THermostatic Mixer Showers not as hot as bar mixer shower


13 Oct 2014
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United Kingdom
We have two types of showers a Thermostatic contemporary Mixer Shower plus hand held diverter and a bar mixer shower.

The bar mixer shower gives a very hot strong drenching shower. The built in Thermostatic Mixer Showers provide a warm shower. If the water is diverted through the hand held shower piece then the water temperature is still only warm. If we turn on the cold tap in the bath then the Thermostatic Mixer Shower give a very hot shower (as hot as the bar mixer shower).

The water pressure from the cold water is mains pressure and the hot water comes from the boiler tank which is part of an enclosed heating system. How can we adjust the pressure appropriately? Reducing the cold is not an option because it then goes below the minimum requirement of 2 bar (?).
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Nanny statism most likely the cause.

Had a huge barny with Grohe about the performance of their hideously expensive digital shower I fitted to my bathroom this summer. Ended up ripping it out and fitting Mira's Platinum which has been exemplary.


Find and read the manual for the unit and recalibrate it.

Most are factory set to a pathetic temperature that I am pretty sure it's more unhygienic than it is safe from scalding.

Also make sure the supplies are the right way round. That will confuse the mixer element.

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