The term “garage heater” is generally used to describe heaters that are designed to heat large, poorly insulated areas such as garages or shops. They tend to follow the basic rules that apply to space heaters or wall heaters but have specifications regarding their placement and use.
In general, garage heaters are more heavy duty than other types of heaters. There are also several types of garage heaters. For example there is the infrared heater which heats via electromagnetic radiation, transferring heat to bodies that have a lower overall temperature than the heater itself. There are heavy duty fan heaters that expel the hot air created by a fan, spreading it around the room. Infrared heaters tend to be energy efficient, and have the added benefit of being silent as opposed to noisy fan heaters, but they provide heat to certain objects only, rather than the room in general. They also tend to be harmful for one’s health, as constant subjection to the radiation can cause thermal burns and similar injuries. A further disadvantage of using infrared heaters is the high cost, as they can be up to two times as expensive as other garage heaters.
Another type of garage heater is one that expels heat created by burning kerosene or propane. These are less efficient than their natural gas burning counterparts, though all kinds of heaters that use such fuel would need to be flued, i.e. they’d need a vent or pipe to expel the waste gases and/or smoke outside. Some garage heaters use hot water, though this is not recommended due to the fact that they would expel water vapor into your garage, resulting in rust.
The best solution for garage heating is a natural gas powered heater, flued, that expels its air via fan. This heater should be placed high up in a corner, facing the opposite corner, so as to create a circulation of heat around the room.