UK trade guideElectrical Spares 5 min readUpdated 9 July 2026

How to Replace a Grundfos 15-50 Pump (UK)

Direct replacement of legacy Grundfos Selectric 15-50 with modern UPS2 15-50/60. Wiring and speed setting.

Grundfos

Direct swap

UPS2 15-50/60 replaces old Selectric 15-50 with identical dimensions and 6/1 valve fit. No pipework changes.

Speed

3-speed manual — start speed 3. If rads take >10 min to warm, uprate to speed 4. For an ErP-A pump upgrade, fit Grundfos Alpha2 (auto-adapt).

Frequently asked questions

Is the Alpha2 worth the extra vs UPS2?
Alpha2 saves ~£20/year on electricity vs UPS2 in typical use. Payback ~5 years.
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