Variable Speed Furnace Fan Retrofit

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.

Variable speed furnace fan retrofit.

Compared to a conventional single speed furnace a variable speed furnace performs better and uses about two thirds less electricity. The evergreen im is a variable speed permanent magnet brushless dc motor the same type of motor used in furnaces equipped with an ecm. Either replace the furnace with one equipped with a variable speed blower or stick with single stage equipment. The control module only uses two speeds one for cool and one for heat fan.

The problem is the furnace control module doesn t use a separate speed when the unit is running in continuous fan mode. For refrigeration evaporator fan motors. There are many reasons for choosing a variable speed furnace but the main reason is comfort. In addition to better energy efficiency and temperature control variable speed furnaces deliver better indoor air quality as a result of varying blower motor speed.

In recent years new furnaces with bpm motors have gained market share. During the cooling mode variable speed systems typically result in an efficiency gain of about 1 seer seasonal energy efficiency ratio. If a variable speed control is used it may attempt to compensate by reducing airflow across the indoor coil resulting in lower efficiency and capacity. The term variable speed furnace is used to describe furnaces that have a variable speed blower motor.

The term variable speed refers to the furnace s fan motor which moves at different speeds to precisely control the flow of heated and cooled air throughout your home. This is not new technology said christopher mohalley master ecm trainer at regal beloit. Running the heating system s fan continuously allows the furnace s blower motor to continue air circulation even when heating is not required. Better airflow control means a better balance of temperature and humidity.

Furnaces without variable speed technology use a simple motor with multiple speed settings. Carrier gas furnaces with greenspeed intelligence monitor temperature and humidity inside and out then automatically vary furnace operation as needed to provide an ideal combination of comfort and energy efficiency. With greenspeed intelligence and variable speed components you can avoid wasting money for heating capacity you don t need. While not all contractors consistently offer ecms those who do often report increased profits as well as improved customer comfort and satisfaction.

These speeds are used by a contractor to adjust airflow to the proper amount. A temperature based variable speed fan control may cause problems especially during defrost cycles. Temperature rise declines as the outdoor temperature drops. These blower motors are the motors that move air through the ductwork in your home.