Does anyone know where you can find one these surge expansion vessels as shown in the "Low Head Installation" diagram?
Bit of 42 copper + 2 x 42-22 reducers. Job done.
OK, so where do I get 42mm copper and 42-22 reducers? Best I've found is 35mm at plumbase (and I have to buy 3m!).
Update: I've found some 42mm 1.5m, at jtm plumbing online but I think I now have a better solution.