Furnace efficiency has dramatically improved in recent years. For instance, a new gas furnace today delivering 98% AFUE (annual fuel utilization efficiency) doesn’t need to be as large as an old furnace delivering 80 AFUE. To maximize your new furnace investment, it’s important to ensure that it’s sized properly for your home.

Sizing a New Gas Furnace

A new gas furnace needs to be sized properly to supply enough heat without being too large or too small for your home. An oversized furnace will cycle on and off too frequently, which compromises efficiency and comfort. In contrast, a furnace that’s too small for your home isn’t going to be able to heat your living space comfortably.

So, the formula for properly sizing a furnace involves dozens of assessments for home efficiency, climate, sun orientation, occupancy, the number of windows, as well as size and much more. This formula was developed by the Air Conditioning Contractors of America (ACCA). However, to get a working estimate of furnace size, you should use the basics of ACCA’s Manuals J, S and D (load calculation, system selection and duct design).

• To get a working estimate of the size of your furnace, you need to determine your home’s square footage, climate, furnace size and efficiency.
• Your HVAC professional will also take into account ceiling height, insulation, window treatments, your home’s sealing quality and different furnace efficiencies, when calculating lifetime costs.
• Your home’s orientation to the sun is very important. For instance, your HVAC pro will need to know which rooms are exposed to the sun and how often they’re occupied.
• An important component of furnace sizing is to consider add-on features, such as a zoning system, a whole-house humidifier, air cleaners, and other systems that can improve efficiency and  home comfort.

Fortunately, your HVAC pro is experienced and utilizes sophisticated software to ensure your new gas furnace is properly sized for your Greater Kansas City home. For more information, contact Overland Park Heating & Cooling, Inc.

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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