by marrtin »
Tue Oct 30, 2007 9:44 am
I can't see as there's any way to easily test for this. Ok, there will be a slight pressure difference between the flow and return, but just how you measure this I can't say.
If we assume that all the other rads are getting good and hot, then logically there can really only be three reasons why it's not getting hot. One of the feed pipes is blocked either with debris or it's kinked etc. A bad airlock or it's connected as you suggested.
If the rad is drained and disconnected, open the valve in turn at each end and allow the water to flow into a bowl this should expel any air and prove a good flow of water. If the all seems satisfactory, then the smart money is with your thoughts.