I need to replace the gate-type NRV on the DHW circulation system because it bangs, repeatably, when some taps are turned on. I've been looking for a spring type, but I want a branded one because the no-name one that was on before fitting the current NRV buzzed when the circulation pump was running. The Kuterlite K424 fits the requirements but Wolseley want £65.51 when other suppliers are around £17, which still seems a lot compared to the cheapies, but ...