New Horstmann c17 wiring installation

[Nickm42]

Hi,
i just bought a new Horstmann c17 programmer, which I tried to install but doesn't seem to be working correctly. My original set up was a combi boiler with a room thermostat connected by a Live/neutral flex (earth wasn't connected).

the terminals on the c17 programmer are N L 1 2 3 4.

When i installed the c17, I split the wire to the thermostat and fed the wire from the boiler to the programmer, Live wire to L terminal and Neutral wire to N terminal. With the wire from the thermostat I connected Live to terminal 4 and Neutral to terminal N on the programmer. I also wired L to terminal 2 on the programmer. I didn't touch anything on the boiler.

The programmer is working although only once I connected L and terminal 2, but I can set it and the system light is on. However the thermostat isn't kicking in when I set the temperature to high and the boiler is off. Not sure what the problem is.

Any help would be gratefully apppreciated.

many thanks,

Nick Maskell

 

[jackthom]

Sorry but that's all way off course unless I've misunderstood your post.

The thermostat control wire you have broken into is not meant to supply mains power to your programmer .

Can you post photos of the wiring in the room thermostat and the new programmer?

 

[Nickm42]

Hi jack, thanks for your reply, here are the photos of the wiring,

The wire going through the wall is connected to the thermostat, the other one is from the boiler.

I saw some wiring diagrams showing that the programmer needed it's own direct power supply and others showing connection only to the boiler, maybe the connections on the boiler need to be changed. Anyway I will wait for your advice. Hopefully I won't need to move the programmer near to a power supply.

Thanks for your help,

Nick

 

[jackthom]

The programmer definitely needs it's own new power supply cable to Live and Neutral terminals. This should come from the same supply point the boiler is wired to.

You might want to safely restore the old thermostat wiring as it was, just so you still have some control of the heating in the meantime.

Then when you have the programmer properly wired with it's new supply, you can break into the thermostat wires again.....
One of the Browns will go to terminal 2 on the programmer and the other brown to terminal 4.
The 2 blues should just be connected together and insulated from all other wiring in the programmer.

 

[Nickm42]

Hi jack, I connected it all up and it's working perfectly. Very happy.
Thanks alot for your help.
Best regards,
Nick