I have replaced the pump overrun switch on my boiler when the pump stopped working. It has worked for 4 days and has gone off again, no power to pump. What can I do next?

Dave Thomson, March 2007

from ex thorn engineer

the supply to the pump live is via the (PORS) pump over run thermostat at all times-- when cold the pump picks its live supply from the "switched live" via the PORS when the stat gets hot the supply comes from the permanent live via the PORS. If you are sure the pump is not live then I'm afraid the PORS is faulty -as a temp measure change the wire to the pump at the boiler control panel onto the switched live. This will feed the pump anytime the boiler is switched on but you will have no overrun. May result in over heat thermostat operating and shutting pilot off due to residual over heating

this is a very old boiler -- seen hundreds of them

make sure all three cables are sound and are in continuity from PORS to the control board - no loose or damaged wires.???

dave b

dave broadbent, June 2007