How to wire Horstmann C-Stat 11-ZW wireless programmer to Worcester 24CDi?

[trionic]

Totally not your bad. In the first post, I did write "I did measure voltages at the programmer and boiler ends but the results didn't help my understanding." and I should have expanded on that because I did not measure 240v across any of the terminals.

So. Is this what we have:

240v supply live from isolation switch to L on new prog room stat
240v supply neutral from isolation switch to N on new prog room stat
Black (sleeved red) conductor on the white flex to 4 on new prog room stat
Remove link wire between L and terminal 2 (common)

If I have that correct (and I think I don't) then, on the white flex we have blue and brown conductors which are now unused (but have voltage on them) and would be capped-off.

 

[CBW]

Pretty much, but either leave the link for live and common in, or use the Live in which on the C7 was the red wire. The yellow wire is your call.

 

[trionic]

Well the yellow wire is on the T&E to the C7 and thus de-energised and safe anyway.

I'll have a crack at thos again tomorrow.

 

[CBW]

Because the switch live out would be provided from the boiler, which is why you can leave the link in and just use the call for heat wire.

 

[trionic]

Given that the boiler-provided switching voltage is 18v and not 240v, then I think that should be used.

So:

240v supply live from isolation switch to L on C-Stat
240v supply neutral from isolation switch to N on C-Stat
Remove link wire between L and terminal 2 (common)
Brown conductor on the white flex to 2 on C-Stat
Black (sleeved red) conductor on the white flex to 4 (call for heat) on C-Stat
Blue conductor on the white flex to N on C-Stat
Connect the earths

So the receiver will be powered by 240v but the boiler switching (call for heat) voltage will be 18v, as before with the C7.

 

[trionic]

Just finished the job. I connected everything as above and it all works perfectly.

The Horstmann C-Stat is a nice product. The software's well designed and the user interface is intuitive. The Z-Wave wireless connection is reliable and the wireless programmer picks up a signal anywhere in the house (and down the garden too!). Only gripe is that the screen on the programmer's slightly crooked but I suppose if I took the thing apart I could tweak it over a touch (only about 0.5mm). The Horstmann kit was expensive at £93 inc VAT but it looks much nicet than the competition and I knew that the C7 was well made and reliable so I bought the same brand. I'd recommend both the C7 and the C-Stat.

Thanks for all the help received.

Now, who wants to buy a used very good condition C7?!