Great, thanks. I have just ordered from a plumbing website. I noticed allot of the bends were either 12 or 14mm, I have gone with 14mm, since it is near 9/16. Keen to get as much hot water into the matrix, since the aperature on the heater valve looks tiny. Thanks again for posting. I am sure...

That's what I was thinking, I am just not that clear on how wide a diameter to go on any brass where - I am assuming the more hot water I can get into the matrix the better. If anyone has a view, I would be grateful.

Many thanks for this Webley - after having had a cold winter in the landy, I am going to swap mine out. What diameter did you go with and was the elbow male or female?