Bear with me as this might sound a bit mental!   Current downstairs heating is a 50 year old 3/4" nominal bore system.   New bathroom refurb has x1 UFH loop in the floor and a second loop purely for a towel rad.   I don't really want to connect a manifold to the old single pipe system and get it and the new loops crudded up. Now for the mad bit...   Thinking that as I've a spare copper cylinder I could divert the single pipe CH through the coil of the cyli