Overhead and shop heat. Episode twenty-five of Gas Service Animated: heating garages, warehouses, and shops from the ceiling.

Shops and warehouses heat from above. The unit heater is a self-contained box — fan, burner, and heat exchanger — hung from the structure and aimed where you need warmth. The duct furnace is similar but lives inside ductwork, borrowing a separate blower. And infrared heaters — glowing high-intensity emitters or long radiant tubes — hang overhead and shine heat downward. Three different tools, one shared job: warm a big open space.

Infrared heaters cheat the physics of big buildings. Instead of heating air first, they send radiant energy downward — it passes through the air and warms floors, machines, and people directly. The warm slab then re-radiates gently into the space. In a tall, drafty building, heated air just stratifies at the ceiling; radiant heat lands where the workers are.

Radiant heaters need clearance in every direction — above and beside, but especially below, where the beam is aimed. Listed heaters follow the manufacturer's clearance sheet exactly. And the code adds something clever: where combustibles are stored, signs must be posted stating the maximum stacking height that keeps stock out of the clearance zone. Because storage creeps — pallets stack a little higher every month, until the top row is baking in the radiant path.

Venting overhead follows familiar rules. A draft-hood unit heater vents like any Category One appliance — proper connector rise, secure joints, clearances. Unvented infrared heaters instead rely on the building: the code calls for supply and exhaust of at least four c-f-m per thousand B-T-U per hour of input, with exhaust openings above heater level. And direct gas-fired makeup-air units fire straight into the airstream by design — all their air ducted from outdoors.

Everything overhead hangs on its hardware. Suspended heaters need hangers and brackets of noncombustible material, sized for the weight, and vibration-isolating hangers where the unit shakes. Infrared heaters must be fixed in position independent of the gas and electric lines — piping is never the support. The gas connection itself follows the connector's listing, with no strain on the piping.

Air and fire stay interlocked. A duct furnace lives inside the duct, so it sits on the pressure side of the blower with its controls outside the airstream. Makeup-air units must prove their outdoor dampers open before the main burner lights, and relief openings keep the space from over-pressurizing. The principle is simple: no airflow, no fire.

On a service call, walk the whole space. Measure clearances with the building loaded the way it actually runs — stock stacked, racks full. Check every hanger and bracket. Confirm the connector is listed and unstrained. Prove venting or ventilation: draft on vented units, open air paths and working dampers on the rest. Then verify against the manufacturer and your company's procedures.

Overhead heat: pick the right tool, keep the clearance zone empty, hang it right, and interlock air with fire. Next episode: food service appliances and pool heaters.