Thermostat calling for heat, heating not coming on......

25 Mar 2008
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United Kingdom
I've a Greenstar CDi boiler, about 18 months old.

The last few mornings I've woken to a cold house - the wireless thermostat is displaying a flame, so it is calling for heat but the heating is not coming on.

Hot water is working absolutely fine and gas supply is turned on.

The first morning I turned the thermostat off and then on, this seemed to kick start things and the heating was working when I got back from work.

This morning however, I turned the thermostat off and on, heating kicked in for 5 minutes then went off. Subsequent resets didn't get it working again either.

I've checked the pressure gauge on the boiler and this seems fine - 1.5 bar, the gas supply is definitely on, and there is no battery warning light on the thermostat.......

My boiler is in my garage, thermostat in the hall.

Any help / advice gratefully received!!
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Although the flame symbol appears, it doesn't always mean that the batteries are OK and the transmitter / receiver are talking to each other.
What make / model are they?
Is there a motorised zone valve fitted in the CH circuit?

If so it may be faulty and not opening to the point that the auxiliary switches that power the pump and boiler actually err... 'switch'.

If there is a manual lever on the valve push this across. If the boiler then fires then that is your problem.

New 'motorhead' may be required.
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I had a wired thermostat which used a battery. The battery symbol was not showing yet it failed. Changed battery A1 again. My daughter also had same problem. So I would change battery first.

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