How to Wire a Y-Plan Heating System (UK)
Complete Y-plan wiring centre diagram: boiler, pump, 3-port valve, cylinder stat, room stat, programmer.
HoneywellDraytonDanfoss
Y-plan components
- Boiler with volt-free contacts.
- 3-port mid-position valve (Honeywell V4073A).
- Central heating pump.
- Cylinder stat (Honeywell L641A).
- Room stat (any).
- Programmer/timer (Honeywell ST9400C or Drayton LP722).
Wiring centre
10-way wiring centre with permanent live/neutral, switched live from programmer, HW demand, CH demand, and the 3-port valve orange/grey/white cores.
Frequently asked questions
- Can I convert Y-plan to S-plan?
- Yes — replace the 3-port with two 2-port valves (V4043H) and rewire. Better zoning and reliability.
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