Product Knowledge Guide: Walk-in Refrigerators

Walk-in refrigerators and freezers are available in virtually any shape and size. These units can be as small as 15 cubic feet and as large as 400,000 square feet. Multilevel walk-ins also are available. Coolers are more likely to be larger than freezers.

Most walk-ins are custom fabricated, which allows operators to design the unit to best fit their needs. Quick-ship, off-the-shelf walk-ins also are available in set sizes and include either remote or packaged refrigeration systems that contain a condensing unit and evaporator coil all in one housing.

Operators can purchase walk-ins built from a wood frame box, high-density rail or Polyurethane foam. Polystyrene units, which are less energy efficient than foamed-in models, also are available. These units’ exteriors typically feature stainless steel, aluminum or galvanized aluminum construction. Less common architectural finishes, such as aggregate or brick veneer, are available, too. Wall thickness varies from 4 or 5 inches for freezers and 3.5 inches for coolers.

Depending on whether units are coolers or freezers, walk-in temperatures generally range from -15 degrees F to 40 degrees F. Lower temperatures for blast freezing applications are achievable by working with a consultant who specializes in this type of configuration.

Smaller walk-ins typically include a ½-hp compressor and maintain a 35-degree F temperature, while freezers use a 1-hp compressor to maintain a -10-degree F temperature. The larger the walk-in, the greater the horsepower necessary.

A variety of door configurations, including sliding, bi-parting and single styles, are available in electric and manual versions. Doors with windows also are available when visibility into the walk-in is necessary.

Common Applications

  • Operators use walk-ins in numerous ways, among the most common is storing cold or frozen food.
  • Walk-ins with glass doors are common in retail settings and for display merchandising.
  • Custom units serve as merchandisers for beer, wine and other items.

Specifying Considerations

  • Determine what products the walk-in will hold. Depending on an item’s density and temperature, it may take longer to pull down to the correct temperature and a larger refrigeration system may be necessary to compensate.
  • When calculating the necessary capacity, keep in mind that 1 cubic foot of open storage area accommodates  approximately 28 pounds of solid food.
  • Doors are an important consideration, since they receive most of the day-to-day abuse. If doors are frequently opened and closed, heavy-duty doors may be necessary. Kick plates on the door and inside the walk-in are also helpful in preventing damage.
  • Factor in the weight and frequency of traffic when determining what type of flooring is necessary. If staff will use heavy-loaded carts to transport food or if there will be heavy shelving inside, a reinforced or structural floor may be appropriate.
  • For walk-ins with floor panels, interior or exterior floor ramps can provide easier access.
  • Look for a minimum 10-year limited warranty against structural defects.
  • White interior finishes can create a brighter environment and make the walk-in’s contents more visible.
  • In high-acid environments, such as bulk vegetable  storage, marinated products, poultry etc., consider other metals for the interior. Check with a product specialist  for more details on how to select metals for these  environments.
  • The use of low-velocity coils inside a box may be appropriate in certain situations, such as when a unit stores delicate produce or certain dough items.
  • When specifying boxes where transport carts are often used, such as in schools, catering and corrections, specify the appropriate bumper systems so as not to prematurely damage or even puncture walls with handles, hinges, bumpers, etc.
  • Coated coils may be necessary in high-acid environments.

Specifying Mistakes to Avoid

  • Because the load put into a walk-in can dramatically affect the function of the cooling system, take into account the size of the condensing unit and evaporator.
  • Not only do operators need to determine how much product the unit will store but also how often staff will stock the walk-in, which is dependent on the number of food deliveries.
  • Account for the extra clearance these units require. Walk-ins require at least 2 inches of space between the walk-in ceiling and building as well as a minimum of 1 inch on all sides for proper ventilation.
  • Future needs are not always a consideration, but it’s important to determine if space requirements will change or if the operation will need to move the walk-in sometime in the future.
  • Account for the kitchen temperature. If the refrigeration system will operate in a hot environment, a larger size may be necessary.

New & Notable Features

  • Today’s units use CFC-free insulation, which offers improved energy efficiency.
  • Newer technology includes Bluetooth connectivity, which alerts operators when appropriate temperatures are not being maintained.
  • Motion detector lighting ensures that lights are not left on unnecessarily.
  • Temperature monitoring and recording systems can help operators comply with HACCP guidelines.
  • Evaporator controls increase overall efficiency as well as product life and overall maintenance costs.

When to Replace

  • Older, less efficient units:With new and more energy-efficient technologies continuously being developed, experts recommend replacing walk-ins after 15 years of service.
  • Worn exterior: If panel skins are deteriorating or separating from the foam, the walk-in most likely needs to be retired. Interior panel seams that have condensation or frost build up typically signify that the seal is no longer adequate and air is leaking through. This can compromise holding temperatures and necessitate a new unit.
  • >Gaps and air leaks: Door seals and sweep gaskets can be replaced. However, sagging doors that allow outside air into the walk-in can cause ice buildup on the evaporator coil, compromising efficiency and requiring the purchase of a new unit.

Maintenance Musts

  • Make sure the door gaskets are in good shape and replace any that are split or damaged to keep cold air from escaping. Also, make sure the door is level and doesn’t have any gaps that would allow outside air in.
  • Clean cooler walls and floors with a sanitizing solution consisting of 1 part bleach and 32 parts water (4 ounces of bleach to 1 gallon of water). Rinse both with clean water.
  • Regularly wipe ceilings and walls to avoid mildew and bacteria growth.
  • Keep condenser coils clean. If coils become clogged, they will eventually make the compressor overheat, resulting in premature failure of the refrigeration system.
  • There should be no debris buildup that can compromise the door seal.
  • Refrain from using products that can pit, oxidize or  corrode the metals.
  • Do not clean walk-ins with high-pressure hoses or  cleaning systems.

Environmental Advancements

  • Walk-in refrigerators and freezers are not eligible for Energy Star qualification at this time. Energy efficiency ratings for these units are based on R factors, which denote the insulation of the panel. These typically range from R32 to R48, with the higher numbers offering greater insulation.
  • Although more expensive, walk-in panels with foamed-in-place polyurethane insulation offer the best R-value and are the most energy efficient, which can save money over time.
  • Electronic controllers for refrigeration systems with reverse cycle defrost offer the optimum
  • operating efficiency.
  • Energy-saving options include automatic door closers, strip curtains at doors, high-efficiency lighting and high-efficiency motors on condensing units.
  • Alarm/light management systems warn staff when doors remain open too long and automatically turn off lights after a specified time, conserving energy.
  • Electronic and LED lighting introduces less heat into the walk-in, which can reduce the workload on the refrigeration system's compressor and conserve energy.
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