Hi I recently has to move some rad pipes in my bathroom. I drained down my CH system (open vent gravity system with Baxi bermuda 551 back boiler. When it came to refilling the system I bled all the rads as it filled up and it seemed to be working fine. I also put some central heating cleaner in the header tank. About 45 mins later there was a loud sort of gurgling noise in the loft which went on for about 30 secs. Since then the rads wont warm up and the boiler wont fire up. i've tried bleeding the rads again but there is no air in them. The pipes to the pump seem to be getting hot on both sides of the pump. Any ideas please?