I have just fitted a rad into a conservatory and both that and the rad I have fed from are no longer working and I'm suspecting that there may be an airlock. It is a two storey house and the rads upstairs are getting hot as are some of those downstairs. The rad that I had fed from had feeds coming from upstairs and this did not have a seperate draincock so I had to drain the messy way (by undoing the rad valves and have now put one in to the rad that I fitted that will service both rads. But because these rads are quite a bit lower than the flow and return pipes I think this is where the airlock is. I have tried draining water for about 15-20 mins to pull down some hot water but it only partially worked and only one pipe got warm (not hot). I have searched and found that you can blast cold water from your kitchen tap to clear airlocks in hot water systems, but can the same method be used for central heating systems with maybe putting a check valve in the attachment hose to stop contamination? The airlock I suspect is under the floor upstairs so it will be a major job if I have to get physical access to it! Any other suggestions very much welcome. Many thanks for your attention!