If you have an old inefficient ‘G rated’ boiler, then you could cut your heating bill by a quarter if you replace the boiler with a new ‘A rated’ model with modern heating controls.
Os oes gennych chi hen foeler aneffeithlon ‘gradd G’, gallech dynnu 25% oddi ar eich bil gwresogi trwy newid y boeler am fodel newydd ‘gradd A’ gyda mesurau rheoli gwres modern.