wow you testing my memory. Lets see now, Ideal Standard and Beeston are two that spring to mind.Nipples with a coating of linseed oil, pulled together with a pulling up bar and coaxed together with a pudlock. Burners supplied by British Oil and Gas (I know you will correct me if I have got that the wrong way round). Hospital rads were supplied up to a certain handling weight. If the rad came with extra sections, they were added using nipples with left and righthand threads with a paper washer between them and pulled together with a rad bar. Now gunge in F and E tank ( I don't pretend to know everything and so I will ask the question) I still have this thirst for knowledge. I was asking for input instead of reading tin labels. I am sure that different engineers would recommend different cures for the problem. Sorry I do not remember asking about air in the rad near the pump (No doubt you will refresh my memory). Commercial and domestic principals are the same but have different problems which only personal experience can solve. Over to you. ps not sure if Standard was added to Ideal at a later date.
