While you wait for answers, we may have found some information which could help you.
Click here for Baxi 105e PumpGrundfos 1550 ch pump installation?
Unexplained noises?
grundfos MK 2 15/50 x 18 playing me for a fool?
Grundfos UPS 15 45 x18 central heating pump?
Problem after changing ch pump on a grundfos pump plan?
Turn dial which way to increase speed?