and below and spaced from the oven bottom 11 forming a heat space 25 in use the heated air in space 25 heats oven bottom 11 to supply radiant heat to the cooking chamber shield 21 has openings 22 and 23 in which flame spreaders 18 and 19 are respectively located and acts in conjunction with flame spreaders 18 and 19 to protect oven bottom 11 from direct contact with the flames from burners 16 and 17 located in the space 25 between the oven bottom 11 and oven bottom shield 21 is a bottom shield duct 24 preferably of a hollow rectangular configuration which extends from the front area of the oven toward the rear duct 24 has a plurality of inlet vent holes 26 26 on either side thereof as can be seen in fig1 the width of flame spreaders 18 and 19 is slightly less than their respective openings 22 and 23 leaving four gaps only two of which 27 and 28 are shown between the flame spreaders 18 and 19 and the oven bottom shield 21 the gaps serve to permit heated air to pass from below the oven bottom shield 21 into the space between it and oven bottom 11 the heated air thus passing through gap 28 for example enters duct 24 through the vent holes 26 26 and as will be apparent hereinafter passes through duct 24 toward the.