ECM Retrofit Best Practice:

Dirty Coil vs. AirRevive Rejuvenated Coil

 Case Study 

EC Motor energy consumption before and after AirRevive Coil Rejuvenation

CUSTOMER: Full Service Hotel


LOCATION: Philadelphia, PA


INDUSTRY: Hospitality


AIRREVIVE SERVICE: Fan coil unit refurbishment and re-commissioning


Make: IEC

Model: 4CH315

Configuration: Horizontal

The purpose of this study was to determine how coil condition impacts EC motor performance and energy consumption.


The process was the following:


Compare the same hotel guest room fan coil unit’s performance under 3 different conditions:

A. Fan coil unit with PSC motor and uncleaned coil.

B. Electronically commutated motor (EC Motor) retrofit into the unit with uncleaned coil.

C. EC motor retrofit after coil was rejuvenated. i.e. an AirRevive rejuvenated coil.

Comparison Data

Energy Consumption

Data  taken on high fan 450 CFM:



Fan coil unit with PSC motor; impacted coil



EC motor retrofit into unit with impacted coil



EC Motor retrofit into AirRevive rejuvenated coil

RPM 1375 1580 1220
Watts 119 110 68
Amps3 1.10 .03 .03

Watts were reduced by 38% when the EC motor was retrofit into an AirRevive rejuvenated coil compared to an EC motor on a dirty coil.

Watts Before and After AirRevive Rejuvenation

PHL watts

EC Motor RPMs to achieve same airflow

Dirty coil vs. Rejuvenated coil



The energy savings are twofold:


1) In the differential in the RPM, which is visible.


2) In the reduced resistance, which is the lowered torque. This is essentially invisible but is manifest in the reduced energy consumption numbers.


The EC motors are torque sensitive.  The EC motor on the dirty coil required a higher RPM to get the motor to perform according to its program, i.e. 1580 RPMs. The motor worked harder to overcome the dirty coil. To maintain constant RPM, the EC motor senses the resistance and automatically increases torque. The EC motor adjusts torque to maintain constant velocity.  This increases power consumption.


The clean coil requires 30% less RPM to produce the same 450 CFM airflow i.e. 1220 RPM. Additionally, the motor draws less torque because the clean coil has less resistance. The motor does not have to work as hard.



Rejuvenating the coil is the best practice to retrofit an EC motor. This study shows that retrofitting EC motors  into fan coil units with AirRevive refurbished unit with rejuvenated coils result in reduced energy consumption.