Cooking oil contained in a fuel-fired deep fat frypot is heated utilizing a recirculating flow of combustion gas produced by an induced flow fuel-air burner. A squirrel cage type centrifugal fan draws a fuel-air mixture inwardly through the burner into an inlet chamber in which the combustion gas is formed. The hot combustion gas is discharged from the fan into a supply chamber, flowed from the supply chamber into and through external heating passages extending rearwardly along the opposite exterior side surfaces of the frypot, and then enters an external heating passage extending along the rear frypot wall. From this rear passage the combustion gas is drawn forwardly through generally triangularly shaped heating tubes extending horizontally through the frypot cooking zone, into and through a return plenum, into the fan where it is mixed with a fresh supply of combustion gas from the inlet chamber, and is then discharged into the supply chamber. During burner operation excess combustion gas is discharged to atmosphere through an appropriate vent stack. A motorized inlet damper is mounted on the inlet plenum and is operable to admit ambient air thereinto to rapidly lower the recirculating gas temperature to prevent oil temperature overshoot. Rigid insulation material is positioned in lower interior portions of the heating tubes to increase the gas flow velocity therethrough and to shield the lower "cold zone" of the frypot from tube heat. In an alternate embodiment of the frypot the fuel-air burner is replaced with electric heating elements operatively disposed within the supply chamber.