Oil boiler on constantly

[Woosh]

Hi There

Hope someone can help. We have a HRM Wallstar oil boiler controlled with a Danfoss FP715 programmer. Last night, when we turned the heating off as normal, the boiler decided to stay on all night. The wall thermostat was set at zero, the danfoss controller swithed to off but the boiler carried on running.

The only way to stop it running is to turn the temperature on the bolier down to stop.

Anyone know what the problem could be?

Thanks

Ian

 

[wilhelm]

has it been serviced recently?
sounds like someones left the overide switch to "test" in the boiler casing.
it should be set to "prog"

 

[Woosh]

Not been serviced recently. Have done nothing that we don't usually do

 

[cjb1971]

Do you have a frost stat at all?If you do this may be set too high.

 

[simond]

Failing the above, it could be a stuck motorised valve.