Electrical ignition
In high efficiency furnace electronic ignition is used instead of gas pilot light. It ignites only when furnace needs to be turned on and then goes off again. Instead constantly lighting the pilot light ignition saves energy by turning on only when light is required.
Multi stage heating
Low stage heating is used when normal heating is required in the home while the high stage is turned on at the time of extreme cold winter months.
Secondary heat exchanger
Second combustion chamber captures the exhaust gas which usually escapes the unit. This exhaust gas is condensed and converted into liquid again to repeat the process of heating. This process helps to save the fuel.
Sealed condensing unit
Sealed combustion unit uses outside air for its process instead of using the air from indoors. This process saves energy as they do not provide the air on which it already worked hard to make warm.
Motor with variable speed
Most of the furnace with high energy efficiency use blower motor with variable speed. Instead of turning the motor on/off at regular intervals they adjust the speed of the motor as turning on the motor requires 6 times more energy.