Confused by room thermostat wiring

muckybutt

Note to OP :

Put 999 in your speed dial you or a relative / friend might need it

ziggyman99

Sorry my answer was a bit brief and should also have said..... check it out first. IF the wiring follows normal conventions then what I have told you will work. Worst thing that will happen is a blown fuse. It is fused at 3 amps isn't it?

victor2

What's a fuse?

ziggyman99

victor2 wrote: »

What's a fuse?

a type of sacrificial overcurrent protection device.

DominicH

Glad to have caused some amusement. But I have worked it out with the wiring diagram. No, it wasn't three-phase wiring . ziggyman99 was right. The blue wire was for an "accelerator resistor" which may be useful in old-school thermostats, but I don't think the new one's going to need it, so I'll just close that one off.

zax47

Be aware that a new electronic 'stat will probably want a neutral present in order to work - rather than just be a mechanical switch within the live "line" (live in, switched live back out) like your old mechnical one was. You might find you have to put a new cable in anyway, or at least adapt the connections at the boiler end in order to provide this neutral to the 'stat. Either way it ought to be connected via a fused connection unit (FCU/"fused spur") fused to 3A max - it will confirm this in the instructions for your new 'stat. What make/model are you using?

DominicH

zax47 wrote: »

Be aware that a new electronic 'stat will probably want a neutral present in order to work - rather than just be a mechanical switch within the live "line" (live in, switched live back out) like your old mechnical one was. You might find you have to put a new cable in anyway, or at least adapt the connections at the boiler end in order to provide this neutral to the 'stat. Either way it ought to be connected via a fused connection unit (FCU/"fused spur") fused to 3A max - it will confirm this in the instructions for your new 'stat. What make/model are you using?

Thanks, but this one (a Philex model) explicitly says that any neutral/earth conductors must not be connected to it.