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Thread: luke warm water after new water heater install

  1. #1
    DIY Junior Member tyleraz's Avatar
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    Jan 2014

    Default luke warm water after new water heater install

    I just replaced my water heater because it was old, and it was still working fine but didn't want it to explode.

    Since then, the water in the house is lukewarm, and never gets hot. This was never a problem before.

    The water heater installer came by and said that the cartridge is bad in one of the shower handles and quoted me $150 for replacement. He said that cold water was being mixed into the hot water so it is not able to deliver hot water only. He turned off the hot water from the water heater, then turned on the hot water at the sink and cold water came out.

    I am curious, when the heater was installed, he told me to leave the bathtub water on for 30 minutes to clear out any debris that was in the line. Is it possible that some debris had caused the cartridge in the shower handle to have a problem as to allow cold water to enter into the hot water line? I appreciate any help. Thanks!

  2. #2
    DIY Senior Member JerryR's Avatar
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    Jul 2011


    Yes, it's possible and likely that debris from the old water heater could have found its way into the shower valve.

    I just replaced my 17 year old water heater because I found debris in a few sink aerators, hot water washing machine hose washer screen and a shower valve that was causing drips from the shower head.

    I drained the water heater and there was white sandy plastic debris in the water. I suspect the cold water dip tube was coming apart.

    Below a picture of some stuff I found in a bathroom sink aerator.

    Also I was getting slightly dis colored water when I ran hot water into the bathtub.

    With the new water heater all that is gone and bath water is much clearer.



  3. #3
    Forum Admin, Expert Plumber Terry's Avatar
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    Aug 2004
    Bothell, Washington
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    Electric water heaters from the factory are set pretty low.
    Do you have the same temperature everywhere in the house?
    If so, you might want to look at the thermostat setting.

    Some gas heaters are marked in letters.
    For Rheem, the "hot" setting is 120 degrees. A, B and C are hotter than that.

    If you have a "cross-over" at the shower valve, that needs to be fixed. Mixet valves can do that.

  4. #4
    DIY Junior Member Thomas Adair's Avatar
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    Feb 2014


    The debris might have caught up in the shower handle, it is a possibility. But that need not be the reason for the low temperature of water. First thing to do is check the thermostat readings in the house. Maybe it is set low. You should change that. Or it might be that something did go wrong when the water heater installation was in progress. But I think the thermostat will answer your doubts.

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