Kansas City’s cold winters mean that the size of your home furnace is critical for both comfort and manageable energy bills. It’s for this reason why furnace sizing is such a complex task, and why a “typical” furnace BTU rating can’t be given.

Common BTU ratings

Because home heating needs vary widely, furnaces are available with BTU ratings ranging from 40,000 to more than 200,000 BTU. Most furnaces fall somewhere in the 80,000 to 100,000 range.

By looking at the technical specifications, you’ll find the input BTU rating, which indicates how much energy the furnace uses to heat a home. This isn’t the same as the output BTU rating, which depends on the furnace’s efficiency. For example, a 95 AFUE (95 percent efficient) 70,000 BTU furnace will deliver about 66,500 BTUs per hour of heat energy to your home.

How much heating your home actually requires, however, depends on many factors related to the building itself, such as your insulation and windows. This means only one size of furnace will be right for your home.

Estimating Your Needs

In most areas with cold winters, a home furnace will need to generate between 40 to 45 BTUs per square foot. Using this information, you can get a rough estimate of your required furnace size based on your home’s square footage. The average Kansas City home, which is around 1,700 sq. ft., will need a furnace rated at 68,000 to 78,500 BTUs per hour.

Your heating degree day can also provide a rough estimate. Check your gas bills for July and the annual usage rates in therms. Then, multiply your July usage rate by 12. Next, subtract the resulting number from the annual usage rate. Afterwards, multiply this result by 50, and then by your furnace’s efficiency.

To obtain an accurate sizing for your home furnace, a heating and cooling professional will follow the sizing procedure outlined in the ACCA’s Manual J.

If you’re in the market for a new furnace, contact Overland Park Heating & Cooling, Inc. in the Greater Kansas City area.

Our goal is to help educate our customers in Overland Park, Kansas about energy and home comfort issues (specific to HVAC systems).

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