Your local authority must be told when you have a new or replacement boiler fitted. Your installer should do this for you, and you should receive the following certificate:
If your boiler is installed by a Gas Safe Register/, you will get a 'building regulations compliance' certificate from Gas Safe Register after the work has been completed. Gas Safe Register will also tell the local authority that you have had a new or replacement boiler fitted.
You should keep this certificate as you may need it when you sell your home.