No Central Heating After Draining Down

A friend of mine who is a recently qualified plumber drained a system to connect an extra radiator onto it. After refilling the system everything appeared to be working okay but the next day the central heating was not working. He asked me to go and have a look because he was unsure what the problem was and didn't know for certain if the motorised valve was working.

When I arrived the central heating was set to be on and the pump was running. The valve was a Sunvic SDMV230 valve. I removed the motorised valve head and switched between the heating and hot water to make sure the valve was moving, and the that the spindle was in the central heating position which it was.

The pipework was not set out as it should be to remove air efficiently from the system and their was a lot of air trapped in the airing cupboard pipework. There was an air vent in the airing cupboard which I opened regularly to bleed off air. I also opened the screw in the centre of the pump to release any air in the pump. After releasing as much air as I could from the airing cupboard I walked around the radiators. The three radiators upstairs were hot but there was not much heat in the three downstairs radiators.

I turned off the radiators upstairs and one of the radiators downstairs got hot so I turned this off also. Then both the other radiators started to get hot and there was some gurgling. I left these radiators running for five minutes to make sure all the pipework was clear of air before turning on the rest of the radiators. I left the central heating running for some time to ensure that the central heating was working correctly and that all the radiators were heating equally.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.