Honeywell T40 upgrade to RT500RF

[KingTurkish76]

Hi everyone.

I have an old Honeywell T40 room thermostat.

At the moment, wires feeding the thermostat are as follows:

Brown - to terminal 1
Blue - to terminal 3
Earth

Now looking at the diagram on the T40 casing there should of been a third wire neutral. Not only that, but it looks to me like the wires above should of been round the other way, but I'm guessing as it's a switch it doesn't really matter.

So, onto the RT500RF. We have inside terminals for N/O, Com, L and N.

Here is what I think I should be doing.

The brown goes to Com
The blue goes to N/O

Thanks for any re-assurance or suggestion.

 

[D_Hailsham]

So, onto the RT500RF. We have inside terminals for N/O, Com, L and N.

Here is what I think I should be doing.

The brown goes to Com
The blue goes to N/O

That's OK, so far as it goes, but you also need a permanent live and neutral to the L and N terminals. This is required to power the electronics in the thermostat's receiver.

 

[KingTurkish76]

oh yeh, that's the easy bit, bung on a fused switch and away we go.

Thanks for the help.

 

[D_Hailsham]

oh yeh, that's the easy bit, bung on a fused switch and away we go.

It's advisable to have all boiler electrics fed from the same supply. That prevents nasty surprises when someone turns off one switch, thinking it's all safe, only to get a nasty shock (literally ) when they start working on the controls.