I wasn’t going to test the boiler until I could get the gas cabinet vent in and test the connections properly but I got impatient.  I opened the doors and switched the boiler on.  I now have a tank of hot water and a fault to find.

It works fine on water only but when I try to get hot air out it times out after 20 or so seconds and the red fault light comes on.  Another job for tomorrow I think.