I had a basin with separate hot water and cold water taps which functioned fine. Gravity fed system with hot water from cylinder and cold water from mains . With a bathroom upgrade, installed a mixer tap - Grohe Get Mono mixer tap (0.2 bar - 5bar) with flexi tails. The hot water flow is very low so the mixer tap does not work. Plumber thinks this is due to restricted size of hot water flexible metal hose but unable to change this to the size of the copper pipe. Looked at Bristan Capri but here again there are restricted size tails. I have tried to turn the mains water stop valve to a minimum setting and this seems to work a bit better but the overall water out of the mixer is reduced to a minimum to get the water warm. Is there any solution to this issue - any other mixer taps that would replicate the performance of individual taps ? any larger size flexi hoses (leads) which do not restrict flow. (Or means of replacing flexi pipe with copper pipe same size as supply pipe) Thanks for your help