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hot water ok, heating not working - boiler not firing up

Posted: Sat Dec 12, 2009 1:50 pm
by neilhayes
Hi
Need some help on this one pls.
Got a conventional pumped heating system, with a Glow Worm 'Ultimate' boiler with a V4073A mid position Honeywell valve and honeywell programmer . Boiler regularly serviced.
Hot water for taps works fine (boiler fires up, pump runs).
But when Heating is called for, the boiler doesn't fire up, and pump don't run.
Room stat set correctly, got voltage across contacts and can see them make / break so seems fine. Also, have voltage to white and grey wires on V4073A valve - have used override lever on bottom of valve to make micro switches and have volts on orange wire that goes to the boiler.
That's about as far as i can go, getting a little stuck now.
Any help would be really appreciated.
Kind regards.
Neil H (UK)