I Need to Buy a New Furnace. What Do I Need to Know?

Step 1: Decide Between Gas and Electric

Your first decision is fuel type. If you are in a northern climate and natural gas is available at your home, a gas furnace is usually the best choice because gas heat is efficient and well suited to cold winters. In milder climates, or where gas service is not available, an electric furnace or a heat pump may make more sense. Your existing heating equipment is a good starting clue, since most homes are set up for one fuel type already.

Step 2: Find Your Furnace Capacity

Furnace heating capacity is measured in BTU. To determine the capacity you need, remove the service panel from your existing furnace and look for the BTU rating on the nomenclature plate. You will usually see two numbers, an input rating and an output rating. The input is the amount of fuel energy the furnace consumes, and the output is the actual heat delivered to your home. Older gas furnaces are often around 80 percent efficient, so a furnace with a 100,000 BTU input produces roughly 80,000 BTU of output.

Step 3: Choose the Nearest Size and Round Up

Gas furnaces are sold in 20,000 to 25,000 BTU increments. You do not have to pin your heating requirement down to the last BTU. Get as close as you can to the capacity you need, then select the furnace with the nearest available capacity, rounding up when you are between two sizes. Replacing a furnace that has kept your home comfortable for a season or two with one of the same capacity is generally a safe, reliable approach.

Get Sizing Help Before You Order

If you are unsure about fuel type or capacity, AC Direct support can help you confirm your selection before you buy. AC Direct sells heating and cooling equipment online and ships it to you, so you can order the right furnace with confidence and have a local licensed contractor complete the installation. Every order is backed by the AC Direct Price Promise.