I'm trying to find out which pipe is the flow and which is the return on a Myson Economist WM25/40
the hot water cylinder, pump, tanks etc have been removed, all I'm left with is the boiler and the two 22mm pipes coming out from the ceiling into the top of the boiler, so how can I tell which is which? the one on the left of the heat exchanger has a thin copper wire going into it is this a temp censor or something if so would it be sensing the returning heat or the flow heat.
Any help on this matter would be greatly appreciatedd