Adjusting the Temperature Limit Stop on Shower Valves

Discussion in 'Tutorials' started by jadnashua, Feb 28, 2016.

  1. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    All modern shower valves have anti-scald technology which includes two different parts:

    - Antiscald, often by the use of a pressure balance spool valve

    - A temperature limit stop (or calibration, if it is a thermostatically controlled valve)

    When set from the factory, they are often set for ‘typical’ incoming water temperatures, which may not match yours, especially if your cold water is very cold (like in the winter) or very warm (like say you live in Arizona in the summer). The valve has some means of adjusting how much hot can be used, and generally starts out all cold, then gradually mixes in more and more hot up until it reaches the stop.

    Different manufacturers, and even within the same one based on the model line and type, will have different methods to change that maximum handle rotation that controls how much hot water you can get out of the valve.

    Thermostatically controlled valves are often pretty close to being accurate, and will adjust their output based on the incoming water temperatures to provide a much more consistent outlet temperature…all a single handle valve does is adjust the mix of hot and cold, and if those sources change their temperatures (like say, you’ve used up a lot of the water tank’s hot water and that is starting to cool off), the outlet temperature will change. The biggest change is often the seasonal one that affects the cold water inlet temperature. So, if the stop is adjusted to just get the max safe temp in say the winter, it will likely be too hot in the summer when the cold water is much warmer, and vice-versa…if done in the summer, it may not be hot enough in the winter since the cold water is MUCH colder and will dilute the water temperature much more.

    First thing to check is that you have opened any in-line shutoff valves FULLY prior to adjusting the limit stop on your actual shower/tub valve!

    Here are some links to some various brands videos on how to adjust shower valves:

    Delta https://youtu.be/n2_uZ7wgV1I

    American Standard (not an AS video) https://www.bing.com/videos/search?q=youtube+american+standard+limit+stop&view=detail&mid=1949914A86B03CCB4AFD1949914A86B03CCB4AFD&FORM=VIRE7

    Pfister https://youtu.be/kiCwvOGXj1A

    Moen (not a Moen video) https://youtu.be/0i96DV_8d1c

    That covers the majority of those commonly available, but the best thing is to keep your original installation instructions and follow those, as they do make changes. These videos should give you a good idea, and you can probably figure it out after watching one or more of these. To be safest, you should use an instant read thermometer, and check how hot things actually can get, as defeating this safety feature by allowing it to get really hot, can be dangerous!

    Jim DeBruycker

    28 February 2016
     
    Last edited: Mar 21, 2016
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  2. Gary Swart

    Gary Swart In the Trades

    Joined:
    Sep 1, 2004
    Location:
    Yakima, WA
    I've only done this on two, so I don't have any fancy devices, but I used an ordinary thermometer to set them. May not be scientific, but they work just fine.
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    A 'normal' thermometer will certainly work, it just takes longer.
     
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