Central heating not coming on but still getting hot water?

[PerspectiveUrgentlyRequired]

I thought it was a bit chillier today so decided to put the heating on for the 1st time in months. Nothing. Checked the hot water - still running in both the bathroom and kitchen. None of the radiators have got a bit of heat in them at all. Can't tell if it's the control switch, the radiators or the boiler. The only thing that made the boiler make it's usual 'groan' when starting up was to press the eco button off then on again, but still no heat in the radiators. The boiler is a worcester, and has a small green light flashing above the override button. Can't find anything in the manual that tells me what that means, if anything. The light could have been flashing before this happened, I've just never noticed it before.

Any ideas? It's due a service soon, now I'm worried it's going to cost me a fortune 'cos something is broke.

Hi all, I have a problem with my combi boiler, the heating only comes on sometimes, you can hear it trying to fire up and run but then seems to time out and give up, the hot water is ok but takes sometime to heat up which it never did before. Pressure is ok and there's no air in the radiator. This seems to be a intermittent problem. Anyone come across this.
Many thanks

Because your problem is different to the one this thread is about, I recommend you start a new one.

All the background on this one will be incorrect for you.

Hi just wanted to add my thanks for this thread as I had exactly the same problem, flashing green light, nothing happening with heating, changed the batteries in the thermostat and have heating!! Thank you again power of MN!

This little video might help. It is a good idea to flick your central heating on during the summer just to stop that diverter valve in the boiler sticking. 30 seconds once a fortnight it enough to keep it moving. Often it is due to the dirt in the central heating water.