I am looking to replace the heating system in my bungalow. The plan is to use 28 mm copper into loft then down to 22 barrier pipe flow and return. Then off the 22mm to 10 mm down to radiators. My problem is I keep been told by others this is not a good practice. As the pipe been smaller is easier to block although I find this hard to believe has my last property had this system from new and never gave a problem. Any advice would be great thanks all.