BTU stands for British thermal unit, the standard metric for measuring the heat input of furnaces. One BTU is the amount of heat needed to raise the temperature of one pound of water by 1 degree Fahrenheit, or about the amount of energy given off by a birthday candle.
If you’re shopping for a furnace, you need to know your home’s heating requirements and the corresponding BTU rating of the new furnace. If you choose equipment with too low of a rating, it won’t produce enough heat on bitter winter nights. If the BTU rating is too high, the furnace will cycle on and off frequently, resulting in uncomfortable temperature swings and greater wear and tear on your system.
HVAC contractors can calculate the size of furnace you need by performing various load calculations found in Manual J. Accurate calculations are quite complex and include factors, such as ceiling height, window layout, home orientation, insulation levels, room sizes, average occupancy rates and more.
Rule-of-thumb sizing techniques also exist based on climate and square footage. In Dayton’s cooler climate, a ballpark guess is that your home might require 40 to 45 BTUs per square foot. If you have a 2,000-square-foot home, you’ll be looking for a furnace with somewhere around 80,000 to 90,000 BTU output. However, this is just an estimate. To enjoy the best comfort and energy efficiency, have an HVAC contractor perform the formal load calculations.
Be sure to consider the BTU input as well to determine a furnace’s efficiency. The output may be 80,000 BTUs, but if the furnace requires an input of 100,000 BTUs to continue running, it’s only 80 percent efficient. This percentage, called the Annual Fuel Utilization Efficiency (AFUE), determines how much you’ll pay each month to operate your furnace. It pays to invest in a furnace with an AFUE rating closer to 100 percent. The upfront investment in higher-efficiency equipment is greater, but monthly energy savings will help your furnace pay for itself over time.
To learn more about choosing the right furnace for your Dayton home, please contact Ace Hardware Home Services, Inc.
Our goal is to help educate our customers in Dayton, Ohio about energy and home comfort issues (specific to HVAC systems).
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