Hi there Thanks in advance for people’s help - it’s much appreciated. Had a small accident today draining the central heating at my new house, which I recently bought for my wife and 1 month old baby. It has a combi boiler. If someone could help me understand my idiocy that’d be grand. So, today I had planned to remove six radiators across three floors, leaving five in place. I thought I’d successfully drained the system. Main water off; boiler off; drain valve opened; water came out; opened rad valves starting at top floor then first floor then ground. Left it for hours. I then removed a couple of rads from top and first floor, fitting SF stops. That was all fine. Then I got to the bathroom, where the boiler is, which is on a mezzanine level between the ground and first floors, and set about removing the rad there. As soon as started cutting the pipe I realised I was in trouble - water started gushing out as I cut the pipe. I froze for a sec and then decided to finish the cut and pushed the speed fit stops on the gushing pipe, which stopped it after a small puddle was created on the floor. The pipe gushing was the feed from the boiler. So now I understand that the drain didn’t work properly - there’s still water in the system, around the boiler. The valves of the downstairs rads are open, so presumably rhere must be some airlock in there somehow? Is that right? If so what should I do? Or am I complete missing my marbles? Thanks in advance Gus
Where is the drain cock ,ground floor or elsewhere ? To fully drain the rads and pipework above ,you need to use the lowest drain point on the system ,and VENT all upper rads with the air bleed valve on them. That allows air in ,and breaks any vaccum. That won't necessarily drain ALL ground floor rads either.
Probably no help whatsoever, but whenever I've drained my system I turn the water off to the house first, connect hose to lowest rad drain cock stick hose out the window, then open the bleed valve in highest rad.
I’m assuming it is trapped water caused by somehwere I didn’t vent. Will try again tomorrow. Thanks for help
Always wise to open the rad valve on the pipe leading from/ to it before cutting into the pipe. Was the pipe horizontal or vertical where the cut was made ?
Horizontal, just below the radiator which was 100% open. The system flows down from the boiler into the floor, and then down and up around the house. I think some water between the boiler and the floor has simply been trapped. I’m going to drain the pipe tomorrow and let it all flow out
Why? If you had used spanner’s, you could easily put the radiators back without having to redo the pipework. Adding just a short length of pipe will probably look a mess,