When it comes to home heating, the more efficient your furnace is, as general rule, the lower your home heating costs will be. Fuel efficiency for oil-to-heat energy is reflected in a rating known as its Annual Fuel- Utilization-Efficiency (AFUE) rating. Presented as a percentage, the higher the number, the more heat the unit produces and the lower its environmental impact.
AFUE percentages are the common measurement of a heating units efficiency. It measures the amount of heat produced compared to the amount of fuel needed to supply the furnace. For example, a furnace with an AFUE rating of 85%, converts 85% of the fuel into heat with the remaining 15% being lost out the chimney. It’s important to understand that the AFUE only refers to the unit’s fuel efficiency (whether it’s natural gas, oil or propane) and not it’s electricity usage.
The Department of Energy defines AFUE as:
“ The measure of the seasonal or annual efficiency of a furnace or boiler. It takes into account the cyclical on/off operation and associated energy losses of the heating unit as it responds to changes in the load, which in turn is affected by changes in weather and occupant controls.”
The DoE determined in 1992 that all furnaces sold in the US must have a minimum AFUE of 78%. As of 2015, those rating have increased to:
- Oil-fired furnaces – 82% AFUE
- Gas boilers – 84% AFUE
- Oil-fired burners – 83% AFUE
In recent years, the industry has been producing more efficient units even prior to the adoption of these new rules. Typically, a furnace produced in the 70’s has an AFUE of about 65%. Today, the lowest efficiency for a new unit allowed by law is 78%, but the most efficient models can have an AFUE of up to 97%, which is close to total efficiency.
Prices for boiler of furnace units are related to their AFUE, with higher efficiency meaning a higher price point. But, the higher initial cost can often be made up through lower, more efficient energy use over the life of the unit. The electricity required to run the units can vary. This will affect the payback time along with the climate where you live, how well your home is insulated, and the rates you pay for gas and electricity.
“British Thermal Units” (BTUs) are a measure used to determine the heat efficiency of fuels. Not all fuels are created equally when it comes to heat. For example, oil heat has a BTU of 136,690 while propane comes in lower at 91,333.
The Cost of Oil VS Propane
When you compare oil burners with a 90% AFUE against propane systems with an AFUE of 94% using the NH DoE costs of $2.18 per gallon for oil vs. $2.57 for propane, oil heat provides 57,257 BTUs per gallon versus propane’s 33,761. While the AFUE of the propane unit is higher, the fact that oil produces a higher BTU rate makes the overall operating cost of a less efficient oil-fueled unit less expensive to run, plus the upfront cost of the unit may be lower due to its slightly lower AFUE percentage rating.
If you live in New Hampshire, consider installing an oil furnace or boiler with an AFUE of over 90%. Oil has a higher BTU output per gallon of fuel. Though highly efficient oil heating systems are more expensive initially, it will provide a better ROI over the life of the unit. Properly maintained, an oil burning unit will last 15 – 20 years, providing you with a significant savings throughout its lifetime!
We sell the highly efficient Energy Kinetics System 2000 multi-fuel heating system. To learn more, click here to download the brochure or call us to speak to a home heating expert.