Our Boiler only runs a few seconds of hot before going cold. if you switch it off 30 seconds or so, you can get the same thing again.
The Boiler is a Glowworm Swift Flow 75/80 (It says inside)
Yes, just the hot water. The heating is all fine and works well. There's no pattern either, sometimes it can be fine, others it's impossible to get more than a few seconds. Both with the heating on and without.
It seems to fire, but but that could be the heating part working?