When the time comes to replace your air conditioner, heat pump or furnace, sizing the new equipment to match your home is essential. The U.S. Department of Energy (DOE) explains the importance of accurate HVAC sizing:

  • Oversized equipment will cycle for brief periods that won’t allow it to heat, cool or dehumidify your home properly.
  • An undersized unit will cycle for long periods, and use extra energy without providing sufficient heating or cooling for comfort.

Heating and Cooling Equipment Sizing Basics

A/Cs, heat pumps and furnaces are sized according to the amount of heat they remove or supply, depending on the equipment type. Two common industry terms used for this capacity are British thermal units (BTUs) and tons:

  • Heating equipment BTU input describes the amount of fuel energy a particular unit uses in a one-hour period, but the usable heat generated depends its efficiency rating (AFUE). For example, an 80,000 BTU furnace with an AFUE of 95 can deliver 76,000 BTU of heat.
  • With smaller-capacity cooling equipment like portable, window and individual mini-split units, BTU outputs are used to describe how much energy is consumed to remove heat from a space.
  • The capacity of larger, central cooling systems is expressed in tons. One ton equates to 12,000 BTU, and system sizes increase incrementally by half tons.

How to Correctly Size HVAC Equipment

To accurately size new HVAC equipment so it comfortably heats or cools your home without wasting energy, it’s vital to have a certified HVAC professional perform detailed heating and cooling load calculations. These calculations are specific to our climate zone and based on various unique characteristics of your home such as the ceiling heights and square footage, the insulation level, the number and type of windows, the structure’s air-tightness and orientation/shading, and the number of occupants. The results are used to select the correct equipment size according to Manual S, and to ensure proper air distribution and ductwork design using Manuals T and D.

If you’re considering purchasing new HVAC equipment for your Eastern North Carolina home, contact us today at Jackson & Sons for expert HVAC sizing assistance.

Jackson & Sons, Inc.

Our goal is to help educate our customers in Eastern North Carolina (including Wayne, Johnston, Greene, Lenoir, Pitt and Duplin Counties) about energy and home comfort issues (specific to HVAC systems).