The Effects of Ambient Temperature on Refrigeration Load Sizing

The key to determining the proper refrigeration load requirement for any box  rests on two general items:

  1. Product load or internal heat load. This would include incoming temperature of product being stored, heat of respiration of product being stored, any change of state of the product (freezing), and any heat given off by lights, motors, people, etc.
  2. External load. This would include any air infiltration load, radiant load through walls, ceiling, floors, etc.

Ambient temperature or ambient temperature difference from external box temperature to internal box temperature can have a significant impact on the load required.

On walk-in coolers for example, the difference in wall and infiltration loads from an 80°F ambient to a 90°F ambient is approximately 18-20%. From an 80°F ambient to a 100°F ambient that difference increases as much as 30%. See table 1.

Table 1

Data from Russell’s Engineering Manual

Table 2

Data from Russell’s Engineering Manual

In all cases, the refrigeration technician should use proper sizing tools such as the Russell Engineering manual RU-ENG-0313A to determine the proper load requirements.

Source: HTPG Tech Note February 2019

Introducing the New U.S. Cooler Walk-in Door.

U.S. Cooler walk-in cooler

Here at U.S. Cooler®, we work hard to bring you a quality product at a reasonable price with exceptional attention to the needs of the customer.  So, with that in mind, starting today, all walk-in coolers and freezers will come standard with our break-through Vert-Ergo™ handle, new adjustable hinges, efficient LED lighting, and a dual-temperature display with touch switch.  Below, we have more information about each of the new products, but what does this mean for you?  In short, our new Vert-Ergo™ handle provides a more ergonomic hand position while increasing your leverage to make opening your walk-in cooler or freezer easier.  The new adjustable hinges allow easy adjustment of door alignment with standard spring-action door closing.  The efficient LED lighting offers a reduction in electrical usage, plus a decrease in heat generation for further savings.  Lastly, the thermometer with built-in light switch offers dual-temperature display with an easy-touch switch, as well as multiple other add-on features for further energy control.  We work hard to ensure that every detail of your walk-in cooler and freezer is built to our superior quality standard and is manufactured with your needs in mind.

Vert-Ergo™ handle

Handle-200x355
  • Vertical handle design for easier opening.
  • Ergonomic positioning for a comfortable feel.
  • Reversible for mounting on either a right hand or left hand door.

LED Light

1808 LED Light
  • Designed to reduce electrical usage by 85%.
  • Minimal heat generation will lower utility cost.
  • Exceeds Federal Energy Act Requirements.
  • Rated for 50,000+ hours of life.

Adjustable hinges

1346 Performer Hing
  • Strap adjusts horizontally, providing door lift and rotation to compensate for unlevel or uneven floors.
  • Built-in spring action is standard.
  • Left and right hand hinges use the same component parts for faster mounting and replacement.

Dual-temperature display with touch light switch

1967-3
  • Dual-temperature display changes between freezer and cooler temperature probes.
  • Designed for (wet & dry) in-door and/or outdoor locations
  • Light relay with touch technology
  • Quick Installation, No connectors required

Refrigeration Solutions for Craft Breweries

brewery countThe craft brewery industry has seen exponential growth this decade, fueled by consumer demand for full-flavored beers. According to the Brewers Association there are 3,040 breweries operating in the U.S., 99% of which are small, independent craft breweries.1 With thousands more breweries in the planning stages, this trend shows no sign of slowing.

The logistics of how to keep beer cold and fresh before shipping to the consumer is vital to the success of any craft brewer. That’s why Brew Cave by U.S. Cooler is introducing their new line of walk-in coolers for the brewery industry. Brew Cave is best known for its walk-in kegerator for residential bars, but now produces everything from keg storage warehouses to tap house coolers.

tapped kegs
Kegs rigged up to supply a tasting room.

Every brewery has unique needs and budgets. Brew Cave’s flexible design process allows them to easily create custom walk-in coolers. Whether the cooler needs to be angled, have reach-in glass doors, operate with minimum sound, be located outdoors or any other special case, Brew Cave is up to the task. Their parent company U.S. Cooler has been in operation since 1986 and its employees have extensive experience catering to a wide assortment of industries from bars, convenience and grocery stores to scientific and manufacturing facilities.

Refrigeration Guidelines for Specific Applications

This article is courtesy of Austin Industrial Refrigeration.

floral storage refrigerator
Flowers do best with High Humidity and Low Velocity refrigeration

Aside from the box temperature, other considerations that are particular to medium temperature applications (walk-in coolers & refrigerators) are the air velocity and humidity of the refrigerated space. Below freezing, humidity is inherent (the moisture is mostly frozen out of the air), so low temp applications are easier to spec than medium temp.

The following are common design parameters and examples of their application:

  • 35 degrees F / 90%+ relative humidity (low velocity coils) – high humidity – Used for: sensitive materials, floral – roses
  • 35 degrees F / 85% – 90% relative humidity – general purpose – Used for: foodservice, fresh meats, packaged goods not sensitive to humidity, short-term mixed produce, thawing, and dry goods unaffected by humidity
  • 35 degrees F / 60% – 75% humidity – low humidity – Used for: retail, beer and beverage coolers, packaged items, materials sensitive to humidity
  •  45 degrees F / 55% – 70% humidity – low humidity – Used for: aging red wine
  • 45 degrees F / 90%+ humidity (low velocity coils) -high humidity – Used for: sensitive materials, floral – general
  • 55 degrees F / 55% – 70% humidity – low humidity – Used for: processing rooms occupied by personnel
  • 55 degrees F / 60% – 75% humidity (low velocity coils) – low humidity – Used for: produce

Size Your Walk-in Refrigeration Unit

When buying refrigeration units for walk-in coolers & freezers, it’s very important that your refrigeration is sized correctly for your box and application. Incorrectly sized refrigeration can result in problems such as the refrigeration unit constantly running and eventually freezing up.

To help you get the right size refrigeration unit, Heatcraft Worldwide Refrigeration has put together a Quick BTUH Load Calculation Chart. It can be used for walk-ins rooms from 6’ X 6’ X 8’ to 40’ X 40’ X 8’ and with holding temperatures of -20°F, -10°, 0°, 30° and 35°. Loads are calculated based on boxes utilizing 4” of urethane R-25 insulation.

heatcraft refrigeration chart
Click here to view the Refrigeration Sizing Chart

Before using these charts, get this information about your walk-in cooler or walk-in freezer:

1. Room information:

•Length, width, and height of the box in feet

•Holding temperature of the refrigerated room (°F)

•Relative humidity in the refrigerated room (if specified)

•Summertime design ambient temperature (°F). This is usually the temperature expected at the location of an air cooled condensing unit which cools the room

2. Insulation information:

•Type of insulation, insulation thickness (inches), and external temperatures on walls, ceiling, and floor.

3. Infiltration load information:

•The temperature (°F) of the entering air and the relative humidity of the entering air. Also, an estimate of the door usage – average, heavy, etc.

•Does the box have glass doors? Dock doors? How many?

Commercial Refrigeration Maintenance

I’m Mitch Byrne. I have been working in the Refrigeration Trade for over 16 years. I know from experience that commercial refrigeration maintenance can extend equipment life by years & save big on electrical consumption. This article will explain the importance of Commercial Refrigeration Maintenance. It will also outline basic DIY Maintenance as well as professional clean & checks done by a contractor. It is possible for equipment owners to perform some basic maintenance tasks between contractor visits.

Commercial Refrigeration Maintenance is critical, especially when it comes to Walk-In Coolers, Freezers & Ice Machines. This is especially true when it comes to line coolers. All refrigeration needs to expel heat. The majority of units do this through an air cooled condenser coil. This is done by drawing air through the coil. This causes dust & debris to form fairly quickly on the condenser coil. Failure to clean condenser coils on a regular basis will increase electrical consumption & lead to major system component failure such as burnt wiring, a failed condenser fan motor, a restricted metering device or a failed compressor. These are some, but not all of the possible consequences of lack of maintenance. Without a doubt poor maintenance will decrease the lifespan of equipment & increase electrical consumption.

There are things you can do between contractor clean & checks that can really help. The following is a checklist of tasks you can perform to help extend the life of your commercial refrigeration equipment.

  1. Visually inspect the condenser coil on self contained refrigeration. Often the condenser coil is behind a cover at the top or bottom of commercial coolers & freezers. Condenser coils can also be located at front right or left on a unit & also at the back of a unit.  The condenser cover can usually be removed with a Philips screw driver. Occasionally a ¼” or 5/16” nut driver is needed to remove cover. Pictured are a couple types of coolers & condensers.restaurant commercial refrigerators

Diagnose Walk-in Cooler & Freezer Refrigeration Problems

A systematic approach to walk-in cooler and freezer maintenance is the technician’s best guide.

The ubiquitous walk-in cooler or freezer is an essential part of many cafeterias, restaurants and convenience stores. It is also a large energy user in these facilities but is rarely considered until problems emerge.

Problems include failure to maintain pressure and compressor failure, both of which can result in expensive losses to the products stored in the cooler. These problems, as well as unnecessarily high energy use, can be avoided by observing equipment and taking corrective action.

Evaporators
Moisture from the air freezes onto the evaporator coils (the cooling coils in the freezer) and forms an insulating barrier to heat transfer. Airflow also decreases as the passages narrow due to ice buildup. Each evaporator has a defrost cycle to melt frost/ice that has built up on the evaporator coils. Water from the melted ice is drained from the freezer . . . ideally.

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.