Changing room thermostat; help with wiring needed please

[KnightWhoSaysNi]

My old thermostat is a mechanical one and looks like this:

I'm replacing it with a digital one, here is the wiring diagram on it:

From what I reckon, the old one has:
1 = permanent live
3 = switched live
4 = neutral

Am I correct in thinking that on the new one it's:
1 = permanent live
2 = switched live
3 = neutral
?

 

[ericmark]

Original has a neutral which is not required with new one which can be used for heating or cooling so either N/O (normally open) or N/C (normally closed) is used depending on if the device heats or cools. With mine I know no battery and there is no heat so the heat must be N/O when it wants heat they must close but it is rather a silly marking CH and AC would be far better.

 

[Midas Man]

Red number 2 and yellow number 3 on yer new stat.

Blue not needed so make the end safe and tuck in box.

 

[KnightWhoSaysNi]

Cheers.

As for safety, is it sufficient to just isolate electric supply to the boiler to carry out the work?

Red number 2 and yellow number 3 on yer new stat.

Blue not needed so make the end safe and tuck in box.

I've done that and it seems to be working in the opposite direction. When it's set to a low temp, the fire icon is off but the heating comes on. When I set it to a high temp, the fire icon comes on but the heating is off.
Looks like it's working in cooling mode?

Maybe I should use the blue wire, or connect the yellow one to 1 instead of 3?

 

[Taylortwocities]

Maybe I should use the blue wire

NO WAY!!. There will be a bang and you'll need a new stat/programmer.

Yes, yellow should be on 1

 

[KnightWhoSaysNi]

I've put yellow on 1 and it's working ok now.