Potterton Suprima 80L Boiler fires with no call for heat

[K2harry]

Disconnected thermostat and frost stat but boiler still keeps firing up as if there is a demand for heat. Programmer is switched to off.

Cylinder 2 port is closed, central heating open

Anybody any ideas please. Boiler fires up and then down as if satisfied then fires up pretty much straight away again

 

[seco services]

have you got two of these ?

you say heating one is open ?
is it jammed open ? then it will call the boiler to keep firing up.

 

[combispecialist]

faulty ch 2 port then,shouldnt be open if theres no call for heat,microswitch sticking sending permanent live to boiler

 

[K2harry]

brilliant

Many thanks