The Evolution of Air Furnaces

January 28, 2019


Keeping the interior of a structure warm in cold weather is as important today as it’s ever been, and in St. Louis, because of fluctuations in temperature, indoor air quality can be an issue as well. Almost all furnaces installed today are air furnaces, meaning that they take heat from one side of a heat exchanger, warm it, and then put it into the structure’s circulating air system. The air furnace of today has evolved from the simple stove of the past to the sophisticated forced-air models of today.

A Brief History

The first type of air furnace was a simple stove where the air was heated by a fire in a small compartment with coal or wood as the fuel source. While a stove was able to provide enough radiant heat to cook with and warm a room, it was an inefficient device because so much heat escaped out the exhaust flue.

The single-register or pipeless, air furnace came next, and these furnaces sent heated air up through openings in the floor. The problem with single-register furnaces is that the cool air returned through the same openings and did not circulate efficiently throughout the structure.

Finally, the forced-air furnace used mechanical methods to rapidly and efficiently send heated air throughout a structure and then draw back cool air. In recent years, advances in electronics have made very precise control of heating a home through a thermostat possible.

Is My Furnace Old or New?

If you have a gravity furnace, also known as an “octopus” furnace, then it is probably pretty old. This type of furnace has no blower motor and simply heats air in the basement of a structure then lets it rise through the ducts to the rooms above and was widely used in the 1800s and early 1900s. Originally, they ran on coal.

If you have a forced-air furnace that looks old, search for its model and serial numbers to determine age. It’s a good idea to replace any furnace over 15 years old, so call Scott-Lee Heating Company to learn more. Scott-Lee Heating Company is your experienced and knowledgeable go-to source for information regarding your air furnace needs.