Unit heaters are a good way to heat an unconditioned space like a garage or a basement. This type of system is usually hung from the ceiling in the corner of the space. Unit heaters can be hydronic which require a boiler for a heat source. Water is heated inside the boiler and sent through pipes by a circulator to a coil inside the heater. A fan is attached to blow air across the coil and absorb the heat which is delivered to the space. Other unit heaters can have their own heat source such as a gas burner, oil burner or electric heater cores which are built into one package. These unit heaters are usually only found in garages, warehouses or barns. They require either a gas line piped to it and a flue pipe to remove the burnt gases, or an oil line and a flue pipe. All unit heaters require an electrical line as its power source to operate the fans. The electric only unit heaters require a larger electrical line because they use a heater core and a fan.