Mid efficiency furnace 
A mid-efficiency, non-condensing furnace has an 80% to 90% Annual Fuel Utilization Efficiency (AFUE). This furnace type will vent exhaust gases out of the home, generally through the roof. This type of furnace is no longer available to Canadian homeowners. 

As of January 1, 2010 all new furnaces in Canada must reach an AFUE of 90% or higher. 

The AFUE, or the ratio of annual heat output of the furnace is compared to the amount the fuel it requires annually. As an example, if a furnace has an AFUE of 80%, it means 80% of the fuel energy is being converted to heat while 20% is lost. 

High efficiency furnace
A high-efficiency condensing furnace has a 90% or up to 98.5% AFUE. They contain a secondary heat exchanger to heat the air from condensed exhaust gases to reach a higher efficiency level. The process is key to minimizing wasted heat/fuel which makes the high-efficiency furnace a lucrative method to heating a home. When paired with a smart thermostat the end results are better for the environment and your bills. 

Single stage furnaces 
A single stage furnace will run at a maximum power until the thermostats heat demand is met and then shuts off.  

Two stage furnaces 
A two stage furnace has the ability to run at low or high until the thermostats heat demand is met and then shuts off. 

Modulating furnaces 
A modulating furnace can have many levels of heat output which easily maintains temperatures within the home and provides more energy and cost efficient results. These units constantly regulate output which is the biggest advantage overall. 

Variable Speed ECM  
A variable speed electrically commutated motor (ECM) has the ability to adjust speed according to the systems demands which optimizes the efficiency for specific conditions. 

Constant Torque ECM  
A constant torque ECM operates at varying speeds while maintaining steady torque and is suited for applications where the power load does not change significantly. The constant torque design uses less energy in both heating and cooling which translates to savings.