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
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If it's a Y-Plan, there will be a single 3-port valve which has 3 positions - HW only, CH only or both together (mid-position).
For whatever reason, your valve appears to be in the mid position when it should be in the HW-only position. This could be faulty wiring - or the valve could be sticking and not letting the return spring move it to the HW position. It could *even* be incorrect plumbing - assuming this is a brand new system which has *never* worked properly.
You need to get the installer back to sort it.
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