While you wait for answers, we may have found some information which could help you.
Click here for Coming System RadiatorsUnexplained noises?
how can I fix my old glow worm central heating boiler model 65-80?
Grundfos UPS 15 45 x18 central heating pump?
Heating?
Grundfos Pump Plan wiring Centre part 96437234?
Problem after changing ch pump on a grundfos pump plan?