Potterton Netaheat 16/22 - Pump constantly running?

could be a motorised valve microswitch jammed! if you have a S plan system the pump and the boiler are wired into a switched live. if the micro switch is jammed then the pump AND the boiler will be constantly on, you may not realise the boiler is on cos it will only run for about 30 seconds before the boiler stat cuts out and stops the boiler from running so you may not realise it is running!

hope this helps!

KAW!
October 2007

Assuming the pump is wired to the pump supply from the boiler, it must be a faulty pump overrun thermostat.

Red Baron
September 2007