Burner with grille and heating installation fitted with such a burner

A gas burner comprising:

• means forming a first chamber into which a first supply of air and combustible gas is introduced for mixing;
• means forming a second chamber located adjacent to the first chamber and sealed off therefrom for receiving a second supply of air and combustible gas that becomes mixed therein;
• means for supplying separate mixtures of air and combustible gas to the first and second chambers;
• means forming a third chamber located opposite the first and second chambers for combusting mixed air and combustible gas passed from either the first or second chambers;
• a first flame stabilizing porous plate, separating the first and third chambers;
• a second flame stabilizing porous plate separating the second and third chambers, the first and second plates located in near coplanar adjacent relation;
• electrical ignition means located in the second chamber and extending through the second plate into the third chamber, the ignition means having a spark gap disposed in the third chamber for igniting the air and combustible gas mixture passed from the second chamber, through the second plate, to the third chamber, and subsequently igniting the air and combustible gas mixture passed from the first chamber, through the first plate, to the third chamber.