How much will I save?
Switching to a high-efficiency heating system can save you some money. You can find out just how much from the accompanying U.S. Department of Energy table.
Before buying a new furnace or boiler or modifying your existing unit, first make every effort to improve the energy efficiency of your home, then have a heating contractor size your furnace. Energy-efficiency improvements will save money on a new furnace or boiler, because you can purchase a smaller unit. A properly sized furnace or boiler will operate most efficiently.
When shopping for high-efficiency furnaces and boilers, look for the ENERGY STAR label. If you live in a cold climate, it usually makes sense to invest in the highest-efficiency system. In milder climates with lower annual heating costs, the extra investment required to go from 80 percent to 90 or 95 percent efficiency may be hard to justify.
You can estimate the annual savings from heating system replacements by using the accompanying table, which assumes that both heating systems have the same heat output. However, most older systems are oversized and will be particularly oversized if you significantly improve the energy efficiency of your home. Because of this additional benefit, your actual savings in upgrading to a new system could be much higher than indicated in the table.
AFUE in the table refers to the ratio of annual heat output from a heating system compared to the total energy consumed by the unit. For example, a furnace with an AFUE of 90 percent means that 90 percent of the fuel consumed becomes heat.
The table compares inefficient systems as low as 50 percent to highly efficient systems up to 95 percent. For example, if your existing system is only 50 percent efficient (a contractor can tell you how efficient it is), upgrading to an 80 percent efficient system will save about $37.50 annually for every $100 in fuel costs. A 90 percent efficient system will save about $44.24.
On the other hand, if your current system is already 90 percent efficient, upgrading to 95 percent will save you only $5.30 per $100 in fuel costs annually.