Room thermostat help please?

[shentodj]

I have read 3 or 4 other Thermostat threads but can't see all the answers I'm looking for.

I am looking to replace and old rotary Honeywell thermostat with a fancy new programable one (as has been discussed in other threads).

My current thermostat has 4 wires:
1) Yellow/Green = not connected.
2) Red
3) Yellow
4) Blue

I think I can infer from the other threads that they must be:
1) Earth
2) Switched Live
3) Neutral
4) Call for Heat
QUESTION1: Can someone please confirm this is correct?
QUESTION2: It has been mentioned that I need to "isolate the Neutral" - does this mean wrap lots of insulating tape around it and connect it to nothing?
QUESTION3: I assume I need to switch off the power (cct breaker) before messing?

Thanks in advance.
Regards,
Shentodj

[Gingerbread Man]

I'm no good at sparkying, but;

Yellow/ green - earth
Blue - Neutral
Red - live
Yellow - call

[Smiler.]

Definitely isolate all circuitry & check its all isolated before touching.

The wiring you suggest is correct.

But be careful, I have seen many weird variations on the correct wiring of these in the past so always best to verify as much as possible.

If you have a wiring centre & can find it (buff coloured box about 8 x 6), it will have a wiring diagram on the inside to confirm should be wired into the terminal strip.

[andy43]

shentodj said:

QUESTION1: Can someone please confirm this is correct? Buy a tester screwdriver - plumbers can use whatever colour coding suits them.
QUESTION2: It has been mentioned that I need to "isolate the Neutral" - does this mean wrap lots of insulating tape around it and connect it to nothing? Yes.
QUESTION3: I assume I need to switch off the power (cct breaker) before messing? YES!! But leave cover off, switch elecy back on and test with tester screwdriver to see which is live. Then turn off to replace stat.
Tbh, if you're asking this, an electrician may be a safer option, no offence intended

[Arthur Jackson]

Gingerbread Man said:

Yellow/ green - earth
Blue - Neutral
Red - live
Yellow - call

This probably correct, but as Smiler says you need to be absolutely sure. I'd disconnect the neutral at the junction box rather than at the 'Stat. Then use the red and yellow as switch wires.

[Gingerbread Man]

I'd isolate the wire by terminating it into a chocolate box connector as opposed to tape.

[Simpo Two]

Gingerbread Man said:

terminating it into a chocolate *box* connector

Easily identified as they have pretty pictures of cottages and kittens on them!

[jason s4]

I have never ever seen a wiring centre that is wired as per the instructions on the lid.

And that is assuming a proper one has been used, as many just use a box and lid.

Dont go poking around in whatever you have as there are a LOT of connections in there, and if one pulls out you are fked as you have no idea where it would come from.

Get a sparky in.

In could be cheaper in the long run.

And not all room stats are the same. Some programmable stats will need to have the correct wires in the correct terminals.

They are not just make and break.

[Ricky_M]

jason s4 said:

I have never ever seen a wiring centre that is wired as per the instructions on the lid.

I'm guilty of this! First thing I do is remove the links, scribble over the instructions and wire it my way! Uses 7 blocks instead of 16!

So never assume anything! If you are confident with a multimeter, it'll be a piece of cake.

[jason s4]

Ricky_M said:

I'm guilty of this!

Me too