
15mm to 22mm = loss of flow rate? - MyBuilder
40234. Save yourself the cost and use 15mm because: - flow rate is improved through 22mm because the bends (and pipework) have a lower frictional resistance so unless it''s a very long, bendy run there will be no improvement. - 22mm pipework holds more water so on the hot side you''ll have more room temp water to run off before the hot comes through.