One-pipe, two-pipe, and fully pumped S-plan and Y-plan arrangements.
Under C&G Unit 206, domestic central heating systems distribute heat from a boiler to emitters (radiators) using various layouts:
- One-Pipe System: Radiators are connected in a single loop. Cooler water from each radiator returns to the same pipe, meaning radiators downstream run progressively cooler.
- Two-Pipe System: Separate flow and return pipes. Each radiator receives hot water directly from the flow pipe and returns cooler water to the return pipe, giving uniform radiator temperatures.
- Fully Pumped Systems (Y-Plan / S-Plan): Use motorised valves to control heating and hot water separately. Y-Plan uses a single 3-port mid-position valve; S-Plan uses two (or more) 2-port zone valves.
*Original revision guidance; confirm against Approved Document L and standard domestic schemes.*