Gas Furnace vs. Square Footage

Furnace

• A furnace works with your air conditioning system if you have a central heating and cooling system as part of your overall heating ventilation and air conditioning system (HVAC). Furnaces are fueled by either natural gas, propane, electricity or coal. Most homeowners in the United States fuel their furnaces with natural gas. A furnace heats air, and blowers distribute and force the warmed air through your home’s ductwork and vents.

Square Footage

• Square footage is a measurement calculation based on the length and width of a physical space. It is calculated by multiplying the length of the space by the width of the space. For example, a room that is 10 feet long and 12 feet wide would measure 120 square feet (length times width). The entire useable space of a home commonly is referred to in terms of the home’s square footage. In this case, the individual “livable” areas, such as the bedrooms, kitchen, living room, hallways etc. are measured and the total for each room is added together to get the grand total square footage of the home; this might be referred to as a 1,500- or 2,000-square-foot home.

Similarities

• Square footage is one of the main measurements used to determine the correct size furnace needed to heat a home properly. For example, a 2,000-square-foot-home might require a furnace that has a 100,000 British Thermal Unit (BTU) capacity. However, in addition to square footage, the estimator also factors in the ceiling height to calculate the cubic foot measurement of the rooms in the home, and factors in windows, sunlight exposure, the number of stories of the home and the climate where you live. The additional measurements are used to calculate what is called the “heat load,” which is what professionals use to make a final furnace size recommendation.

Differences

• Furnaces have different BTU heating capacities, and range from 20,000 to 200,000 BTUs for residential heating. Select the furnace based on the heat load calculation and the corresponding BTU capacity that the furnace should have. In essence, the measurements for a furnace are somewhat fixed, but the measurements for a home can be variable. Homes have different square footage. After factoring all the variances, an estimator might recommend a 90,000 BTU capacity furnace for a 2,000-square-foot ranch-style home, and recommend a 160,000 BTU capacity furnace for a 2,000-square-foot home with two stories and a basement.