Swap dial thermostat to Heatmiser?

Andeh1 · Dec 3, 2023

We have a Heatmiser zoned UFH throughout our new build property, and then a couple of radiators in the attached garage (for possible conversion should we require it).

Builder's electrician installed a dial/rotary thermostat (Honeywell T6360B 1036) but I would like to change this stat to a Heatmiser V2 one - just to be able to monitor temps and potential turn on rads remotely.

I swapped it over, using the wiring diagram that Heatmiser provided, and whilst the Heatmiser stat works & looks to respond to my commands it isn't switching the Zone valve/turning on the ASHP. The old dial on worked fine!

Is there anything obvious I am missing here? Any recommendations?

Thanks

poni · Dec 3, 2023

I think you have got the grey and black wires crossed over, I am surprised that you did not blow it off the wall , hope it will still work after this

Andeh1 · Dec 3, 2023

Thanks poni,

II replaced the dial thermostat and confirmed that I havnt damaged anything, and it still works and activates the heating!

Heatmiser stat looks to be OK, I'll try and reverse the grey and black.

I thought grey is neutral and black switched live though?

Richard-the-Ninth · Dec 3, 2023

Andeh1 said:
I thought grey is neutral and black switched live though?

It depends who wired something as to what colours they chose to use. It could also be said it should have coloured sleeving to denote what does what, but it hasn't, that's life.

SPECIAL LOCATION · Dec 3, 2023

You have the wiring diagram for the new thermostat...
But.. did you refer to the wiring diagram for the old thermostat..?

i.e. which terminal is switched live out?
"3" is typically used as switched live out on other similar Honeywell thermostats!!

In BS7671 Brown Black and Grey are all live conductor identifications..
So assuming one is used as a neutral without any further cable identification is very bad practice.

Andeh1 · Dec 3, 2023

Thanks for the posts, I swapped grey and black round and it's working fine now!

Appreciate the support, reminds me why I avoid electrics as much as I possibly can!!!