Vaillant/Heatmiser wiring problem

22 Jun 2011
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United Kingdom
I have a Vaillant ecoTEC plus 630 system boiler supplying 4 central heating zones (3 radiator and one wet underfloor) and one unvented hot water cylinder. The system is controlled by a Heatmiser wiring centre linked wirelessly to 4 room thermostats/timers.

When the heating is on and the hot water timer is on too, hot water is produced. However, when the heating is off (as has been the case over the summer), there is no hot water.

I have checked the zone valve for the boiler and it is working (and as I understand it, if it wasn't working, there would be no hot water even with the heating on because there would be no way for hot water to flow into the cylinder). The timer for the hot water is also communicating correctly with the wiring centre. The wiring in the wiring centre has also been connected according to the instructions.

I therefore think that the problem lies with the wiring centre not being connected to the boiler correctly, such that there is no call for heat when the hot water valve operates independently of the heating valves, and it is only the heating valves that operate the call for heat on the boiler.

Is there a simple fix for this? I have not yet taken the boiler apart to find the connections made by the heating installer, but from the instruction manual it seems as though there are a lot of terminals.
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I meant take the casing off to find the wiring terminals to see if there's an issue with how the wiring centre has been connected. I wasn't planning to strip it down and throw parts all over the kitchen floor.
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OK. Fine. So what is the likely source of the problem? Why would there be a call for heat from the central heating zone valves but not from the hot water cylinder valve, when both are wired into the wiring centre according to the instructions?
Have you checked for 240 volt @ orange core of HW zone valve when a call for heat (end switch)?
Possibly HW zone valve has been manually opened due to faulty motor?
Could be a number of issues which would take all of 5 minutes to diagnose if you know what you're doing.
For what reason would you want to remove boiler front cover?
Hey Dan , I'm not sure that the OP understands you when you say the boiler is working..:ROFLMAO:;)
if the boiler has been working OP why are you considering the wiring is wrong ( as dan is saying ) ?? think you better get someone in before opening that boiler up :cautious:

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