- August 28th, 2012
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.
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. Read the rest of this entry »
- July 13th, 2012
Regardless if you are remodeling or building new stores, why not increase the use of your space and install a beer cave for your alcoholic beverages? Beer caves have grown to be very popular in the convenience store industry offering a bright inviting room for customers to browse their selection. Beer caves can come in any shape or size. They are all custom designed to fit your plans. Consider the advantages the beer cave can provide for you and your customers.
Bright lights, glass doors and windows can make an old drab corner turn into an inviting alcoholic beverage oasis. It is proven that bright lights and colorful graphics grab people’s attention attracting more customers to the product. Customers like to see all their choices right in front of them. The beer cave consolidates all beer and alcoholic beverages in one area so it is easy for people to find what they are looking for, grab and go.
- December 27th, 2011
This article is courtesy of Austin Industrial 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 Read the rest of this entry »
- August 19th, 2010
Are you investing your energy resources wisely? The following tips provide ideas for maintaining an energy efficient operation.
Track energy consumption
Tracking your monthly electricity, water, sewer, trash and natural gas consumption is a first step toward managing your impact and monitoring the effectiveness of efficiency improvements. If you’re an independent operator or local chain, get audits from local utilities and municipalities. Many organizations provide free energy, water and waste audits in addition to advice, technical and sometimes financial assistance for upgrades and program development. Take advantage of these free professional services.
Allow for air circulation around refrigerators and freezers
Refrigerators remove heat from inside the box and eject that heat through the coils on the top or bottom of the unit. When you are cleaning around these units, do not push your reach-ins into tight spaces where the heat will build up, forcing the unit to work harder and use more energy.
Defrost food regularly
Develop a frozen food pull schedule to avoid the practice of defrosting food under running hot water. If a two-gallon-per-minute faucet is used for this purpose one hour every day for a year, the cost may exceed $800. Read the rest of this entry »
- November 6th, 2009
The vinyl door gasket on the inside edge of the door for your walk-in cooler or freezer is very important. It creates a seal the keeps cold air from escaping, which means the unit will stay colder longer and use less energy. Old gaskets wear out and lose their seal. Even worse, older gaskets can pose a food safety risk because they begin to collect grime and food bits and become a breeding ground for bacteria.
Luckily, it’s easy to replace door gaskets! There are several different styles of gaskets. To insure you get the proper gasket, gather the following information:
1. Dimension of gasket – Measure from outside corner to outside corner for both height and width. For Some suppliers prefer the dart to dart measurements (center of gasket) or the door opening size. It’s best to measure several different areas to be sure you receive the correct size.
2. Manufacturer – Get the manufacturer’s name and the model and serial number of the walk-in. The tag containing this information may be in the door jamb or mounted somewhere on the inner frame.
3. Style – Check to see if the gasket is magnetic or non-magnetic(compression). Almost all newer refrigeration equipment will have a magnetic gasket . A magnetic gasket will be hard and square at the point where it contacts the inside frame of the unit. Magnetic gaskets will also snap shut when you hold the door less than an inch from the frame because the magnet attracts to the metal.
Compression gaskets usually need a door latch to hold them tight in place to get a good seal. These gaskets are soft and compress easily at the point where they contact the inside frame of the unit.
Door gaskets are also categorized by how they attach to the door. There are 3 ways a door gasket mounts on a door: snap in (or dart), push in, and screw in.
Read the rest of this entry »
- October 7th, 2009
The following article comes from Dependable Refrigeration, LLC.
Storage of Fresh Food in the Refrigerator
The air in a fresh food refrigerator is always quite dry. What moisture there is in the refrigerator tends to collect and condense on the evaporator surfaces. Therefore, food containers should be covered and as air tight as possible to keep food moist.
The temperature inside the fresh food cabinet should be kept at 35 to 45 degrees F. Most fresh foods may be kept from three days to a week at the above temperatures. Unfrozen meat and fish should be stored at as close to 32 degrees F as possible. Fruits and vegetables should be cleaned and prepared for the table before being refrigerated.
For Storage of Frozen Food in the Freezer
The air in a food freezer, as in refrigerator, is very dry. Any moisture in the air of the freezer quickly condenses on the evaporator coil surfaces. It is very important, therefore, that all frozen foods be packaged in moisture proof containers. Read the rest of this entry »
- February 16th, 2009
KNOXVILLE (WATE) — Knox County health inspectors were forced to temporarily close a North Knoxville deli this week over a walk-in cooler that was way too warm.
When the inspector found the walk-in refrigerator at 60 degrees and not working properly, she ordered a lot of food thrown away including ham, turkey, meatballs, pepperoni, bacon, eggs, and cheese.
Nearly 100 pounds of food were ordered thrown away because they weren’t safe to eat. Garelli’s was closed until the refrigerator was repaired.
Plus, the inspector found a roach crawling on the kitchen floor. Garelli’s pest control company was ordered to pay a visit.
Maybe the roach was attracted to the moldy grapes, celery and rotten tomatoes the inspector found in the refrigerator.
Mold was also found in the ice machine and water was leaking onto the kitchen floor.
Garelli’s is open again.