How to Replace a Motorised Zone Valve (UK)
Fit a 22 mm or 28 mm 2-port zone valve on Y-plan or S-plan heating systems. Honeywell V4043H, Drayton ZA5/ZA6.
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Actuator vs body
Body wears rarely — actuator (motor + synchro switch) is 90 % of failures. Swap actuator only where possible — cheaper and no draining.
Fit
Isolate boiler and pump electrics. Actuator: undo 4 screws, unclip cable. New actuator clips on. Wiring at wiring centre — orange/grey/blue as per V4043.
Frequently asked questions
- Y-plan or S-plan?
- Y-plan = one 3-port valve (mid-position). S-plan = two 2-port valves (one CH, one HW). S-plan more reliable long-term.
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