help with replacing old central heating timer please

[alanmzifa]

Hi, I need a bit of help replacing a central heating timer. The boiler is oil and single circuit, the pipework heating the radiators and hot water tank simultaneously.

The existing timer is mechanical and the replacement is a Drayton Tempus 1 electronic timer for systems with 1 heating circuit.
My problem stems from the different connections on the old and new timers.

The old one has just 3 connections on a connection block (numbered 1,2,3), the new one six. As the old timer hasn't got one of the "new" standard 6 pin backplates I can't work out what goes where.

The wires I can see in the wall box and where they are connected to the old timer are as follows...

Thick black cable (presuming to boiler), 4 wires
black - connected to 3
red - connected to 1 (live only when timer switched to "on")
green - earthed
blue - not connected

2 grey cables, 3 core (seem to be on same circuit as kitchen light wiring),
black - connected to 3
red - connected to 2
green - earthed
black - connected to to 3
red - connected to 2
green - earthed

So, in other words there are 3 black wires connected to 3, 2 red wires connected to 2 and one red wire connected to1. The red wires/terminal on 2 is permanently live, the red wire/ terminal on 1 is only live when the boiler has switched on.


Thanks in advance for your help.

 

[Taylortwocities]

As far as I can see, and from the instructions for the clock:

The red that is on 1 on the old timer goes to terminal 3 on the new one

All the other reds go on to L

All the blacks go on N

Put a link between L and 1

That should do it.

 

[alanmzifa]

Thanks for the reply Taylortwocities.

When you say "put a link between L and 1" I presume you mean just join these two terminals with a short piece of suitable wire, yes?

 

[Taylortwocities]

Yes