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Industry Steps up CO2 Training Efforts

         Don Gillis | Lead Technical Trainer

          Emerson’s Educational Services

The use of commercial CO2 refrigeration technology is expected to increase significantly over the next few years. But in the U.S., very few service technicians have experience installing, commissioning and maintaining CO2 systems. I recently contributed to an article in Contracting Business that discussed how our industry is addressing the urgent need for CO2-specific education, training and certification programs.

Compared to legacy hydrofluorocarbon (HFC) systems, CO2 (refrigerant name R-744) has many unique performance characteristics and system properties. Because CO2 refrigeration is still relatively new to the U.S. market, most HVACR trade schools and technical colleges simply haven’t integrated CO2 topics into their refrigeration training programs. But today, that’s quickly changing.

Stakeholders collaborate to develop CO2 curriculum

Original equipment manufacturers (OEMs) and industry organizations are actively trying to bridge this knowledge gap by developing CO2 training curricula and certification programs. As an industry steward of sustainable refrigeration and a provider of fully integrated CO2 solutions, Emerson is helping industry organizations to accelerate these efforts.

We’re collaborating with the North American Sustainable Refrigeration Council (NASRC), the ESCO Group and other industry stakeholders to spearhead the development of the first CO2 curriculum for community college and trade school HVACR programs in the U.S.

According to Morgan Smith, program and communications director at the NASRC, the goal of this collaboration is to integrate a CO2 curriculum into the commercial refrigeration tracks at technical colleges. The new curriculum will cover a wide range of topics to help familiarize technicians with CO2 refrigeration, including:

  • Basic terms and definitions of CO2 characteristics and systems
  • CO2 safety fundamentals, such as: handling, tools and gauges, relief requirements, leak rates and room sensors
  • Core curricula, including: required experience; understanding CO2 as a refrigerant; operating characteristics; types of CO2 systems; working with non-traditional system components, compressor types, control systems and equipment applications
  • Installation procedures: handling CO2 as a refrigerant; installation fundamentals and piping insulation
  • System commissioning procedures
  • Service and maintenance procedures, such as: system charging and discharging; repairing and replacing components; CO2 oil management; CO2 system recovery; defrost methods and custom systems
  • Troubleshooting

“Because CO2 is so new to the U.S. commercial refrigeration market, technicians and end users have varying degrees of hesitation. We hope these training programs will help remove some of the mystery and concerns about using this efficient and environmentally friendly natural refrigerant,” Smith said.

Emerson CO2 training programs

Emerson continues to expand on our CO2-specific training initiatives through our mobile training units and Educational Services programs. In 2019, we introduced our third-generation CO2 mobile training unit to serve Canada and the continental U.S.; to date, it has trained more than 1,000 industry professionals in North America.

This year, we’ll be launching a second CO2 mobile training unit at Emerson Educational Services’ primary location in Sidney, Ohio. Once there, it will become the centerpiece of a two-day training program designed to give contractors, OEMs, wholesalers and end users a hands-on experience of what it’s like to work on a CO2 transcritical booster refrigeration system. As COVID-related health guidelines permit, we hope to send our CO2 mobile training units back on the road to be featured at industry events and provide training where it is needed most.

In addition, Emerson Educational Services currently offers two virtual and in-person training courses related to CO2:

  • Two-day “CO2 Refrigeration” course specifically designed to train technicians
  • One-day course entitled, “Fit for the Future: Working with Natural Refrigerants, A2Ls, and A1 HFO Blends”

The net goal of all these efforts is to give the entire commercial refrigeration supply chain — from wholesalers and distributors to OEMs, end users and service technicians — a greater familiarity and comfort level with CO2 refrigeration. To learn more about the CO2 training programs at Emerson, visit our course schedule, or contact Emerson Educational Services at


Keys to Servicing A2L Refrigerants

         Don Gillis | Lead Technical Trainer

          Emerson’s Educational Services

The refrigerant transition is underway, and HVACR service technicians find themselves at the leading edge. As the commercial refrigeration and AC industries move from high-global warming potential (GWP) hydrofluorocarbon (HFC) refrigerants to lower-GWP alternatives, mildly flammable A2L refrigerants are viewed as viable alternatives. But the technician community is largely unfamiliar with A2L servicing requirements and has many questions that need to be answered. I recently participated in an article for RSES Journal, in which we discussed the emergence of A2Ls and reviewed key servicing best practices. You can also view the article here.

Regulatory efforts to approve A2L refrigerants took several steps forward in 2021. The Environmental Protection Agency’s (EPA) Significant New Alternatives Policy (SNAP) Rule 23 approved R-454B and R-32 for use in residential AC applications, subject to use conditions. In addition, the UL approved the second edition of its UL 60335-2-89 standard that included A2L charge limit guidelines for self-contained and remote refrigeration systems. Although the UL 2-89 update was a major development, more regulatory approvals will be required to roll out A2Ls on a broader scale. Industry stakeholders expect EPA guidance and SNAP approvals for the use of A2L refrigerants in commercial refrigeration to happen soon.

But if you’re an HVACR technician, the chances of encountering A2Ls are on the rise. To maximize safety and assist your customers with installation and service calls, now is the time to gain a better understanding of A2Ls.

Back to basics with best practices

Thankfully, the transition from existing refrigerants to A2Ls won’t require a fundamental shift in the way you conduct service calls. But it will require more rigorous attention to basic servicing fundamentals. Existing recommended best practices for A1 refrigerants will apply — with the addition of a few special considerations and A2L-rated tools.

The potential for flammability makes the use of leak sensors and detection equipment a more important system consideration with A2Ls. Otherwise, A2Ls have very similar characteristics and pressures as common A1 HFC refrigerants, such as R-410A. It’s also important to be aware that some blended refrigerants, such as R-454B, will have a degree of glide.

When installing or repairing A2L refrigerant-based equipment, technicians will need to use A2L-rated gauges and tools and wear proper personal protective equipment (PPE). Compared to A1 procedures, there are some required steps when dealing with A2Ls that are considered best practices for A1 systems:

  • Purge the circuit with inert gas (i.e., oxygen-free nitrogen).
  • Evacuate the refrigerant.
  • Leak-test and pressure-test the unit.

A2L cylinders have the same rated pressure as current R-410 cylinders. To make sure an A2L refrigerant is not mistaken for an A1, A2L tanks have several distinguishing characteristics, including:

  • Pressure relief valve is designed to release only enough refrigerant to reduce the cylinder pressure.
  • Red band/stripe (or the entire top painted red) indicates the presence of a mildly flammable refrigerant.
  • Left-hand (LH) thread indicates the presence of an A2L refrigerant.

It’s important to remember that all HVACR equipment must be designed and rated for the use of A2L refrigerants. As such, A2Ls are not to be used as drop-in replacements for A1s in existing HFC systems. When charging refrigeration systems with an A2L, technicians must ensure that they do not exceed the maximum allowable charge rate.

Look for safety labels on A2L-based HVACR equipment to alert you of additional precautions. Some may also include a panel designed to cover service ports. For more information, please visit the Air-Conditioning, Heating, & Refrigeration Institute’s (AHRI) Safe Refrigerant Transition Task Force website (

A2L training is available

As A2L refrigerants make their way into U.S. AC and commercial refrigeration applications, industry organizations, manufacturers and stakeholders are working together to prepare for their wider adoption. At Emerson, we are actively developing A2L-certified compressors, condensing units and components to support the transition to lower-GWP refrigerants in commercial refrigeration and residential AC applications.

In addition, Emerson Educational Services is developing and conducting A2L training seminars as part of our “Fit for the Future” initiative. To prepare your service team to safely install, service and recover A2L refrigerants, please visit our course schedule.





Selecting Condensing Units for Walk-in Coolers and Freezers

         Don Gillis | Lead Technical Trainer

          Emerson’s Educational Services

Outdoor condensing units (OCUs) have become essential for providing remote refrigeration in the walk-in coolers and freezers (WICFs) used by food retailers, foodservice operators, cold storage facilities and processing plants. As OCU technologies and end-user preferences continue to evolve, contractors need to understand many considerations when selecting an optimal OCU for their specific application and operational requirements. In a recent E360 article, we evaluated key selection criteria and explored today’s leading OCU options.

Sustainability goals, refrigerant regulations and efficiency standards

To help operators comply with environmental regulations and meet their sustainability initiatives, OCU equipment manufacturers are integrating lower-global warming potential (GWP) refrigerants. However, this doesn’t necessarily mean that contractors and end-users will need to adapt to completely new servicing and operating procedures. Many OCUs are designed to use a newer generation of lower-GWP A1 hydrofluorocarbon (HFC) refrigerants — such as R-448A and R-449A — which represent minimal changes in terms of safety protocols or servicing.

But since these lower-GWP A1 refrigerants have degrees of glide, contractors need to be aware of how the sizing and selection process may be impacted. Refrigerants with glide may have a diminishing impact upon system capacity, which might require you to select a slightly larger-horsepower OCU — and unit cooler/evaporator — to meet your refrigeration load requirements.

As safety standards and building codes evolve over the next few years, mildly flammable A2Ls will likely be added to the list of refrigerant alternatives used in OCUs. Today, Emerson is actively qualifying our OCUs for use with A2Ls and will be ready to support operators seeking even lower-GWP A2L options when they are approved.

When it comes to OCU use in WICFs, refrigerants are only part of the sustainability equation. Per the Department of Energy’s (DOE) 2020 rule, WICFs must meet 20–40 percent energy reductions on new and retrofit systems below 3,000 square feet. To calculate the energy efficiency of a complete WICF system, the DOE uses a metric created by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) called the Annual Walk-In Energy Factor (AWEF).

If you are a contractor installing a condensing unit and/or unit cooler, you must ensure this equipment meets or exceeds the minimum AWEF ratings based on capacity and application — such as medium- (MT) or low-temperature (LT); indoor or outdoor; and refrigerant type. To comply with the DOE standard, simply combine a Copeland™ AWEF-rated condensing unit with an AWEF-rated unit cooler.

Copeland outdoor refrigeration units

Copeland outdoor refrigeration units are designed to comply with regulations and provide sustainable refrigeration for a wide variety of modern operator requirements. Combining the reliable efficiency of Copeland scroll compressor technology with variable speed fans, large condenser coils and smart electronic controls, Copeland X-Line Series outdoor refrigeration units provide whisper-quiet performance in compact enclosures, delivering maximum installation flexibility.

Copeland outdoor refrigeration unit, X-Line Series — available in a horsepower range from ¾ to 6 HP, the X-Line is designed for LT and MT applications, such as WICFs and display cases commonly found in convenience stores (c-stores), restaurants, supermarkets and cold storage facilities. It delivers best-in-class energy efficiencies, a slim profile, ultra-low sound levels, superior diagnostics and built-in compressor protection. Offering AWEF-rated efficiencies and lower-GWP (R-448A and R-449A) refrigerant options, the X-Line supports reliable refrigeration while solving many of today’s operational challenges.

Copeland digital outdoor refrigeration unit, X-Line Series — The digital X-Line Series builds upon the field-proven Copeland scroll and X-Line OCU platforms to deliver superior cooling and energy efficiency in MT applications. Providing variable-speed fan motor control, the digital X-Line Series enables variable-capacity modulation to deliver more precise, reliable refrigeration, longer-lasting equipment and lower energy bills. Available in 3, 4, 5 and 6 HP models, the digital X-Line Series also supports multiplex refrigeration architectures — where one OCU provides cooling for multiple fixtures — to meet a variety of modern refrigeration challenges:

  • Reducing the number of refrigeration fixtures and/or refrigeration loads
  • Precisely sizing refrigeration units and loads to an application
  • Eliminating compressor cycling, which negatively affects system performance and equipment longevity
  • Improving food quality and extending shelf life via tighter temperature control
  • Removing constraints that prevent the installation of multiple fixed-capacity OCUs

Calculate the capacity of your OCU

At Emerson, we are committed to helping contractors calculate refrigeration loads and select OCUs to meet a diverse range of LT and MT refrigeration requirements. By selecting the correct OCUs for your customers’ WICF applications, you can ensure reliable, efficient system performance throughout their lifecycles. To simplify this process, Emerson has created a free online Box Load Calculator tool to assist manufacturers and operators to select, purchase and identify the appropriate equipment for their application. Simply navigate to the Equipment Selection tab, enter your application parameters and estimated refrigeration load, and review your optimal equipment options as you evaluate your specific refrigeration requirements.

Refer to Emerson’s Box Load Calculator to help select a condensing unit for your application.










Refrigeration Basics: Addressing the HVACR Technician Shortage

         Don Gillis | Lead Technical Trainer

          Emerson’s Educational Services

Welcome to the fifth and final installment in our blog series intended to help not just beginning service technicians, but anyone who wants to learn more about the basics of refrigeration. In this blog, I explain what we at Emerson and others are doing about the growing shortage of skilled, qualified and certified HVACR technicians in the industry. For this series, we’ve also created companion videos about each topic that you can cross-reference while accessing other related information at

Nearly 40 percent of the jobs available in the HVACR industry are unfilled. That’s about 80,000 good-paying positions for technicians who can install, maintain and repair the critical refrigeration equipment upon which our customers depend. At the same time, our industry loses experienced technicians as aging workers retire and also as the result of normal attrition every year. If we do not hire and train new technicians, our industry could potentially face a deficit of 100,000 workers within the next five years.[i]

That’s one of the reasons I’ve written this series of blogs about refrigeration basics. With the help of others at Emerson, I’ve also created a related set of videos to explain what refrigeration technicians do — and what they must know to be successful in our business. We need more skilled, qualified and certified HVACR technicians. So we’re promoting our educational services, which include instructor-led and online courses.

Emerson also partners with industry organizations and leaders to create learning opportunities through events such as World Refrigeration Day. To mark that day in June, we shared a webinar, Exploring Cool Careers and Emerging Opportunities in HVACR, which showed how refrigeration technicians have a high earning potential and work with advanced technologies and modern tools. You can watch the webinar on-demand.

Young people should consider a career in HVCAR because they can:[ii]

  • Make an impact — Refrigeration technicians implement new environmentally friendly solutions that will play an integral role in making the world a better place to live.
  • Work with cutting-edge tools and technologies — Modern refrigeration and air conditioning applications utilize advanced controls, software and remote diagnostics capabilities.
  • Achieve job security — With little competition for available jobs, HVACR professionals are virtually guaranteed employment and will enter into a field with both long-term security and growth potential.
  • Earn while they learn — HVACR technicians can earn a competitive wage with a two-year vocational certification and have the option to augment the certification process with on-the-job training in apprenticeship programs.

At Emerson, we are committed to recruiting the next generation of HVACR technicians. Our company is addressing the technician gap in three ways by:

  1. Offering courses for upcoming technicians so that they can expand their knowledge of HVACR fundamentals
  2. Recruiting the next generation of HVACR technicians by providing real-life experiences through co-ops and internships
  3. Partnering with industry leaders so that we can brainstorm ways to bridge this gap

The reality is that there’s an abundance of lucrative opportunities for young people who want a long-term career path without the time commitment and cost of a four-year college education. That’s why I’m really excited about the future of the refrigeration industry. Indeed, jobs and training are available to enable people to acquire the necessary refrigeration skills. Emerson is helping in that regard, too. If you’re interested, let’s talk.


Read “Reversing the Trend: Recruiting the Next Generation of HVACR Professionals ” to discover how Emerson is working to make refrigeration technician careers ‘cool’ again.




[i] Rajan Rajendran, “Become a “Cooling Champion” for World Refrigeration Day 2021,” June 26, 2021, Emerson Climate Conversations, (accessed July 20, 2021).


[ii] Rajan Rajendran, “Reversing the Trend: Recruiting the Next Generation of HVACR Professionals,” E360 Outlook, June 2021, (accessed July 20, 2021).



Refrigeration Basics: Understanding the Refrigeration Cycle

         Don Gillis | Lead Technical Trainer

          Emerson’s Educational Services

Welcome to the fourth installment in our series of blogs intended to help not just beginning service technicians, but anyone who wants to learn more about the basics of refrigeration. In this blog, I explain the nuances of vapor injection along with the full refrigeration cycle. For this blog series, we have also created companion videos about each topic that you can cross-reference while accessing related information at

Comparing Refrigeration to a Baseball Diamond

The refrigeration cycle requires four main components. No matter how small or how large a cooling system might be, its design will include a compressor, a condenser, a metering device and an evaporator.

When I teach new technicians, I often compare the refrigeration cycle to the layout of the field for the game of baseball. I’ve found this analogy makes refrigeration equipment and processes easier for them to understand.












In my example, a compressor is located at home plate at the bottom of the baseball diamond (shown above). In a refrigeration or cooling system, compression is the first step:

  • Refrigerant enters as a low-pressure (LP), low-temperature (LT) superheated vapor and exits the compressor as a high-pressure (HP), high-temperature (HT) vapor.
  • The compressor mechanically compresses the refrigerant gas.
  • Under pressure, the refrigerant volume is reduced and the temperature is raised.

The second step involves a condenser, located at first base on the right side of the baseball diamond:

  • Hot, pressurized refrigerant gas arrives from the compressor into the condenser, which is designed to reject heat by lowering or returning the temperature of the refrigerant to its condensing temperature.
  • As it rejects heat, the condenser converts the vapor to a sub-cooled liquid.
  • In most condensers, the refrigerant gas enters at the top of the equipment and leaves at the bottom because the refrigerant in a liquid state is much heavier than the weight of refrigerant in a gas state.

In the third step, a metering device located at second base at the top of the baseball diamond regulates the amount of refrigerant released into the evaporator in response to the cooling load and causes a pressure drop.

The metering device also:

  • Measures the superheat at the evaporator outlet
  • Maintains a constant temperature by raising or lowering the amount of refrigerant flowing into the evaporator

At the fourth step, cold liquid refrigerant mixes with vapor causing the saturation temperature as it boils off or vaporizes in the evaporator, located at third base, on the left side of the baseball diamond:

  • The process allows the refrigerant to absorb heat through a series of metal coils.
  • The low-pressure superheated vapor refrigerant gas then returns to the compressor to continue the refrigeration process.

Here is the value of comparing the refrigeration process to a baseball diamond: If I draw a vertical line from home plate up to second base, everything in the system on the right side of that line is under high pressure; everything on the left side of that line is low pressure.

Likewise, if I draw a horizontal line from first base to third base, the refrigerant above the line is in a liquid state; below the line, the refrigerant is a vapor, regardless of whether it is under high or low pressure.

Liquid Injection Cools Compressor and Increases Capacity

A compressor is designed to operate at very high temperatures, so a liquid injection method has been developed to cool the compressor internally. How this works can be confusing; refrigerant is injected in a vapor state, not in a liquid state.

When necessary, liquid injection cools a compressor to enable it to run reliably under difficult high compression ratio conditions normally seen on low-temperature freezer applications.

  • Refrigerant is piped from the system liquid line, through an injector valve to the compressor; in scroll compressors, the refrigerant is injected directly into the scroll elements.
  • Without this cooling, the compression elements can get too hot and the oil breaks down, leading to compressor failures.

Another approach called enhanced vapor injection (EVI) increases refrigeration capacity and, in turn, the efficiency of the system:

  • A heat exchanger is utilized to provide subcooling to the refrigerant before it enters the evaporator.
  • A small amount of refrigerant is evaporated and superheated above its boiling point.
  • This superheated refrigerant is then injected mid-cycle into the scroll compressor and compressed to discharge pressure.

The diagram below shows how enhanced vapor injection (EVI) increases the efficiency of the system.










EVI increases the compression ratio and, in the process, boosts capacity for the refrigeration system. The greatest gains can be achieved during the summer months and other periods when warm ambient temperatures require more cooling.

View our new video series to learn more about the refrigeration cycle. For a deeper dive into all of our training content and access to our other educational resources, visit

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