I have a Potterton Promax HE plus boiler in a pressured system - i.e. red pressure cylinder in airing cupboard - with Grundfos pump and hot water cylinder. Had a few problems when we first moved in with boiler failing and needing to be reset - boiler panel lights showed a flow issue. Called a plumber in who changed the flow switch and the leaking inlet manifold - all good for a few months.
Now it appears that the boiler is firing up first thing when the controller switches it on, but then it cuts out after a while and never comes back on. When we come down stairs it is freezing cold, I can hear the pump still running in the airing cupboard but the boiler hasn't kicked back in. When I turn the thermostat down from 20` I can hear it 'click' at about 13` or 14` and I can hear the pump stop. I leave it for about 30 seconds then turn it back up to 20` and after a few seconds the boiler fires up. It then continues to run all day without a problem, although it does cut in and out for short periods sometimes.
Does anyone have any ideas what might be happening or what I should check please?
