Hi! I’m wondering if anyone can help. Iv got two main questions. It might be worth me doing two different threads but I’ll try here first. first question. what size mm pipes do I need for the sink, shower, bath etc around the house. Will 15mm be sufficient or should it be 22mm main then spur off to 15mm? second question. I’m changing from a one pipe system to a two pipe flow and return system. I have a combi boiler and I’m just wondering. firstly. Can I keep the same boiler? And secondly should I run this flow and return in 22mm with 15mm spur off to each radiator? ALSO I have 4 radiators upstairs and 2 (currently) downstairs as I’m planning on having UFH for the rest. But if this doesn’t happen then I will have 8 downstairs. is it ok for the heating to run upstairs first and then have drops into each downstairs room rather than running two seperate(ish) circuits as a lot of the upstairs radiators are above the downstairs ones. thanks for any help sorry if these seem stupid questions but appreciate it either way.