During the cooling mode variable speed systems typically result in an efficiency gain of about 1 seer seasonal energy efficiency ratio.
Retrofit variable speed furnace motor.
In recent years new furnaces with bpm motors have gained market share.
The differing speeds control heating and cooling airflow through the home.
According to the manufacturer s documentation your furnace should have a 3 or 4 speed blower motor.
Should be if circ is on lowest speed there is no way to retrofit an existing furnace with an variable speed ecm.
More efficient motors are available evergreen for retrofits but they pretty much function like standard multi speed psc motors.
When the r g circuit is made the blower motor operates on heating speed.
Is it louder when heating cooling.
But over the years several manufacturers have developed variable speed electronically commutated motors ecms specifically designed as retrofit replacements for faulty psc motors.
Since 1985 furnace manufacturers have used higher efficiency variable speed bpm fan motors also known as electronically commutated motors or ecms in some high end residential furnaces.
And while not all contractors consistently offer ecms those who do often report increased profits as well as improved customer comfort and satisfaction.
Compared to a conventional single speed furnace a variable speed furnace performs better and uses about two thirds less electricity.
The problem is the furnace control module doesn t use a separate speed when the unit is running in continuous fan mode.