Replacing Central Heating Timer

[Steve56]

Hi,

Was looking to replace my central heating timer with a TimeGuard NTT04. Had a look yesterday and the wiring is different than my old timer.

The new timer has 4 connections - L, N, S In, S out.

Wiring diagram -
230V 50Hz Mains Supply:
Live (Brown or Red) to L
Fit a ‘Link’ or ‘Bridge’ between L & S IN
Neutral (Blue or Black) to N

Load:
Switch Live (Brown or Red) to S OUT Neutral (Blue or Black) to N
Full manual here: http://www.timeguard.com/media/2566/NTT03_NTT04_Instructs_120x60_issue3.pdf

From my old timer I have:
2 x Red
1 x Black
1 x Blue
1 Yellow

Image attached.

The S In and S Out has confused me. Any help on how I should wire this would be appreciated.

Thanks,
S

 

[Leesparkykent]

Hi,

Was looking to replace my central heating timer with a TimeGuard NTT04. Had a look yesterday and the wiring is different than my old timer.

The new timer has 4 connections - L, N, S In, S out.

Wiring diagram -
230V 50Hz Mains Supply:
Live (Brown or Red) to L
Fit a ‘Link’ or ‘Bridge’ between L & S IN
Neutral (Blue or Black) to N

Load:
Switch Live (Brown or Red) to S OUT Neutral (Blue or Black) to N
Full manual here: http://www.timeguard.com/media/2566/NTT03_NTT04_Instructs_120x60_issue3.pdf

From my old timer I have:
2 x Red
1 x Black
1 x Blue
1 Yellow

Image attached.

The S In and S Out has confused me. Any help on how I should wire this would be appreciated.

Thanks,
S

View attachment 36367

What was your old timer and do you know what each core was connected to on the old timer?

 

[Steve56]

What was your old timer and do you know what each core was connected to on the old timer?

The old one was an APT timer and unsure what each core was connected to on it

 

[Leesparkykent]

The old one was an APT timer and unsure what each core was connected to on it

Your going to need an electrician or a heating engineer I'm afraid.

 

[Andy5678]

Yup those wires need testing and traced back to the boiler to see what one does what. If you took a pic of the old timer it would be a lot easier