The cold water supply to my electric shower comes from the rising main in the bathroom ,
The vertical mains pipe is in 22mm then goes under the floor to the bath in 22mm as well then a vertical 22mm feed goes to the shower via a full bore valve like this .
If the part after the valve was all in 15mm ( apart from a short piece to reduce it to 15mm) would that make any difference to either the pressure or flow rate .?
There has been an issue with the shower cycling but it happened at the weekend but I havent pinned down the reason . I can understand intermittent problems with neighbours ( it's an 8 flatted property) if they are running cold water for baths,dishes,toilets at the same time as the shower is being used ( everyone has combi boilers if that is relevant) but on Saturday I put my ear to the p/board behind which is the rising main and I could hear it running and it seemed to go on for ages which confused me a bit.
Stuart