wiring in a new CM927 remote senor thermostate

[mel7938]

Hi

I have taken out the existing room thermostate which was wired up with 2 cables, 1 Live & 1 neutral.

The wiring diagram is showing 2 lots of cables and talks of 'switch live' connection back to the boiler.

Can someone explain in laymans terms what it is i need to do extra that isn't already there (in terms of wiring)

I'm trying to get it done today if possible.


thanks

 

[TicklyT]

Just because the wires behind your existing 'stat are brown and blue or red and black doesn't mean they are live and neutral, it more likely means whoever installed that 'stat couldn't be bothered to sleeve them correctly.

You are more likely to find you have a live and a switched live, both of which should be sleeved brown or red.

Sometimes plumbers and others who should know better also use the earth wire of a cable as a live conductor There's a recent post on here concerning that.

A simple thermostat just requires two wires, live and switched live. It just connects the two together when it switches on, and breaks the connection when it switches off, just like a light switch.

Some include an 'anticipator', supposed to more accurately track room temperatures, and require live, neutral and switched live connections.

More complex ones may include programmer functions, and may need several wires, including Live, Neutral and one or more switched lives, according to the number of functions it is capable of performing.

What connections do you have at the boiler?
What were the connections to the old 'stat?
What connections are available on the new 'stat?

 

[mel7938]

the wires from the boiler are 1 red, 1 black & 1 yellow/green which go to a junction box (very similar to a light switch box) with a on / off switch on it. Into this junction box also comes the live feed from the main junction box and then someone has taken off a feed for the original fixed thermostat of 1 red & 1 black which are connected into the live & neutral ports of the original thermostat

In the new CM927 receiver unit there are 2 boxes, 1 with 1 neutral and 2 live ports then a second box with A, B & C in them. What do i need to do to wire this in now


thanks for your help