Abstract: A warm air furnace capable of reliably carrying out a fuel consumption conserving operation regardless of a heating load is equipped with an ecology operation setting unit for setting a saving operation function and a moderate operation function. The saving operation function makes a target temperature setting unit decrease a target temperature by a first predetermined temperature after a lapse of a predetermined time after a room temperature reaches the target temperature. The moderate operation function limits a target combustion amount when the room temperature is higher than the target temperature by a second predetermined temperature or more. An eco-operation switch is capable of turning the ecology operation setting unit on and off.

Abstract: A warm air furnace capable of reliably carry out the fuel consumption conserving operation notwithstanding the condition such as the heating load is provided. The warm air furnace is equipped with an ecology operation setting unit 41, 47 for setting a saving operation function which makes the target temperature setting unit 40 set the target temperature by decreasing the same by a first predetermined temperature, after a lapse of a predetermined time after the room temperature reaches the target temperature, and for setting a moderate operation function which limits the target combustion amount when the room temperature higher than the target temperature by a second predetermined temperature or more, and an eco-operation switch 30 which is capable of setting on and off of the ecology operation setting unit 41, 47.