Underfloor heating - replacing thermostatic mixing valve

[melias]

I have a speedfit underfloor heating system and I think my mixing valve is not working properly. Water from the boiler is hot, but it's luke-warm when going into the heating manifold and no turning of the knob on the mixing valve will change the temp.

I've purchased a new valve and would like to change it myself.

I understand that I need to shut the flow to and from the boiler, but what will happen when I remove the old mixing valve? Is the water in the UFH system under high pressure? If so, do i need to re-pressurize it after replacing the mixing valve?

Apologies for the amateur questions

 

[Richardthe3rd]

I have a speedfit underfloor heating system and I think my mixing valve is not working properly. Water from the boiler is hot, but it's luke-warm when going into the heating manifold and no turning of the knob on the mixing valve will change the temp.

I've purchased a new valve and would like to change it myself.

I understand that I need to shut the flow to and from the boiler, but what will happen when I remove the old mixing valve? Is the water in the UFH system under high pressure? If so, do i need to re-pressurize it after replacing the mixing valve?

Apologies for the amateur questions

Generally each loop on the UFH manifold is valved. Just shut all the valves, but ensure you take a note of all settings on each individual valve.
HTH

 

[Norcon]

Should be isolators into the manifold.