System prob or boiler prob?

[WaterTight]

If a boiler keeps firing up for a min and cutting out for 3 or 4 mins repeatedly, how do you rule out a system prob before you start looking at boiler?

 

[Blake]

depends if its a combi or system boiler? Could be a flow issue (pump, 2 port/3port) so overheating or a sensor issue or frozen condensate. Difficult to say without more info.

 

[dontknowitall]

Is it an oil boiler? Seems to be a few problems with these having frozen oil feeds. Enough oil will seep through to the internal pipework while the boiler's cut out. Then it will fire up again, then get starved of fuel.