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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Thermostatic mixing valve heating my cold tank!!! https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1264690845 Message started by pryantcc on Jan 28^th, 2010, 3:00pm

Title: Thermostatic mixing valve heating my cold tank!!!
Post by pryantcc on Jan 28^th, 2010, 3:00pm

Hi,
I got one of these thermostatic mixing valves last weekend to limit the water temperature at the hot taps in two rooms in our house which are used for childcare.

I was very suprised to find that the cold water feed to the unit very quickly heated up and convection soon resulted in the whole cold pipe from the attic tank to the mixing valve getting hot! This in turn means that the cold storage tank in the attic is also being heated!

Is it just me, or is this a major design flaw and waste of energy?

I'm also curious to know whether I could fit a non-return valve on the cold feed to the mixing valve to cure the problem?

Thanks, and sorry for so many questions today!

Paul

Title: Re: Thermostatic mixing valve heating my cold tank!!!
Post by thescruff on Jan 28^th, 2010, 3:51pm

What you are doing is controlled work commercially.

The mixer valve should have check valves supplied with them, unless they are cheap non compliant types, whereas you need to supply them. But they must be fitted.

Title: Re: Thermostatic mixing valve heating my cold tank!!!
Post by nozzle on Feb 12^th, 2010, 12:59pm

It could be calcium (limescale) build up on the check valves seats preventing the valves from returning to their closed positions.

If you live in a hard water area, then it might make sense to install a water conditioner adjacent to your TMV.