As technology in all areas increases in power, there is a constant movement toward miniaturization, and this is as true in the field of heating systems as anywhere else.
Nowadays, it's possible to have a furnace of about 50% the size of one built 50 years ago, and yet get the same or greater heat output.
These come under the generic name of small gas furnaces, though the output can range from around 12,000 BTU up to about 30,000 BTU, making them an excellent choice and suitable for a wide range of applications, from the small house or apartment to non-residential locations.
These strictly non-residential locations can include a garage or workshop, where a large furnace would not be economically feasible since the furnace would be used only part of the time.
With a small furnace, the low cost means it can be worthwhile buying and installing one specially for outbuildings, since it can be cheaper in the long run than relying on portable heating such as electric fires.
For a decent small furnace, look at one that has at least 80% efficiency, since this will give enough heat output to keep a workshop warm even in cold weather, and yet will enable you to keep running costs to a minimum.
For even more cost savings, look a gas condensing furnace.
Most small furnaces can run on both natural gas and propane, and can be converted to run on one or the other.
Having a propane furnace in an outbuilding can be a good choice, since a natural gas supply may not be available away from the main residence.
It can also be a good idea to look at a furnace with a timer system which will ensure the heating is turned on a little while before the building is used, and is warm by the time you enter.
Next time you are looking for a heating system for a garage or outbuilding, take a look at what's available in small furnaces for good heating at low cost.