While complete boiler failure can appear serious, there are many possible causes, ranging from a crack in one of the boiler's cast iron (or aluminium) sections, to a broken seal on the boiler pump.
To determine what’s causing your boiler to shutdown ask yourself the following questions:
Is the power supply on?
If there’s no power running to your boiler, contact your electricity supplier who’ll be able to help rectify the problem.
Is the gas or oil supply switched on?
If the gas stopcock is on but no gas is present you’ll need to contact your local gas supplier.
If you have an oil boiler, read the gauge and check that there’s enough oil in the tank.
Is the pilot light on?
If the pilot light has gone out, follow the relighting instructions in your manufacturer's manual.
If your boiler model doesn't have a pilot light, press the de-blocking button. If that doesn't work, check the central heating pressure is set to the manufacturer's instructions (this should be approximately one bar).
Is the central heating programmer in the 'on' position?
Try firing up your boiler by setting the thermostat higher than the current room temperature.
Does the central heating timer work?
Check that the timer on your central heating controls works and is set to the appropriate times. If you find that you cannot change the settings it’s possible that the batteries are flat or there’s a problem with the power source.
Is the central heating pressure correct?
Check that the pressure is set to the manufacturer's instructions (this should be approximately one bar).
Has the condensate pipe frozen?
As the condensate pipe transfers condensation from your boiler to the outside drain, during cold weather it’s possible for it to freeze.