Apparatus to deliver gas to feed at least a burner in an apparatus fed by gas, or by a mixture of air/gas, wherein said gas delivery apparatus has a delivery pipe that extends from an entrance end to a gas delivery end, the following being present one after the other along said delivery pipe: - an entrance component with two electro-valves (18a, 18b) coaxial with or separate from each other, and cooperating with at least a first aperture present in said delivery pipe and held in a normally closed position by two respective holding springs (20a, 20b), said electro-valves (18a, 18b) being able to be positioned on each occasion in an open position in relation to the action of at least an electrically powered coil associated with one or both of said electro-valves (18a, 18b); - a pressure regulator provided with a shutter cooperating with a second aperture present in said delivery pipe and connected to a first regulation membrane defining a regulation chamber in which the internal pressure is equal to atmospheric pressure, said first regulation membrane also being connected to a regulation spring configured to define the pressure of the gas downstream of said second aperture in relation to the compression force applied to said regulation spring by means of a mechanical calibration device; - a flow rate regulator comprising a fixed body fixed in said delivery pipe and with a through aperture, a mobile body provided with a shutter portion mating with said through aperture to define on each occasion the section of passage of the gas in relation to their reciprocal position and a second movement member configured to position said shutter portion at least between an open position and a partly closed position, in which respectively said through aperture is open and said through aperture is partly closed by said shutter portion. - an entrance component with two electro-valves (18a, 18b) coaxial with or separate from each other, and cooperating with at least a first aperture present in said delivery pipe and held in a normally closed position by two respective holding springs (20a, 20b), said electro-valves (18a, 18b) being able to be positioned on each occasion in an open position in relation to the action of at least an electrically powered coil associated with one or both of said electro-valves (18a, 18b); - a pressure regulator provided with a shutter cooperating with a second aperture present in said delivery pipe and connected to a first regulation membrane defining a regulation chamber in which the internal pressure is equal to atmospheric pressure, said first regulation membrane also being connected to a regulation spring configured to define the pressure of the gas downstream of said second aperture in relation to the compression force applied to said regulation spring by means of a mechanical calibration device; - a flow rate regulator comprising a fixed body fixed in said delivery pipe and with a through aperture, a mobile body provided with a shutter portion mating with said through aperture to define on each occasion the section of passage of the gas in relation to their reciprocal position and a second movement member configured to position said shutter portion at least between an open position and a partly closed position, in which respectively said through aperture is open and said through aperture is partly closed by said shutter portion.