The BTU (British thermal unit) provides the key to understanding heating your home with a combustion furnace. The size of heating systems is given in BTUs, although their rating doesn’t translate directly to the amount of total heat they produce. Instead, it’s the relationship between BTUs and how well that the system uses the energy that the fuel creates.
All combustion furnaces and boilers carry AFUE (annual fuel utilization efficiency) ratings that tell you how much of the fuel it uses goes toward actual heating and how much it creates as waste gases. The HVAC industry expresses the AFUE as a whole number, but it’s actually the percentage of heat that’s usable verses the amount that’s wasted. The minimum AFUE rating currently stands at 80 for gas furnaces, which means that 20 percent of the gas it uses is lost.
When HVAC professionals size heating systems for homes, they assess how energy efficient the home is to discover its heating load. A well insulated home and one with few air leaks will have a lower heating load than one with inadequate insulation or leaking doors, windows and walls. Contractors use software called Manual J to complete this detailed analysis that includes many characteristics of your home that drive its energy efficiency. The second part of the analysis involves the system selection process, total BTUs and efficiency ratings. The AFUE ratings range from 80 to 99. More efficient systems cost more initially, but you make the investment back in lower long term energy bills. Once you’ve decided on the best system for you, the contractor will apply the AFUE rating to the BTU capacity to find the best size for your home. The right BTU capacity ensures lower energy bills, a more comfortable home and a longer lifespan for your system. If you’d like to learn more, contact Russell’s Heating & Cooling, providing top-notch services for Hampton Roads homeowners. Our goal is to help educate our customers in Chesapeake, Virginia and surrounding areas about energy and home comfort issues (specific to HVAC systems). For more information about BTUs and other HVAC topics, download our free Home Comfort Guide or call us at 757-750-1831. Credit/Copyright Attribution: “geralt/Pixabay”