Central heating controller fitting HELP!

[Scott2012]

I have tried to replace a broken Drayton Tempus one controller with a centaur plus C27. The old one has never worked. Previous owner said a leak for the boiler had killed it. It was only ever in holiday mode. I got around to buying the new one and was an easy swap with commonly back plate. It is working but does not seem to control the boiler at all (boiler is a Vaillant Combi about 8 years old). I'm wondering if someone changed the wiring. On the back plate there are two blue into N terminal, two brown into L terminal, one black into 1 terminal, one black into 3 terminal and two black wires crimped together. What am I missing? Hope you can help.

 

[D_Hailsham]

I got around to buying the new one and was an easy swap with common back plate.

The plate may be common, but that's all: the terminals are not common.

On the back plate there are two blue into N terminal, two brown into L terminal, one black into 1 terminal, one black into 3 terminal and two black wires crimped together.

Was there a link between terminals L and 1 on the backplate? If there was NO link, the Centaur C27 is not a suitable replacement: you need a programmer with volt free connections.

 

[Scott2012]

Thanks for that. I cannot see any connections between L and 1. Guess I'm shopping for another controller. Any recommendations for a cheap volt free one? Is there a way of finding out which wire is which ready for putting the new one in?

 

[Scott2012]

Thanks for that. I cannot see any connections between L and 1. Guess I'm shopping for another controller. Any recommendations for a cheap volt free one? Is there a way of finding out which wire is which ready for putting the new one in?

 

[D_Hailsham]

Thanks for that. I cannot see any connections between L and 1. Guess I'm shopping for another controller. Any recommendations for a cheap volt free one?

The C27 is a two channel programmer, as you have a combi boiler you only need a single channel one, which is what the Tempus 7 is.

Suitable replacements are:

24 hr
CentaurPlus C11
Drayton LP111
Honeywell ST9100A

7 Day
CentaurPlus C17
Drayton LP711
Honeywell ST9100C

There are others, but I can't list then all. Just make sure that it is a single channel with volt-free contacts.

As for wiring, L and N are obvious. The wire in terminal 1 of the Tempus 7 has to go in the COM terminal of the new timer; and the wire in Tempus 7 terminal 3 has to go in the ON terminal of the new timer.

Read Installation Instructions!

The pair of black wires crimped together should be put into a terminal block or wrapped in insulating tape to make them safe.