There are two main efficiency options when it comes to Furnace selection for your home. The standard efficiency 80% Furnace and the 96% High Efficiency Furnace. We are here to help clarify some of the differances between the two options.

AFUE

AFUE stands for Annual Fuel Utilization Efficiency and is a measurement of how efficiently your furnace is converting the fuel into heat. An 80% Furnace will us about 80% of its total BTU input for heat and a 96% furnace will use about 96% of its total BTU input for heat.

80% Standard Efficiency Furnace

An 80% AFUE Furnace is designed to use 80% of the total heat produced from the gas burners to heat your home. The other 20% of the heat is exhausted out through the exhaust vent. This type of furnace is called a none condensing furnace because the exhaust gases exiting the furnace are at a much higher tempurature. This prevents condensation from forming inside of the exhaust vent and allows the furnace to us a metal B vent for venting.

96% High Efficiency Furnace

A 96% AFUE High Efficiency furnace is designed to use 96% of the total heat produces by the burners to heat your home. The other 4% of heat is exhausted through the exhaust vent. They accomplish this by utilizing a 2 stage heat exchanger where the first stage is designed similar to an 80% furnace and the second

stage looks more lika a radiator with fins. This 2 stage heat exhanger design allows the air going through your air ducts to absorb more heat as it makes its way through the heat exchanger and then to your supply registers.

This Furnace is called a condensing furnace, since more heat is absorbed into the air moving through the air ducts the exhaust gases are much cooler than an 80% furnace. Since the exhaust gases are cooler, they will condens inside of the secondary heat exchanger and the exhaust vent itself. This is the reason why 96% furnaces use a PVC exhaust vent instaed of a metal vent. A PVC vent will not rust from condensation and is much better at allowing the condensation to flow back into the furnace. The furnace then drains this condensation through a factory P trap and down a designated drain.

Which Type of Furnace should I choose?

In the Gresham area there is a good mix of both types of furnaces.

The type of furnace best suited for your home will depend on Furnace location and existing conditions. An 80% furnace is a non condensing furnace and utilizes a metal B vent for exhaust. A 96% furnace is condensing and will utilize a PVC vent with a drain.

This blog is written by Anton Bocharov (Owner) of A&B Air Solutions LLC.