Help with ufh wiring

Jmay1981 · 2026-02-09T15:06:31+0000

HI Guys

Im trying to wire up my wet ufh system to my boiler via heatmiser uhf4 wiring centre and a fastwarm wifi stat.

I want to run the underfloor heating through a seperate wifi stat rather than the the mechanical boiler stat.

I cant seem to get the stat to fire the boiler and the only way i can get it to work is to bridge it so it works with the normal central heating system.

PLease see below wiring diagram and close up of the boiler stat and wifi stat which hopefully might make more sense

Thanks in advance.

Jon

ericmark · 2026-02-09T15:47:18+0000

nothing connected to com so will not work, likely needs a link wire com to line. Also

they look disconnected?

Jmay1981 · 2026-02-09T17:31:01+0000

Hi Eric

Thanks for the info I’ve linked the com and also the lr and ls from the boiler.

The WiFi thermostat is now working and firing the boiler. But the central heating system won’t work now on the mechanical timer on the boiler.

The boiler is a Worcester 34cdi with a mt10 timer.

Any ideas how I would be able to get the central heating to work off the mt10 timer so that the ufh is controlled by the WiFi thermostat and the central heating can run off the boiler timer?

Many thanks

Jon

CountryFan · 2026-02-09T20:17:54+0000

Sounds to me like you may need zone valves, or perhaps a relay system

ericmark · 2026-02-10T00:02:29+0000

Sorry, I would not personally install UFH as to save money, I only heat rooms when in use, and the heat-up and cool-down times with UFH are too long for it to be a system I would want to use.

As far as I can tell, you need to use the heatmiser unit for all the heating, it has relays inside it allowing it to power zone valves, without having micro switches inside the valves, I am sure someone could cobble together some system which will work, but that person is not me.

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Help with ufh wiring

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