Potterton Puma 100 DHW flow switch?

[mattyf]

Hi

Have a potterton puma 100, the ch is fine and Hot water ok but the boiler occasionally makes grumbling noises when on HW only and the pilot goes out (intermittent). Is this likely to be the DHW diaphragm flow switch sticking causing over heat and lock out or a problem with the diverter valve?

Cheers

 

[Agile]

If the problem occurs immediately AFTER using DHW then its likely to be the DHW flow switch sticking.

If it only occurs when CH is selected then its more likely to be a temperature control problem associated with the heating mode.

Tony

 

[ChrisR]

See if the red DHW light, on the pcb, goes on and OFF smartly when tap is turned on and off.