Initially both central heating AND hot water stopped working completely. Through various small fixes, I’ve got the hot water back working, and a small amount of central heating. The system is: Indirect open vented F and E gravity system. Back boiler behind fireplace. Two tanks in loft (header and cold water). Hot water cylinder in airing cupboard, no immersion. 3-way motorised valve. Honeywell controls. Grundfos water pump. 9 Radiators. Things I’ve tried: Bled radiators, bled pump, bled air vents, opened all radiator valves fully, turned thermostats up high, checked header tank is full. After doing all this, the hot water started working again. Upstairs, 1 radiator now works fully and the other 3 are showing signs of heat. Downstairs, nothing from any of the 5 radiators. Any ideas/diy fixes/feedback will be much appreciated! Thanks.