Glowworm Swiftflow 100

Check the wiring first. You find a one has detached itself or broken. You say the pilot flame is still lit, so this would indicate that the thermocouple is still OK. So check the motorised valves, especially the micro-switches, are making and breaking their circuits correctly, and that all the thermostats are working properly.

If a valve or thermostat isn't calling for heat correctly, then the boiler will not fire up when it should.

In message , Neil writes

Is there 24V at the gas valve?

I.e. the question is whether the pcb is delivering the volts to the gas valve or not. It is a common pcb fault, although it could be caused by a sensor failure. You'll find an indication on the pcb as to which connectors they are on.

If it's the pcb, phone me on 01923 229224, you can't look at my website atm as the server is down

Other have mentioned the idea of giving it a good visual once over. Much more likely to fail than the gas valve (IMHO) is the air flow proving switch. I don't know what sort of technology is used on the Swiftflow. Many use a a pair of tubes in the air flow connected to a diaphagm switch.

If the pilot's OK, then it can't be the APS

Sorry I assumed a permanent pilot type.