In article ,
geoff wrote:
In message , "Dave Plowman (News)"
writes
I replaced my trusty of old basic electric Potterton Kingfisher with a
Vitodens 200 system boiler some months ago. And it works just fine.

However, I miss having the external programmer of old - if I wish to
switch things off when going away etc it means going to the boiler
itself. Viessmann reckon the way round this is to use an extra external
controller - using the room stat circuit - and leave the internal one
set to constant. Which isn't really what I want. Apart from the
unnecessary cost.

The integral controller has a four pin plug for everything - so I'm
assuming DC

why DC ?

It's basically just a PCB with surface mount components on it - no signs
of mains transformers or relays etc anywhere.

The Saunier Duval programmer is 24vdc powered, but almost every other
one I've encountered is mains powered

I've not investigated fully but I'd guess it controls external relays etc
via an external interface.

I have a spare programmer as I bought the external temperature
compensation kit which uses a different one. Ie, different electronics etc
but 'physically' the same. So I can trace what the four pin plug on the
PCB is wired to at leisure

--
*If Barbie is so popular, why do you have to buy her friends? *

Dave Plowman London SW
To e-mail, change noise into sound.