What is a furnace?
Central heating as we know it today got its start in the Roman Empire. Modern central heating systems are efficient enough that they typically won’t require additional energy-wasting localized or space heaters. A central heating system uses some form of energy combustion or release, be it from a furnace or furnace and boiler combination.
A gas furnace is a home heating appliance that runs off of natural gas. The natural gas is ignited in the furnace, warming up the air, which is then delivered throughout the home. Electric furnaces, gas furnaces and convection heaters all have their strengths and weaknesses.