@bazbt3

It snowed again, the gritter failed to make an impact (but I'm not sure one came this way.) The school was shut so World Book Day didn't happen here, my wife was late from her night shift (waiting for staff to arrive), and the boiler stopped working.

What to do when the condensing boiler repeatedly stops working in the winter, it gurgles like a boiling kettle before the error indication appears, and resetting the thing fails:

It's likely that the condensate drain pipe is frozen outside the home.

1. Find the condensate drain pipe; it'll project out of the bottom of the boiler case,
2. Locate it outside,
3. Pour hot water over the pipe outside,

If that doesn't clear the ice:

1. Turn off the boiler at the mains switch,
2. Find a bucket or a washing up bowl,

At this point I must stress that you need to be aware if you mess this bit up the very least of your worries will be the size of the repair bill:

1. Disconnect the pipe from the bottom of the boiler and collect the spurty water on the wall behind and the floor beneath the boiler, anywhere but the bowl or bucket,
2. Leave the vessel there to collect water,
3. If you have a hose that you can connect to the drain fitting, fit it and drop the end into the vessel until the outside temperature rises,
4. Turn the boiler on again; no gurgling!