UFH blending valve blending too hot

Finally got my hands yesterday on a TMV from a acquaintance many miles away who reckons it has a range of 30C/50C.
It seems to work exactly as described above, the adjustment screw has to be wound right back (anticlockwise) to ensure the piston valve seats properly and stops any cold water passing.
I hadn't fully understood how the thermostat operates but can see now that as it heats up the plunger in the top is (hydraulically) forced up against the adjusting screw which forces the piston valve downwards to allow cold water to mix with the hot or shut the hot off completely if required, say in the event of cold water supply failure.

Here's a nice picture of one of these.


  • INTA TMV.jpg
    INTA TMV.jpg
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  • TMV Piston Valve.jpg
    TMV Piston Valve.jpg
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  • TMV Pretty Picture.png
    TMV Pretty Picture.png
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