Drayton LP522 is a central heating timer/programmer, not a boiler.
You don't say the make/model of your boiler. Som eboilers do come on for a few 10s of seconds ehilst "off", in order to exercise the pump and to clear fumes form the burner chamber.
For how long does your boiler come on?
If it is coming on and staying on, Is the programmer actually telling the boiler to turn on?
Is the programmer actually supposed to control the heating? Has the boiler just been mis-wired to run all the time off the room thermostat?
If you can advise the model of your boiler and give a proper description of what happens, we can maybe do some diagnostics
acp, March 2017
