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Discuss Mixer valve set up not controlling temperature in the Underfloor Heating Forum area at PlumbersForums.net


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Initial begatube UFH system, 6 zones downstairs and 7 rads upstairs. 1 zone. I know thats rbbish but was new build and thats what i got not knowing any difference.

The manual 3 port mixing valve and thermostatic heads.. I've replaced twice since.

I had new vouge c40 combi boiler in April to replace powermax 155x which could never cope from off really.

I had brand new 3 port mixer, brand new thermohead and brand new pump fitted last month. First few weeks all great. What I set thermohead to, it was within few degrees, so didn't need to rely on reducing boiler CH outflow lower.

My wiring centre then blew, literally, and I discovered faulty accuator head. New accuator and 8 way wiring centre now in. UFH actually controlled by thermoflash, and each zone has wall stat to control accuators.

The pump still runs now even when accuators closed until digiflash system turns off. The wiring centre simply does not control pump other than being over ridden as always on when UFH on.

I set the boiler CH timer to come on with digiflash UFH. Rads upstairs obviously on same time but managed by TRV.

Not good but it works, well did.

Now no matter what temp.i set mixing valve for UFH at (it can't ever go above 55 as will damage floor screed?) it only comes down if I turn boiler CH flow temp down!

It's as if mixing valve ain't there or thermohead!! It's done it b4 which is why I bought all new stuff.

Only mechanical issue left is a slight ball valve leak at UFH isolation valve at flow in. And it's slight, maybe 5 drops every other day. Boiler pressure still ok and I can top up manually anyway

When I take thermohead off and physically press down on mixer nipple I hear it mixing but temp.only comes down few degrees at best.

Has my brand new mixing valve packed in again after 2 weeks? I bought another thermohead in case that brand new one was faulty....makes no difference, may as well not be on.

Any ideas???? Thanks






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Please help anyone?!
Hi there,

as you've said - looks like the mixing valve doesn't do anything.
I've done some research and I think replacing your mixing valve with Esbe VTA232 will be the best option. It has to be the 323 version as it will have flow, return and mixed water at correct ends.

You might need to move your existing pipework a bit but unfortunately that needs to be done.
Esbe VTA323 are available in 2 versions 15mm and 22mm (compression connections).
If you wish to know the prices please email me on [email protected] and I'll check them for you (it's not a stock item).

Hope that helps.

Uheat – Wojtek

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