In-line TMV, Will it make my bar mixer perform worse, due to it cooling the water down prior to it?

20 Mar 2006
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United Kingdom
I've got a fairly new build house that has an in-line TMV valve connected to the hot water tap on the bath. I have a thermostatic bath filler/shower connected to the hot water supply coming from the in-line TMV. The hot water is supplied by a combi boiler. The shower is ok, but I'm wondering could it better if the in-line TMV was not present? In-regards to the hot water supply actually being hotter entering the bar mixer, than being cooled down by the in-line TMV, adding cold water to the hot water supply presently.

I understand that the TMV is there for a reason, but the bar mixer is thermostatic and I don't have any young kids to be bothered about.

Thanks for any advice.
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The TMV is there As part of building regulations part G, removal of it would be in breach of this regulation. I don’t believe they should have fitted a thermostatic shower with a TMV, surely separate feeds would have been better?
No the builders didn't fit it, it was me. It was just by far the easiest way to do it. I'll maybe figure out a way to blank it off so it's not noticed. The house just originally had separate hot and cold water taps on the bath. I replaced it with a deck mounted thermostatic bar bath filler/shower mixer. So I guess that the water will be at a not to hot temperature, unless the override button is pressed on the temperature knob. Bit of a pain really if it has to be there, but really is not needed, and I guess could make the shower perform worse. Thanks for the reply.
The hot water is supplied by a combi boiler.
To be fair if it's a Combi the most efficient solution would be to turn the dhw target temperature to around 40-45c to get maximum condensation.
The tmv and shower valve should have a pressure loss curve in the manual, also you can look up the pressure loss per metre of pipe and elbow. Then you can understand where the problem you're seeing is.
You would also need to measure the dynamic pressure on the incoming supply in case the issue is outside the property
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If you have replaced the free flow taps that were on the bath to a thermostatic mixer shower tap, then as long as it complies with the TMV2(3) standard then the inline under bath TMV can be removed.

You are in effect replacing one anti scald device with another so the outlet would still comply with the regs. It must be certified TMV2(3) compliant though.
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