WSU Energy Program Logo
Bonneville Power Administration Logo
  • Home
  • About
  • Database
      • Browse
      • Energy Systems
        • Building Envelope
        • Electronics
        • HVAC
        • Irrigation
        • Lighting
        • Motors & Drives
        • Multiple Energy Systems
        • Power Systems
        • Process Loads & Appliances
        • Refrigeration
        • Transportation
        • Water Heating
      • Sector
        • Agricultural
        • Commercial
        • Industrial
        • Residential
        • Utility
  • TAG Portal
      • 2017 Residential Lighting TAG (#14)
      • 2016 Multifamily Building TAG (#13)
      • 2015-1 Commercial HVAC TAG (#11)
      • 2014 Residential Building TAG (#10)
      • 2014 Commercial Building TAG (#9)
      • 2013 Information Technology TAG (#8)
      • 2013 ALCS TAG (#7)
      • 2012 Smart Thermostat TAG (#6)
      • 2012 LED Lighting TAG (#5)
      • 2011 Energy Management TAG (#4)
      • 2010 HVAC TAG (#3)
      • 2009 HVAC TAG (#2)
      • 2009 Lighting TAG (#1)
  • Webinars
    • Webinar Archives
  • Glossary
>

Summary

Evaporator Fan Controllers

Evaporator Fan Control: Automatic Two-Speed Control vs. Constant Speed

An evaporator fan controller monitors refrigerant flow or compressor drive motor amps and reduces the speed of evaporator fans when the compressor is off. Especially useful for walk-in coolers and freezers.

Synopsis:

The founders of Energy Control Equipment, Inc., manufacturers of the Frigitek controllers, were motivated by an awareness of how much waste heat is created by evaporator fans in walk-in coolers.  They started developing their first single-phase controller in 1998. This technology became commercially available in 2001. Since then, they have developed a three-phase model (in 2005) and an "ECM" model (in 2008 -- for ECPM [Electronically Commutated Permanent Magnet] motors, also known as ECMs [Electronically Commutated Motors]). 

All three controllers work on the same basic principle.  They monitor refrigeration flow in the system.  When refrigeration is not flowing, they slow the evaporator fan down to reduce fan energy and reduce the extra load on the compressor caused by excess heat given off by the fan when it is running.  Fan control is achieved through reducing the voltage supplied to the fan motor.  As the controller reduces fan motor voltage from 115 V down to 20 V (in a single phase application) the motor speed is reduced from approximately 1,600 RPM down to as low as 400 RPM (E Source, 2005).  Expected savings depend heavily on the run-time of the existing compressor:

  • If run-time is 10%, energy savings from this technology can be 50% or more of overall refrigeration system energy.
  • If run-time is 20%, energy savings may be closer to 25%.

In a U.S. Department of Energy (US DOE), Federal Energy Management Program (FEMP) test, savings varied widely, from 13% to 59%, but generally the off-time was about 2 to 2.5 times the percentage savings. For example, compressor off time before installation of 31% yielded 13% savings.

Energy Savings: 30%
Energy Savings Rating: Comprehensive Analysis  What's this?
LevelStatusDescription
1Concept not validatedClaims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.
2Concept validated:An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.
3Limited assessmentAn unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline.
4Extensive assessmentAdditional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions.
5Comprehensive analysisResults of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.
6Approved measureProtocols for technology application are established and approved.
Simple Payback, New Construction (years): 1.4   What's this?
Simple Payback, Retrofit (years): 1.4   What's this?

Simple Payback is one tool used to estimate the cost-effectiveness of a proposed investment, such as the investment in an energy efficient technology. Simple payback indicates how many years it will take for the initial investment to "pay itself back." The basic formula for calculating a simple payback is:

Simple Payback = Incremental First Cost / Annual Savings

The Incremental Cost is determined by subtracting the Baseline First Cost from the Measure First Cost.

For New Construction, the Baseline First Cost is the cost to purchase the standard practice technology. The Measure First Cost is the cost of the alternative, more energy efficienct technology. Installation costs are not included, as it is assumed that installation costs are approximately the same for the Baseline and the Emerging Technology.

For Retrofit scenarios, the Baseline First Cost is $0, since the baseline scenario is to leave the existing equipment in place. The Emerging Technology First Cost is the Measure First Cost plus Installation Cost (the cost of the replacement technology, plus the labor cost to install it). Retrofit scenarios generally have a higher First Cost and longer Simple Paybacks than New Construction scenarios.

Simple Paybacks are called "simple" because they do not include details such as the time value of money or inflation, and often do not include operations and maintenance (O&M) costs or end-of-life disposal costs. However, they can still provide a powerful tool for a quick assessment of a proposed measure. These paybacks are rough estimates based upon best available data, and should be treated with caution. For major financial decisions, it is suggested that a full Lifecycle Cost Analysis be performed which includes the unique details of your situation.

The energy savings estimates are based upon an electric rate of $.09/kWh, and are calculated by comparing the range of estimated energy savings to the baseline energy use. For most technologies, this results in "Typical," "Fast" and "Slow" payback estimates, corresponding with the "Typical," "High" and "Low" estimates of energy savings, respectively.

Status:

Details

Evaporator Fan Controllers

Evaporator Fan Control: Automatic Two-Speed Control vs. Constant Speed

An evaporator fan controller monitors refrigerant flow or compressor drive motor amps and reduces the speed of evaporator fans when the compressor is off. Especially useful for walk-in coolers and freezers.
Item ID: 147
Sector: Commercial
Energy System: Power Systems--Metering
Technical Advisory Group: 2009 HVAC TAG (#2)

Synopsis:

The founders of Energy Control Equipment, Inc., manufacturers of the Frigitek controllers, were motivated by an awareness of how much waste heat is created by evaporator fans in walk-in coolers.  They started developing their first single-phase controller in 1998. This technology became commercially available in 2001. Since then, they have developed a three-phase model (in 2005) and an "ECM" model (in 2008 -- for ECPM [Electronically Commutated Permanent Magnet] motors, also known as ECMs [Electronically Commutated Motors]). 

All three controllers work on the same basic principle.  They monitor refrigeration flow in the system.  When refrigeration is not flowing, they slow the evaporator fan down to reduce fan energy and reduce the extra load on the compressor caused by excess heat given off by the fan when it is running.  Fan control is achieved through reducing the voltage supplied to the fan motor.  As the controller reduces fan motor voltage from 115 V down to 20 V (in a single phase application) the motor speed is reduced from approximately 1,600 RPM down to as low as 400 RPM (E Source, 2005).  Expected savings depend heavily on the run-time of the existing compressor:

  • If run-time is 10%, energy savings from this technology can be 50% or more of overall refrigeration system energy.
  • If run-time is 20%, energy savings may be closer to 25%.

In a U.S. Department of Energy (US DOE), Federal Energy Management Program (FEMP) test, savings varied widely, from 13% to 59%, but generally the off-time was about 2 to 2.5 times the percentage savings. For example, compressor off time before installation of 31% yielded 13% savings.

Baseline Example:

Baseline Description: Constantly Operating Evaporator Fan
Baseline Energy Use: 3854 kWh per year per unit

Comments:

Assume a shaded pole motor drives an evaporator fan.  The measured operating parameters are 6.4 Amps, 115 Volts for a motor with a typical power factor of 0.6.  Input power is thus 0.44 kW (E Source, 2005).  Assuming constant operation, this fan uses 3,854 kWh annually. 

Manufacturer's Energy Savings Claims:

Savings Range: From 20% to 40%

Comments:

Estimates of energy savings range from 20% to 40% according to Green Power Management, distributors of the Frigitek evaporator fan controller.  The Madison Energy Group (apparently a Frigitek distributor) states that  "all of the electrical power which is used by the fan motors ends up as heat inside the refrigerated space. By operating the fans at a low speed when no cooling is called for, and at high speed only when the system is actively cooling the refrigerator, much less heat is introduced into the refrigerator. Although this results in an additional saving in evaporator fan motor energy consumption, the reduction in fan motor heat generated causes a significant reduction in refrigeration operation, saving enough energy at the compressor to almost double the savings provided by the electronically commutated permanent magnet (ECPM) motor with controller alone".

Best Estimate of Energy Savings:

"Typical" Savings: 30%
Energy Savings Reliability: 5 - Comprehensive Analysis

Comments:

The main variable that savings depend on is the existing run-time of the compressor. The lower the run-time, the more savings this measure will achieve. Many compressors are oversized, and compressor run-time can be as low as 10-20%, making this technology very cost-effective in those cases.  These technologies reduce fan speed when cooling is not required and operation is only for destratification.  Typical propeller evaporator fan speed is 1550 RPM.  A controller reduces voltage to slow the fan speed to only 550 RPM so that air circulation is maintained and stratification doesn't occur.  At this reduced speed, the affinity laws indicate that the fan drive motor would require only 4.5% of full-load power.  In reality, fixed losses limit the reduction in power draw to only 15% to 25% of full-load power (Energy Ideas Clearinghouse, 2004). 

Energy Use of Emerging Technology:
2,697.8 kWh per unit per year What's this?

Energy Use of an Emerging Technology is based upon the following algorithm.

Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))

Technical Potential:
Units: unit
Potential number of units replaced by this technology: 15,730
Comments:

This technology is appropriate for walk-in coolers at supermarkets, restaurants, grocery and convenience stores, liquor stores, cafeterias, ice cream parlors, floral warehouses, produce warehouses, wine cellars and laboratories (E Source, 2005).  They work best in walk-in coolers of 800 cubic feet or larger that have a single thermostat and a dedicated compressor with "on/off" refrigeration system control with shaded pole evaporator fan motors. 

PECI estimates a population of 7,864 walk-in coolers in the Pacific Northwest (From: PECI presentation to the Regional Technical Forum (RTF) staff on Sept 28, 2010, "LED Case Lighting in Vertical and Semi-Vertical Open Refrigerated Cases and Evaporator Fan Motor Controller (ECM) for Walk-In Coolers and Freezers").  It is not known what percentage already are equipped with ECPM motors with or without controllers, but an ECPM evaporator fan motor in the 1/20 to 1/10 hp motor size range would tend to have an input watts requirement of about 50 Watts versus the much larger requirement for low efficiency shaded pole motors.  Since a cooler might have two to four or more fans, the total number of fan drive motors is estimated at 4 x 7,864 x 0.5 = 15,728 fan motors (Note: the 0.5 accounts for coolers that have already retrofitted their old inefficient shaded -pole to ECPM motors).   

Regional Technical Potential:
0.02 TWh per year
2 aMW
What's this?

Regional Technical Potential of an Emerging Technology is calculated as follows:

Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)

First Cost:

Installed first cost per: unit
Emerging Technology Unit Cost (Equipment Only): $141.00
Emerging Technology Installation Cost (Labor, Disposal, Etc.): $0.00
Baseline Technology Unit Cost (Equipment Only): $0.00

Comments:

The retail cost of a Frigitek motor controller is about $325.  The labor cost to install the controller is about $80/hour times 3 hours or $240.  Total cost for controller installation is $565, with each controller controlling about 4 motors.  Thus the cost per motor installed is $141.  (All costs are in year 2010 dollars).  From: PECI presentation to the Regional Technical Forum (RTF) staff on Sept 28, 2010, "LED Case Lighting in Vertical and Semi-Vertical Open Refrigerated Cases and Evaporator Fan Motor Controller (ECM) for Walk-In Coolers and Freezers".   

Cost Effectiveness:

Simple payback, new construction (years): 1.4

Simple payback, retrofit (years): 1.4

What's this?

Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.

Reference and Citations:

WSU EEP, 12/29/2008. Product & Technology Review: Frigitek Controller
Washington State University Extension Energy Program

RTF, 12/11/2012. Commercial: Grocery - Walk-in Evaporator Fan Shaded-Pole Motor Controllers
Regional Technical Forum

RTF, 11/11/2012. Commercial: Grocery - Walk-in Evaporator Fan ECM Motor Controllers
Regional Technical Forum

Sharon Shapiro, 01/09/2011. How To Reduce Energy Consumption in Refrigeration Equipment
The Daily Energy Report

E Source E Source, 01/01/2005. Evaporator Fan Controllers
Platts/McGraw Hill Companies

Energy Ideas Clearinghouse, 09/01/2004. Product and Technology Review: ENS FanSaver
WSU Energy Program

Rank & Scores

Evaporator Fan Controllers

2009 HVAC TAG (#2)


Technical Advisory Group: 2009 HVAC TAG (#2)
TAG Ranking:
Average TAG Rating:
TAG Ranking Date:
TAG Rating Commentary:

Contact
Copyright 2023 Washington State University
disclaimer and privacy policies

Bonneville Power Administration Logo