Help replacing old thermostat with new

[Noisy76]

Hi, I have a new thermostat for our central heating which I'd like to install, however I'd like some guidance on wiring it in.

I have some experience in electrical work, and have taken precautions to isolate the wiring, and checked with my multimeter, so everything is safe to work with.

This is the old thermostat and wiring.

This is the new one, and instructions. I assume the existing live and neutral go to pins 7 and 8 as shown, but then does the control wire go to one of 3 and 4?

Thanks for your time.

 

[333rocky333]

i woild say yellow goes to 6, but wait for a second opinion
To use 3/4 you would need to link one of them to 7

 

[EFLImpudence]

This is the new one, and instructions. I assume the existing live and neutral go to pins 7 and 8 as shown,

Yes.

but then does the control wire go to one of 3 and 4?

No, it goes to 6

 

[Noisy76]

Thanks. I had assumed 5 and 6 were for hot water systems as it says on the top of the page "Wiring Diagram Water"

 

[EFLImpudence]

It's just a switch. The other diagram just says 'boiler'.
There are no water connections on the old thermostat. Do you have a combi boiler?

Do you mean that the new thermostat has separate settings for hot water and central heating?

If so, then you can use 4 for Yellow but you will need a link wire from L to 3.

 

[EFLImpudence]

I think the 'water' reference is a confusion.

This is what you should be looking at:

You don't need 8 for the Neutral to the valve.

 

[EFLImpudence]

Rocky seems to be beating me to it. I didn't see your replies.

Sorry Rocky.

 

[Noisy76]

Thanks. so just to clarify, Live and Neutral to 7 and 8, and control (yellow wire to 6)? I'm a bit confused now!

 

[EFLImpudence]

Thanks. so just to clarify, Live and Neutral to 7 and 8, and control (yellow wire to 6)? I'm a bit confused now!

Yes.

It just sends 240V to the boiler as did your old thermostat.

3 & 4 would be used for 12V or 24V boilers.

If you have a combi boiler you won't have a valve. As I said the instructions are confusing.

 

[333rocky333]

Rocky seems to be beating me to it. I didn't see your replies.

Sorry Rocky.

I wasnt too sure, maybe a picture of the front may help

Is it one of these

 

[Noisy76]

I wasnt too sure, maybe a picture of the front may help

Is it one of these

Yes

 

[Noisy76]

Thanks all, it's working perfectly

 

[EFLImpudence]