In the process of fitting new 140ltr hot water cylinder and 50 gallon cold storage tank. The reason I'm doing this is to provide ample hot water for my thermostatic power shower via a 1.5bar pump. The pump instructions say ideally a 28mm cold feed pipe to the hot water cylinder should be used but 22mm will suffice.Obviously I would like to use 28mm as instruction say but is the extra expense of using 28mm instead of 22mm worth it. Also can anyone recommend someone who sells 28mm fittings as screwfix don't seam to sell all the fitting I require.