AFUE & Efficiency

What 80% and 96% mean on a bill, and when the upgrade pays back.

5 articles

• AFUE — What 80% and 96% Actually Cost to Run

  The percentage is easy. The payback calculation is the part that decides, and it is local.

• Temperature Rise — The Nameplate Number That Says Whether It Was Set Up Right

  There is a range printed on the furnace, and a thermometer will tell you whether the installation is inside it.

• The Blower Motor Is a Bigger Electricity Bill Than People Expect

  The furnace's efficiency rating says nothing about the largest electrical load in the house's HVAC system.

• What an Annual Service Should Actually Include

  Two companies both call it a tune-up. One of them takes readings.

• New High-Efficiency Furnace Short Cycles — Usually the Sizing

  The upgrade from 80% to 96% adds a fifth more heat from the same size box. Keep the input the same and you have just oversized the house by 20%.