water. The system I have was all of a 5-minute install, and easily removed, if desired. Redi-Temp. It comes with a timer and an adjustable thermostat, so you choose whether you want that water hot or warm at the furthest point, thus also limiting how hot the return line gets. If it just started happening, my guess is that it has a thermostat that died. My unprofessional opinion.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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