I've just had to replace a very old pump on my CH system (30 y.o. gas boiler still going strong, pump feed to HW cylinder and rads via zone valve)Was fine for 1st few days, but now emits loud bangs in the pipes when it starts up. Ok once it gets going. Pump is not supported on wall, just in middle of length of vertical pipe near boiler (4 storey house)Any ideas please or is it ok to do this?
