In an earlier contribution to this discussion,
wrote:

I've had a new system boiler installed (Vaillent ecoTec 618) which is
wired to a Honeywell 6400 programmer. When ever i now turn on the hot
water the radiators get hot. Why is this? Has the programmer been
incorrectly wired? or is it that the diverter valve is stuck? Any help
will be much appreciated

I am assuming that the ecoTec 618 *isn't* a combi boiler - and that it is
supposed to provide *stored* hot water plus central heating. Is that right?

The 6400 is just a 2-channel time clock - so there must also be one or more
motorised valves - and probably a room and cylinder thermostat - making up
the overall control system. It would help to know whether you have a Y-Plan
(one 3-port valve) or S-Plan (two 2-port valves) system. See
http://content.honeywell.com/uk/homes/systems.htm for more details.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.