Home › How-to & fixes › What size pipe do radiators use
AnswerWhat size pipe do radiators use?
Most UK domestic radiators run on 15mm copper pipe, sometimes reducing to 10mm on the final run or 22mm on the main flow for larger systems.
In more detail
Check your existing pipe before buying valves so the connections match.
2026 figures · BTU uses standard UK heat-loss methodology; running costs use the Ofgem price cap · always confirm with a professional.