In article .com,
TallJim wrote:
Unfortunatly the boiler only starts up when I manually open the Zone
Valves. The times control box doesn't seem to have any effect on the
system at all (although it does have power, and seems to be turning
itself on and off at the correct times).

Does this sound like a problem with the control box, as the boiler and
pump start up when I manually open the valves. Is the control box only
responisble for opening and closing the zone values automatically ?

If it's a standard S-Plan system with two motorised valves (one for
heating, one for DHW) then each valve has four connections. Two (L&N:
brown/blue) go to the motor and open the valve when power is applied. The
other two (grey/orange) go to a microswitch which closes when the valve
opens: one of these two wires should go to a permanent (except when
isolated) live, the other goes back to the boiler call for heat terminal.

If the system works correctly when you manually open either valve then
the boiler side of the wiring all sounds OK. This would then suggest that
power is not being delivered to the MVs when the programmer turns on and
you need to follow through the circuit to see what is happening. MV
motors do burn out, but the chances of both of yours failing together
would seem pretty remote.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
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