UK trade guideElectrical Spares 6 min readUpdated 9 July 2026

How to Replace a Central Heating Pump (UK)

Fit a Grundfos UPS2 or Wilo Yonos PICO replacement heating pump. 6/1 valve isolation, orientation, air bleed.

GrundfosWilo

Isolate first

6/1 or 6/4 pump valves each side. Close both. Loosen the pump union nut — expect 200 mL of water. Ready a bowl and towel.

Fit

Orient pump shaft horizontal (never vertical up — air lock). Fit new gaskets. Wire live-neutral-earth via 3A fused spur. Open valves, bleed pump vent.

Frequently asked questions

What speed setting?
UPS2 auto-adaptive by default. Manual override — start at speed 3 for most 3-bed houses.
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