Domestic issue ;-)

[GC888]

OK so have a intangible issue with a domestic CH system.

CH & HW controlled by timer, 3 way motorised valve, room and cylinder thermostats.

The boiler works fine and efficiently heats the hot water on the cylinder thermostat calling.

But the central heating will not work.

Checked the pump - working fine (when triggered by cylinder stat)
Checked room stat - working fine (triggers motorised valve - lights and movement) but does not trigger pump/boiler
Checked cylinder stat - working fine (triggers motorised valve - lights and movement)
Checked timer - powers up lights on (exchanged unit with a spare all good)
Checked all cables (disconnected continuity fine)

Any suggestions or clarifying questions where to test next welcome?

Thanks

G

 

[codcutter]

Replace power head on 3 port valve (some will say change synchron motor)