Hi. I was going to ask Rob how Vokera agents go about cleaning the recouperator on the Synergy e. Looked at one the other day, when opened up the FGA point, there seemed to be a fair bit of (I assume) ally oxide. It clearly needs a clean through but not sure of best way to proceed with it...
Hard to tell much from the picture.
Is it copper?
It may well be old 1 1/4" or 1 1/2" waste, in which case, the easiest solution may be to cut it back square and use a universal compression waste coupling to join onto it with a cap in tother end.
glass flow and returns could be handy for finding any blockages, you'd be able to see the cold feed blocked....
then again, if the pipework is glass, and the radiators don't suppose they'd corrode the same