Making Sense of Reach-in Refrigerator Jargon
If you've ever had a conversation with a salesperson or a service technician about your reach-in refrigerator, you've likely heard words like "evaporator fan," "capillary tube," and "temperature recovery." Of course you're less concerned with those technical terms than you are about whether your equipment is going to keep doing its job, but with a few key terms in your vocabulary, you're better able to care for your equipment and avoid costly breakdowns and service calls.
The job of any refrigerator is to remove heat from its insulated cabinet and bring temperatures down to the temperatures below 42 degrees Fahrenheit that are appropriate for slowing down the growth of bacteria in food, thus extending the length of time that it can be kept safe to eat. Several components work together to accomplish this.
Refrigerant is the substance that circulates through the system to carry heat from inside the cabinet to the air outside. Historically, a number of different chemicals have been used as refrigerant. You may hear any or all of them referred to generically as "Freon," but that word is actually a trade name for several refrigerants made by the Chemours company, which spun off from Dupont in 2015. Refrigerants are officially named with a system that prefixes each type with an "R" - R-134 and R-290, for example.
Most traditional refrigerants are manmade, lighter-than-air chemicals composed of hydrogen, carbon, and a halogen gas or two like chlorine and fluorine. The first major generation of refrigerants to be widely used in refrigeration equipment was comprised of CFCs (chlorofluorocarbons) like R-12 and R-22. All CFC molecules contain chlorine, which were found to damage the Earth's ozone layer when released into the atmosphere. As a result, CFC refrigerants were phased out in the United States during the 1990s and early 2000s for most non-industrial applications.
The chemicals that were designated to replace CFCs are known as HFCs (hydrofluorocarbons). HFCs like R-134a and R-404a contain hydrogen in place of CFC's chlorine, which means they don't have the same ozone-damage potential as their predecessors. Unfortunately, HFCs have been found to be powerful greenhouse gases that can trap thousands of times more heat in the atmosphere per volume than carbon dioxide. For that reason, the United States government announced in 2015 that foodservice equipment manufacturers must phase out HFC refrigerants from most of their products by 2019.
The EPA-approved refrigerant that most manufacturers have chosen is R290a, which is simply a form of propane, the common fossil fuel that powers the grills and mobile heaters we're all familiar with. Unlike its synthetic predecessors, R290a refrigerant has no potential to deplete the ozone layer and contributes hundreds of times less to global warming. Its molecular structure consists of only hydrogen and carbon - that's why it's sometimes referred to as a "hydrocarbon refrigerant".
The move to hydrocarbon refrigerant has benefits beyond protecting the environment. Equipment designed for R290 refrigerant operates at a lower pressure than its predecessors, so it's likely to provide longer equipment life since it puts less wear and tear on refrigeration components. Equipment that uses hydrocarbon refrigerant also tends to be more energy efficient than traditional equipment, so operators who switch to using hydrocarbon equipment are likely to save on their utility bills.
The Condensing Unit
The term "condensing unit" actually describes a group of components that includes a reach-in's compressor and condenser coil. This unit is always located on the outside of a refrigerator's cabinet. The compressor is a mechanical component that drives refrigerant through the refrigerator's system, and it's named for its role in compressing refrigerant, changing the substance from a gas to a liquid and priming it to release its stored heat.
Once it's been compressed, refrigerant passes through a condensing coil, a long, thin, winding copper tube. The condenser is designed to provide a wide surface to transfer the refrigerant's heat into the surrounding air. The copper tubing is surrounded by hundreds of tiny fins that serve to draw heat away from the refrigerant. A fan blows air over the coil to lend further efficiency to the process.
Condensing Unit Location
Another concept you're likely to encounter when you're exploring your refrigerator options is top-mounted vs. bottom-mounted condensing units. We cover this topic in-depth in our top- vs. bottom-mounted condensing unit article, but we'll list the major advantages of each here.
In bottom-mounted refrigerators:
- Components are easily accessible for cleaning and maintenance.
- The condenser operates away from the higher temperatures near the ceiling.
- Components are less likely to be affected by greasy air that migrates toward the ceiling.
In top-mounted refrigerators:
- Components are not exposed to dirt and dust on the kitchen floor.
- Heat from the reach-in condenser does not rise into the cabinet.
- More cabinet space can be dedicated to holding products.
The counterpart to the condensing coil is the evaporator coil, which is always located in the top of the unit. Like the condenser, the evaporator is comprised of a long, winding tube– used to enable the refrigerant to absorb heat from the equipment's cabinet. Refrigerant is in a gaseous state while it's in the evaporator, and an evaporator fan blows air over the coil so it cools the cabinet evenly and efficiently.
As the reach-in's evaporator pulls heat out of the air in your refrigerator's cabinet, it causes moisture in that air to condense into liquid water. Because the temperature of the evaporator coil itself is below freezing, that liquid water will turn into ice. To prevent the resulting ice from building up to a level that could cause problems for your equipment, the system will periodically enter a defrost mode.
Manufacturers employ a number of different methods to defrost the evaporator coils. One of the most common is the hot gas defrost system, which reverses the equipment's refrigeration cycle so that the evaporator coil warms up, melting the ice that has collected there. An alternative to the hot gas cycle is the electronic evaporator heater, which melts ice with an electric heating element attached to the evaporator coil. Hot gas systems tend to take less time and electricity, but the extra stress that they put on the refrigeration system by taking the coil from cold to hot in a short period of time may shorten the equipment's life.
You may see manufacturers describe their equipment's defrost systems as time-initiated, temperature-terminated. That phrase simply means that the defrost system starts automatically according to a timer and ends when the system has reached the proper temperature to melt all of the ice that has collected. An alternative to this system is the time-initiated, time-terminated defrost cycle. This simpler system is usually less expensive up front, but can lead to the defrost cycle lasting longer that necessary and wasting electricity.
Of course, manufacturers must also include some method to handle the water that results from the defrost process. That water is generally piped into a condensate pan underneath the refrigerator, where a heating element encourages it to evaporate. These systems are often coupled with wick systems designed to expose the water to air and speed the process of evaporation.
A commercial refrigerator will enter its defrost mode automatically, usually three or four times a day. Many refrigerators also include manual defrost modes, but those are generally only needed while the equipment is being serviced. If you feel that your equipment is entering its defrost mode too frequently or not frequently enough, consult a service technician, who may be able to adjust the defrost timer to perform more efficiently.
Capillary Tubes vs. Expansion Valves
Every refrigerator must include a mechanism that meters the amount of refrigerant allowed to flow into the evaporator coil. This mechanism ensures the refrigerant is able to efficiently absorb heat. Two types of metering device exist for this purpose.
The capillary tube is the simplest type of metering device, and refrigerators built with them tend to be the most affordable. A capillary tube is simply a thin tube that meters refrigerant by responding to pressure changes within the system. Refrigerators with capillary tubes are good at maintaining steady temperatures, but less so at bringing down products from warmer temperatures. For that reason, refrigerators with capillary tube systems should only be loaded with product that is already at the proper temperature, like those that you transfer from a walk-in cooler.
Thermal expansion valve systems, often abbreviated TXV, are more sophisticated and capable of responding to changing conditions. They're adept at bringing room-temperature products down to holding temperatures. For this reason, many industry experts recommended that an expansion-valve refrigerator be used when an operator needs a "working box" - that is, a refrigerator that will be frequently accessed in high-demand areas such as those in the hearts of commercial kitchens.
Look at the specs for virtually any commercial refrigerator and you're likely to see the words "foamed-in-place" to describe how the equipment is insulated. This term describes how insulation is blown into the equipment's cabinet from a pressurized chamber, forming a dense, rigid mass that prevents heat from passing through the refrigerator's walls.
A well-insulated cabinet minimizes the length of time that the refrigeration system has to run, saving energy and keeping your equipment in service longer. Another benefit to adequate insulation is that it reinforces the cabinet's structure. Thick insulation can help protect the machine's cabinet from dents and dings, and keep the frame from sagging so that the doors and other essential structural components continue to fit properly for the life of the equipment.
Refrigerator Temperature Recovery
"Recovery" is a refrigerator's ability to bring its cabinet temperature back to the set point after an event occurs that introduces heat into the cabinet, such as the door being opened or someone placing room-temperature food into the cabinet. A unit that is said to have good recovery will bring the cabinet back down to the correct temperature in a short amount of time.
In order for equipment to keep food safe from the microorganisms that cause foodborne illnesses, it must reduce the time interior temperatures are in the "danger zone" between 41 and 139 degrees Fahrenheit. Equipment with poor recovery may allow food to drift into that range where pathogens can develop and affect the safety and quality of food.
Another benefit of quick temperature recovery is that the equipment won’t run for an excessive period of time. Shorter run times translate to lower energy consumption and reduced wear and tear, so the equipment is likely to last longer and require fewer service calls over its lifetime.
The Importance of Maintaining a Clean Refrigerator
Take care of your reach-in and it will likely continue to serve you for years without the need for much maintenance. Equipment that is bogged down with grease and dust has to run harder to reach the right temperature, wasting energy and risking a breakdown when the strain becomes too much for the system to handle.
A single service call can cost hundreds of dollars, not to mention the additional cost of whichever parts may need to be replaced. To help cut down on the need for those calls, perform the following maintenance chores periodically. For a full list, see our guide to commercial refrigerator maintenance.
- Keep the condensing coil clean. Since the condensing coil is the part of the refrigeration system that's responsible for getting rid of heat, it must be kept clear of dust in order to do its job. Maintaining a clean reach-in condenser is necessary to keep your warranty intact, as well.
- Clean the cabinet. Keeping your refrigerator's cabinet clean, inside and out, will prevent it from rusting and pitting, potentially extending the entire equipment's lifespan. Not only that, but you'll help protect your customers by eliminating the bacteria that could potentially contaminate food held in and near your refrigerator. Make sure to use the appropriate cleaner for the surface you're cleaning. Exposing certain metals to harsh chemicals can do more harm than good.
- Check the gaskets for wear and tear. Your refrigerator's gaskets are responsible for sealing warm air out of the cabinet. Over time, they can become worn, loose, and cracked, allowing warm air to seep in from outside and forcing the refrigerator to work harder than it should have to in order to keep the equipment cool. A popular test of a gasket's quality involves closing the door with a dollar bill between the gasket and the cooler. If the dollar falls out, the gasket has become worn and should be replaced. Follow the refrigerator manufacturer's specifications for cleaning and lubricating the gasket to keep it in service for longer.
Reach-in Refrigerator Materials
Refrigerator manufacturers employ a number of different materials to build their equipment. Specific combinations vary from manufacturer to manufacturer and from model to model, but here are some of the common metals and their applications.
Aluminum is the most lightweight and inexpensive metal that goes into building refrigeration equipment. Manufacturers routinely build the back, side, and top panels of their cabinets out of aluminum. Because it is a softer metal, aluminum is more prone to denting and scratching than other materials, but that isn't generally a problem since aluminum surfaces are not exposed to passing traffic. One major advantage to aluminum is that it doesn't rust like steel and iron, no matter how badly it is abused.
Aluminum can be given a finish that closely matches stainless steel, so that setup provides a cohesive look while allowing the equipment to be sold at a competitive price. Reach-in refrigerator interiors are also frequently constructed of aluminum. Manufacturers employ a number of methods to enhance the durability of aluminum interiors. Some apply a clear coating to the material while others paint it. Painted aluminum interiors tend to be white. Each of those coatings help make the aluminum easier to clean and more resistant to scratching.
Galvanized steel is an affordable version of steel that has been coated in zinc to give it rust-resistant properties. Galvanized steel is the least attractive of the three main metals. It has a dull, blotchy finish that makes it a poor choice for building exterior components that will be exposed. However, galvanized steel does make a durable and economical choice for components like refrigerator tops, bottoms, and backs. It's a choice that allows manufacturers to keep costs low without sacrificing durability.
Stainless steel is the most durable material used in the manufacture of commercial refrigerators. Stainless is strong and resistant to scratching, denting, and bending. It's also highly resistant to rust, which is important in commercial refrigerators, since they're often exposed to moisture and acidic products. Most standard-duty equipment will be built with stainless steel fronts and interior floors, the two surfaces that see the most abuse from life in the kitchen. Heavy-duty reach-in refrigerators are usually built mostly or entirely of stainless steel. Such equipment is often specified in institutional settings and especially high-volume kitchens.