standard size walk-in

Operating Costs for Walk-In Coolers and Freezers

Before purchasing your walk-in, you may be wondering how much it will cost to operate your walk-in.

Estimates for Standard Sized Walk-ins

To give you a rough estimate of how much it cost to operate a walk-in cooler or freezer, using the national average of $0.1071 per kilowatt, look at the chart below.

Cooler Average Cost per month Freezer Average Cost per month
6×6 $70.74 6×6 $244.13
6×8 $70.74 6×8 $244.13
8×8 $126.49 8×8 $244.13
8×10 $119.30 8×10 $372.27
8×12 $119.30 8×12 $372.27
10×10 $151.07 10×10 $372.27
10×12 $151.07 10×12 $435.66
Note: The above figures are estimates in a controlled environment; your exact numbers will vary.

*These numbers were figured using the 12-month rolling average of $0.1071 kilowatt hour cost. According to the Energy Information Administration this is the average cost in the United States for commercial electricity as of November 2014.

This chart was created using several assumptions that can affect your actual operating cost.

  1. The type of insulation in the walk-in.
  2. Efficiency of the refrigeration system.
  3. Inside and outside temperature of walk-in.
  4. Where the walk-in is located.
  5. The temperature and the weight of the product entering the walk-in.
  6. How often the door is opened.
  7. The age of the walk-in.
  8. Cost of electricity.

This is just to name a few. If you would like to be more accurate using your electric rate, follow the instructions below.

Troubleshooting Defrost Problems

When troubleshooting walk-in freezers, technicians often find a frozen evaporator coil. Although there are several possible causes, one common cause involves the defrost system. For some reason, the system is not properly defrosting the evaporator’s coil on a regular basis. In order to effectively troubleshoot this problem, a technician must understand the design and operation of the defrost systems typically used.

frozen evaporator coil
A frozen evaporator coil from improper defrosting.

One popular method of defrosting walk-in freezers is the electric defrost system. This is comprised of several components, including a defrost timer, resistive heater(s), defrost termination switch, fan cycling control, and drain line heater. An electric resistance heater is placed on the outer surface of the evaporator’s coils. The energized heater supplies enough heat to completely defrost the coils.

The resistive heaters used on a typical electric defrost system are sized to provide sufficient heat to effectively defrost the coil’s surface. Their capacity is normally rated in watts per foot. They are shaped to fit snugly onto the coil surface, creating efficient heat transfer during defrosts.

Most heaters are manufactured for a specific coil, and when replacing these heaters it is best to obtain the OEM replacement. Universal defrost heaters are available, but matching their wattage and shape may be difficult.

A defrost timer controls the entire defrost operation. It initiates the defrost cycle, controls the operation of the compressor and defrost heaters, and is part of the defrost termination. Defrost timers can be adjusted to initiate defrost from just once a day to several times a day.

The actual number of defrosts per day depends upon the location of the walk-in. Walk-in freezers are usually designed to defrost once or twice a day. The more humid and warm a location, the more defrosts will be needed. If a system needs to be defrosted more frequently, add only one additional defrost period at a time and monitor the results. Adding too many defrost periods will not be beneficial to the system or the customer.

In a common wiring diagram for a time-initiated, temperature-terminated electric defrost system the time motor (TM) is energized continuously. Normally closed contacts 2-4 of the defrost timer are wired in series with the compressor and the evaporator fan motor (EFM). Normally open contacts 1-3 are wired in series with the electric defrost heaters and the timer release solenoid (TRS).

The timer motor controls the operation of contacts 2-4 and 1-3. They work opposite each other. When contacts 2-4 are closed, 1-3 are opened. When contacts 2-4 are opened, 1-3 are closed. When the timer motor initiates a defrost, contacts 2-4 will open and 1-3 will close. This stops the compressor and the evaporator fan motor, and energizes the defrost heaters.

EC Motor Start-up Issue

Electronically Commutated Motor AO SmitAs of January 1, 2009, all walk-in manufacturing companies must sell their refrigeration units with Electronically Commutated (EC) motors. EC motors lower energy costs and significantly improve the walk-in cooler or freezer performance. These energy efficient motors are offered as a complete unit or as a drop-in replacement. Whichever your use is, if you are not familiar with the EC motor it may seem odd when you initially start it up.
When starting an EC motor, the motor must know where the rotor is located in order to start and continue to run. When power is first applied to the motor, the controller will apply a gradually increasing amount of current to all three windings in the motor over a period of 2 seconds. This will cause the rotor to move to a known location. This move will range from no movement at all if the rotor has stopped in the location needed for the next start or may be a much larger movement if it was a longer distance  from where it needed to be. With a fan blade attached, it may even overshoot and move backwards to get to the right location. After that 2 second “positioning” period the controller will start applying power to different phases in a slow rotating pattern that increases in speed over the next 2 seconds until the rotor is moving fast enough for the controller to be able to detect its location. This second phase of the start cycle usually happens so quickly that you cannot really see what is happening. Within 3 to 5 seconds of applying power, the motor should appear to be running normally, but during those first 2 seconds the movements may seem as though the unit is having troubles starting or is broken.

New Refrigeration on Used Walk-ins – Is it EISA compliant?

The Department of Energy (DOE) has written their interpretation on compliant refrigeration vs. non-compliant refrigeration on walk-in coolers and freezers. Below, DOE explains that any component added to a previously installed walk-in cooler or freezer and manufactured after January 1, 2009, must meet EISA guidelines. This is a draft document and comments and suggestions must be submitted to the Department of Energy prior to February 20, 2012.

The Interpretation from the Department of Energy (DOE)

This is a draft document and does not represent a definitive view of the agency on the questions addressed.

This and other guidance documents are accessible on the U.S. Department of Energy, Energy Efficiency & Renewable Energy web site at:

Guidance Type: Conservation Standards, Enforcement
Category: Commercial Equipment
Product: Walk-in Cooler and Walk-in Freezers
Guidance Version: DRAFT
Issued: January 20, 2012
Comment Period Closes: February 20, 2012

Q: What are the relevant dates for compliance with the prescriptive requirements for walk-in coolers and walk-in freezers? For example: If a newly manufactured component of a walk-in cooler or walk-in freezer is installed in a walk-in box manufactured prior to January 1, 2009, does it have to comply with the prescriptive requirements of 10 C.F.R. § 431.306?

A: The following is a draft U.S. Department of Energy (DOE) guidance document regarding commercial walk-in coolers and walk-in freezers. This draft guidance document represents the Department’s interpretation of its existing regulations and is exempt from the notice and comment requirements of the Administrative Procedure Act. See 5 U.S.C. § 553(b)(A). Therefore, the Department is accepting comments and suggestions from the public until February 20, 2012. Comments and suggestions should be provided in WordPerfect, Microsoft Word, PDF, or text file format by sending an email to WICFEISA2007Guidance-2012-0001{at} Please also include the docket number EERE-2012-BT-STD0001.

At the end of the comment period, this draft guidance document may be adopted, revised or withdrawn.

Craft Brewery Finds Chilling Solution


Sun King Brewery, like many other craft brewers, is located in a downtown area. There isn’t much space for a condensing unit, and complicating the situation further was the fact that the arrangement of the building didn’t allow for the unit to be at the back of the building. It needed to be right in front, next to the walk-in space, and within close proximity of the main parking and front entrance. A discreet solution was critical.
Another important feature for Sun King’s refrigeration system was the reliability. Hundreds of barrels of beer are stored in this walk-in cooler. For a small enterprise, protecting that investment is a business critical issue.


U.S. Cooler, a manufacturer of walk-in coolers and freezers, met with Sun King Brewing about their walk-in cooler needs. Once they understood the demanding requirements of the applications in terms of efficiency, reliability, sound, and discreet look, they immediately recommended the Copeland Scroll™ Outdoor Condensing Unit XJ Series.

Shortly after installation, the refrigeration system was not working. A quick check of the XJ onboard CoreSense™ Diagnostics indicated that there were no compressor or unit issues.

The servicing contractor was able to quickly pinpoint the problem at the evaporator and get the system back up and running. Since start-up, the system has been running flawlessly with no interruption to refrigerating the product. The chart below shows the sound level of the XJ condensing unit compared to a typical outdoor condensing unit.sound decibels


copeland scroll condenser Two six-horsepower Copeland Scroll Outdoor Condensing Units (XJ) were installed 50 feet from the front door by the main parking stalls, a noise- and sight-sensitive area.
• Built-in CoreSense Diagnostics have helped protect the investment since September 2010 with no system downtime.
• Sun King Brewing is planning an expansion requiring more walk-in cooler space. One more XJ unit has been speced out for the job.

2- Sound values shown represent the XJ unit’s lowest and highest operating dBA measurements, or typical industry outdoor unit published data, for both MT and LT products. Sound pressure values are 10 feet from the unit at 25F evap for MT and -10F ambient. A sound reduction of up to 3 dBA will occur in ambient temperatures below 70F. This data is typical of “free field” conditions for horizontal air cooled condensing units and may vary depending on the condensing unit installation. There are many factors that affect the sound reading of a condensing unit such as unit mounting, reflecting walls, background noise and operating condition.


The Copeland Scroll Outdoor Condensing Unit XJ Series ranges in size from 1.5-6 HP, and offers energy savings of up to 40% compared to standard industry condensing units, making it perfectly suited for many walk-in cooler and freezer applications. The XJ Series unit incorporates multiple advances in refrigeration as standard features into a single unit solution, including:
• The latest generation Copeland Scroll refrigeration compressors which have been optimized for the highest annual energy efficiency
• Ultra-quiet and efficient variable-speed PSC fan motors
• Large condenser coils for more efficient heat transfer
• High efficiency fan blade design
• Proprietary electronic algorithms to optimize energy performance
• Exclusive Enhanced Vapor Injection (EVI) circuit on low temperature units for added capacity and system efficiency
• Exclusive CoreSense™ Diagnostics to enable faster, more accurate service, along with compressor protection benefits to lower total lifecycle costs
The XJ Series unit’s slim profile, light weight, wall mount
capability, and sound reduction features may also offer
customers added benefits from:
• Crane rental savings
• Flexible location options previously not available
• Ease of installation and service savings
• Compliance with noise ordinances
• A more attractive and quieter atmosphere for neighbors and customers

Learn more about the Copeland Scroll Outdoor Condensing Unit at:

View the original Quantifiable Business Result PDF

Compressor Amperage Ratings

This article is courtesy of Coldtronics Inc. manufacturers of HVACR alarm systems.

When diagnosing a problem on a compressor, measuring its amperage draw is part of determining if the compressor is performing properly. How does a service technician know the correct amperage draw? The best way to determine the correct amperage draw for a particular compressor is by referring to the rating chart for that compressor.

Compressor manufacturers will publish a rating chart for each compressor they manufacture. These charts can be published in either a table or graphic format. The compressor chart will list the correct amperage draw for the compressor under its various operating conditions. To use the chart the service technician must know the evaporating temperature, condensing temperature and voltage applied to the compressor. By using the chart, a service technician can determine the correct amperage draw for the compressor and use that information to accurately troubleshoot it and the rest of the system.

Obtaining these charts can be a little time consuming, but the extra time involved is worth knowing the correct amperage. With the use of the Internet this information is now a little easier to obtain. Most compressor manufacturers will stamp an amperage rating on their compressor. They will usually stamp the rated load amps (RLA) of the compressor. However, the service technician cannot use this value to determine the correct operating amperage. RLA is a mathematical calculation required to meet Underwriters Laboratories Inc. (UL) approval only.

Refrigeration History: Then and Now

–Philip J Reed, on behalf of Redstone College

Chances are you’ve recently pulled a soda or cold drink of water out of the fridge without giving it much thought. Maybe you dodged summer heat by heading to your air conditioned home. These refrigeration luxuries have done a great deal to change modern living, but avoiding a sweltering day or keeping food cool for consumption later hasn’t always been so easy.

Early Days

jocob perkins refrigerator
Jacob Perkins Refrigerator Photo: Xtimeline

Jacob Perkins created the “first practical refrigerating machine” in 1834, according to the Environmental Protection Agency, and the unit used ether in a vapor-compression cycle. A refrigeration machine in 1850 relied on water and sulfuric acid as a refrigerant, while still others in later years used ammonia, methyl chloride, sulfur dioxide, and other highly toxic, flammable substances. Needless to say, accidents with these machines were common.

And the refrigerators weren’t widely used. Even in the early 20th century, people usually had to get produce fresh daily and consume it almost as quickly. They made frequent trips to the butcher’s shop, and the milkman completed daily rounds. Fortunate people who had the money to spare for weekly ice deliveries were able to keep food for two or three days in an icebox.


Fred W. Wolf created the first commercially successful electric home refrigerator, which was produced in the United States and went on sale in 1913. Wolf’s creation, dubbed the Domelre, was an air-cooled unit made for mounting on top of an ice box. In 1915, Alfred Mellowes worked in a backyard wash house to design another electric refrigeration unit, but this one differed in that a compressor sat in the bottom of the cabinet.

Refrigeration and Freezing for Food Preservation

Because food is so important to survival, food preservation is one of the oldest technologies used by human beings. There are many different preservation techniques commonly used today, including:

  • Refrigeration and freezing : Canning : Irradiation : Dehydration : Freeze-drying : Salting : Pickling : Pasteurizing : Fermentation : Carbonation : Cheese-making : Chemical preservation
frozen raspberries
A bag of frozen vegetables will last many months
without spoiling.

The basic idea behind all forms of food preservation is either:

  • To slow down or completely stop the activity of disease-causing bacteria
  • To kill the bacteria altogether