I'll try to give you some more detail -
The heating cycle obviously changes with the heating demand but typically when up to temperature the cycle is approx 20 secs on 90 secs off.
With the heating off the gas operates correctly with the taps.
With the heating on and running taps together I...
Boiler make / model
Gas Glow Worm Swiftflow 75
Heating OK.
Hot Water OK.
Noise problem.
Problem for approx 8 weeks.
No recent changes to system.
On central heating start up everything OK.
When central heating at working temperature noise from boiler starts.
Noise is a high pitch...
