What Size Furnace Do I Need & How is it Determined?

Installing the correct size furnace in your home will have an impact on your home’s comfort level and your utility bills. Any time you replace an existing home furnace, it’s important to take steps to replace it with a unit that’s properly sized for your home. Here are some consequences of having the wrong size of furnace and tips for how to select the right-sized unit.

Why Furnace Size is Important

With the wrong size furnace in your home, you will experience issues. If the furnace is too small to properly heat your home, the unit will wear out faster than in optimal conditions and it may not properly heat your home during low temperatures. As a result, you may notice pockets of warm air and cold air in the house, leaving some rooms uncomfortable. A furnace that is too small may also require more maintenance because it has to work harder to heat your home.

Conversely, if the furnace is too large for your home, it will cost more upfront and it will also require significant maintenance throughout its lifespan. The furnace will run through the stop and start cycle frequently, which is very hard on a furnace, leading to a shorter life and significant wear and tear on the unit. You’ll also see higher utility bills, since the unit consumes a large amount of power each time it starts up.

When the furnace is sized properly for your home, it will keep you comfortable no matter the weather and without incurring significant wear and tear.

How to Determine Furnace Size

Homeowners are required by many building departments to have a load calculation performed within the home before selecting a new home furnace. This helps to ensure a proper fit.

Our HVAC service professionals can perform a load calculation and ensure that you select the right size furnace for your home.

Variables taken into consideration when determining furnace size include:

• Size or square footage of your home
• Layout and floorplan
• Your home’s direction
• Your home construction and level of insulation, and
• The type of windows in your home.

Furnace Efficiency and Furnace Size

A furnace’s efficiency plays a big part when choosing a furnace. As a rule of thumb, try to choose the most efficient furnace you can afford, keeping energy savings (operating costs) as well as purchase price in mind. A high-efficiency furnace generating 100,000 British thermal units (BTU) with a 93 percent rating produces significantly more heat than the same-sized, less-expensive furnace with an 80 percent efficiency rating. By buying a furnace with greater efficiency, it may be possible to use a smaller unit and receive the same amount of heat.