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Discuss What is wrong with using a manual mixer shower with TMV? in the Bathrooms, Showers and Wetrooms area at

  1. Ric2013

    Ric2013 Plumber

    Given that cartridges are so b----y expensive, is there a very good reason, when the shower has proper independent feeds (such as a pumped shower) not to use a manual mixer with a TMV on the hot, thus limiting the maximum temperature to a safe level.

    Disadvantages I can think of:

    1. Not suited to gravity due to restriction caused by TMV setup (check valves).
    2. With a combi boiler, use of other taps might result in fluctuations in temperature achieved at the handset, so not ideally suited to combis, but would be safe at least.
    3. With a pumped arrangement, shower temperature will need readjusting as cylinder temperature cools, but other than that, should work well.
    4. You could only do this when the TMV can be mounted on the wall right behind the shower and is easily accessible.


    1. Cost
    2. Life of shower not limited to spares availability of the most unreliable component: the cartridge.
    3. A failed TMV can always be replaced quickly with off-the-shelf components when downtime is a concern, such as in a rental property or where there is only one shower.
  2. SimonG

    SimonG Trusted Plumber

    I like a really hot shower, others prefer it cooler.

    If you have a family of 4 are you going to fiddle with the tmv every time the shower is used.

    Mains cold temp fluctuations.
  3. Ric2013

    Ric2013 Plumber

    My mistake. I meant set the TMV to the maximum temperature and then each user can vary the temperature by using the settings on the manual mixer, not use the TMV as the temperature adjustment.
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