potterton puma 80 pilot light goes out after using DHW

[AlanB48]

Potterton Puma 80 combi boiler works fine for CH. When I turn the hot water tap on, the boiler fires up ok and the water gets hot (probably too hot) but when I turn the tap off the pilot goes out with the main burner.

Any suggestions?

 

[Gasguru]

Often its the DHW flow switch that sticks on after water drawoff. As a result the boiler overheats and the overheat thermostat cuts the pilot.

Pop off the front panel - on the board you should see a red LED with hot water demand. Check it goes out when the tap is turned off.

 

[AlanB48]

Thanks for the reply..
When the hot water tap is shut off the LED on the board goes out and the main burner shuts down straight away. If I only open the hot tap for a short while, then the pilot doesn`t go out.If the hot water is running for about 3 mins or more, then the pilot goes out with the main burner. During this time the water gets very hot even though the thermostat is set to minimum. Could the DHW temp. sensor be the problem?

 

[AlanB48]

Can the DHW temp. sensor be tested and if so how??

 

[geoff@cetltd]

as a rough guide, it should be around 10kohms at room temp, going down to about 3 kohms when it's up to temp