How to Replace a Grundfos Alpha2 25-40 (UK)
Fit a Grundfos Alpha2 25-40 pump on a UK heating or boosted DHW system. Face-to-face, orientation, bleed sequence.
Grundfos
The pump
Grundfos Alpha2 25-40 — confirm 130 mm or 180 mm face-to-face, and whether your system is single-phase 230 V or low-voltage.
Isolate
Turn off the boiler and 230 V spur. Close both pump gate valves. Have a shallow tray ready — approx 500 mL will spill.
Fit
Undo the pump unions, transfer the power lead terminating L/N/E in the correct order into the Grundfos Alpha2 25-40 terminal box. Orient the pump head so the shaft is horizontal. Open valves, bleed via the centre screw until water flows clear.
Set the Grundfos Alpha2 25-40 to the correct speed or auto-adapt curve per the OEM installer sheet.
Frequently asked questions
- Speed setting for Alpha2 25-40?
- Most modern UK homes: setting II on a fixed-speed Grundfos; auto-adapt on Grundfos A-rated pumps.
- Do I need to power-flush after fitting?
- Best practice — but at minimum add 500 mL Fernox F1 or Sentinel X100 and fit a magnetic filter.
- Is the Grundfos Alpha2 25-40 ErP compliant?
- Yes — all current UK-sold A-rated pumps meet the ErP <180 W directive.
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