Electric Underfloor Thermostat Wiring help


I’m trying to update my current (UK) ‘Warmup’ electrical thermostat with a new z-wave one and have hit a wall with the wiring. Would anyone be able to tell me how I wire this old wiring:

Into this:

As you can see, I’m missing the additional neutral load connection in the new one. Does this mean the new stat isn’t compatible?

Any help appreciated :slight_smile:

The Neutral (N) terminal is used for both Input and Output. Should be: Blue for N and Brown for Live

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Thanks Finn, so basically you’re saying I need to wire the 2 live and 2 neutral wires into the singular live and neutral connectors on the new thermostat (seen below)?

Many thanks again for your help

All blue wires (except thermostat) to Neutral, incoming (old thermostat terminal 1)Live to L, heating elements live (old therm. terminal 4) to “out”

And please, cut the power off first :slight_smile:

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Many thanks again @FinnDRZ will give that a go tomorrow now :slightly_smiling_face:

So to update, got it all up and running but the back box of my old thermostat is too small to accommodate the large z-wave module, so it looks as though I’m now going to have to remove it and re-setup the old one. Sods law!


Try to find some kind of raiser, or mounting plate to lift the new thermostat?

Thanks Finn, but it’s just too far out. need to chase the wall, but I’d have to get someone in for that.

On a side point, I’ve left it wired to test out but the underfloor heating doesn’t seem to be heating up as quickly, or maybe even at all, it’s been on an hour (manual setting, so I’m not being scuppered by timers etc) now and whilst the old thermostat would’ve definitely made an impact by now, this one doesn’t yet seem to have done anything. Am I missing something here? Is it something to do with the voltage which displays ‘AC85-260V 50-60hz’ on the new one, whereas the old one states: ‘230VAC 50hz’ - does this make any difference?

Many thanks again for your help.

The voltage range is OK. Is there some indicator which shows if the heating is on?

Yes, 3 wavy lines appear and it ‘clicks’ to show when it’s on (heat is set to 23 degrees, 18 is ambient temp), but it’s just not working, floor is still cold :frowning:

I’ve had a look at the wiring, maybe one of the neutral connections was slightly loose, so I’ve re-done it and we’ll see what happens…

If you have a multimeter, check the output voltage between terminals N and OUT. On heating mode, the voltage should be near 230VAC (same as input voltage between terminals N and IN)

I tightened up that neutral and all seems to be working, I must have loosened something whist fitting it! Many thanks again for you help, just hope I can get this sitting flush now :confused: