Furnace Replacement in Indianapolis (Part III): Efficiency Options

By: Brian Schutt  |  December 3, 2010

(Chart from American Council for an Energy-Efficient Economy) Calculate Dollar Savings per $100 of Annual Fuel Cost To determine savings from the table to the right, find the horizontal row corresponding to the old system’s AFUE, then choose the number from that row that is in the vertical column corresponding to the new system’s AFUE. That number is the projected dollar savings per hundred dollars of existing fuel bills. For example, if your present AFUE is 65% and you plan to install a high-efficiency natural gas system with an AFUE of 90%, then the projected saving is $27 per $100. If, say, your annual fuel bill is $1,300, then the total yearly savings should be about $27 x 13 = $351. 2. Calculate Return on Investment ROI = first year savings ÷ installed cost example: ROI = $351 ÷ $2,500 = 0.14 = 14%

To continue our trip into the glorious world of furnaces, and what all you Indy area readers should do should the worst case scenario become a reality, we are looking at the efficiency options available for furnaces and how they can save you money.  If you missed parts 1 and 2, we talked about the heating going out in part 1, and furnace brands in part 2.  Efficiency in furnaces is shown in Annual Fuel Utilization Efficiency (AFUE) which measures the amount of heat actually delivered to your house compared to the amount of fuel that you must supply to the furnace.  As of January 1, 1992 the required minimum efficiency in the United States is 78%.

Standard Efficiency

The range of options in efficiency ranges from brand to brand.  The minimum or standard efficiency system available in an 80% efficient system.  The good thing is that many systems in need of replacement right now are well below this efficiency, and you’ll therefore receive a nice bump even if you only go the standard route.  Some of the features you’ll get with an 80% system are:

  • Exhaust fan controls the flow of combustion air and combustion gases more precisely
  • Electronic ignition (no pilot light)
  • Compact size and lighter weight to reduce cycling losses
  • Small-diameter flue pipe

High Efficiency

Most brands move from the 80% efficiency system to a 90% efficiency system.  This is considered “high efficiency”, but does not quality for the Federal Energy Star tax credits that expire at the end of this year.  However, once that incentive goes away, the 90% option is a great option for someone hoping to reduce emissions and bills, but without paying for the “Cadillac” systems.  90% efficient systems and above have a variety of internal improvements over standard efficiency systems, chief among them is a sealed combustion chamber, which allows less heat to escape during the heating process reducing energy usage.

Moving up the ratings, I’ll jump to 95% efficiency furnaces.  It should be noted that some brands have options all the way to 98.2% efficient.  The infrastructure of these are much the same as the 90% option described above, with some of the improvement coming from smarter systems that reduce the energy during the heating cycles.  You’ve no doubt heard about the $1500 Federal tax credit for Energy Star systems, well that expires at the end of the month.  So, Indianapolis home owners, if your furnace is on it’s last legs now is a great time to get a bump in efficiency, reduce your monthly expense and emissions, and get a tax credit that will save you up to $1500.  Not to mention, the many incentives offered by local providers like Citizens Gas, and Duke Energy.

So if you know the brand you want, you should now have some idea what efficiency system is best.  So much of the decision will be finding the right HVAC contractor, who can give you the pricing you need.  If you’re in Indianapolis, Zionsville, Westfield, Carmel or Fishers we would love to be one of the firms you consider!

Brian Schutt


is the co-owner of Homesense Heating | Cooling. Born and raised in Indianapolis, he loves the city and its people, and is committed to bringing a servants mindset into the heating and cooling industry. One of the ways he does that is to translate the technical language of HVAC into the manageable and understandable for homeowners.

Have a question? Tweet him and you'll get an answer promptly.

Posted in: Heating

HVAC Service Areas: