Grohe 34126 thermostatic valve problem

Discussion in 'Shower & bathtub Forum & Blog' started by jalmora, Mar 7, 2013.

  1. jalmora

    jalmora New Member

    Messages:
    4
    Location:
    Alaska
    Hey there. I purchased a Grohe 34126 thermostatic valve in 2006. Installed in 2009. Been just fantastic all this time, but recently I am unable to get really hot water, the kind that makes you want to stay in the shower. I can get hot hot elsewhere in the house, but not the shower or tub. It hits a certain moderate temperature and will not increase. A lot of the info I find out there is for new installs, but mine was working just fine and only recently has been a problem. Any ideas? Thanks.

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    Last edited by a moderator: Mar 7, 2013
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,937
    Location:
    New England
    YOu may need to check the inlet filter screen or check valve for crud...it may have a restriction, preventing it from getting more hot into the valve. IF that doesn't fix it, it may need a new cartridge.
  3. jalmora

    jalmora New Member

    Messages:
    4
    Location:
    Alaska
    Total nonplumber here. What do you mean by the cartridge? I won't be doing this myself, but am trying to gather information for the nice guy who will. Thanks for responding, btw.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,937
    Location:
    New England
    The moving parts inside are typically called a cartridge and are replaced as a unit. Many of the Grohe valves have a little set of checkvalves in them - those have a small moving part, and a filter screen. If that gets jammed up, it will disrupt the flow. Same thing with the inlet filter screens (most of the Grohe valves use them). If you're on a well, you may have some occasional sand that gets in the system...that could clog some things up eventually. It could come through the town's water system, but isn't as common.
  5. jalmora

    jalmora New Member

    Messages:
    4
    Location:
    Alaska
    Thank you Jim.
  6. jalmora

    jalmora New Member

    Messages:
    4
    Location:
    Alaska
    If this double posts, sorry. We received from Grohe and installed a new cartridge. We cleaned the filter screens. Now we get scalding hot water for the first approx 5 seconds before it adjusts to that same "just below comfortable" moderate setting. We can get very cold water on demand, but not that good shower temperature. Any ideas?
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,937
    Location:
    New England
    Did you follow the calibration procedure on the new cartridge?
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