Abstract: A heater for a grain bin is attached to the inlet flange of a centrifugal inline blower and comprises a housing having a vertical front wall attached to the inlet flange of the blower and a parallel vertical rear wall. The front wall has an opening aligned with the opening into the blower. The rear wall has an opening aligned with the opening in the front wall so that the majority of the air entering the blower passes straight through the housing from the rear wall to the front wall. A sleeve surrounds the opening in the rear wall and induces some flow from the housing to mix with the flow into the blower. The combustion chamber is attached to the rear wall through an opening in the rear wall above the sleeve. The housing has two side walls converging to an open top through which air can escape. When heated air is required an air flow is induced from the combustion chamber to mix with the air flow through the housing to heat the total air flow.