Preventative Maintenance for Refrigeration Systems

Refrigeration systems are critical in the food service industry. It is very important to practice preventative maintenance on your cooling systems to help prevent them from clogging or breaking down, which could lead to spoiled food, rotten food, etc. The following guidelines are provided from Heatcraft’s Operation & Instruction Manual.

bohn refrigeration unit
Check all fan blades for signs of stress or wear. Replace blades that are worn, cracked or bent.

By following these preventive maintenance steps, it does not guarantee your unit will not break down. However, by taking care and maintaining your refrigeration systems your unit is less likely to have problems.

Unit Coolers

At every six month interval, or sooner if local conditions cause clogging or fouling of air passages through the finned surface, the following items should be checked.

1) Visually inspect unit

• Look for signs of corrosion on fins, cabinet, copper tubing and solder joints.

• Look for excessive or unusual vibration for fan blades or sheet metal panels when in operation. Identify fan cell(s) causing vibration and check motor and blade carefully.

Hard to Open Doors and Pressure Differences in Your Walk-in Box

Improper fixes to hard-to-open doors can cause ice and frost build-up, water dripping on
floors, freezing around door seals and unusual icing patterns in and around the refrigeration equipment.

Nature’s Basics

The physical nature of air causes a cooler or freezer to have a negative pressure compared to the outside air. This is due to the contraction of the air as the temperature drops. The pressure of the air in a sealed box will decrease by 0.3 psi for every drop in temperature of 10 degrees Fahrenheit.
Note: This negative pressure is not caused by the refrigeration equipment removing air. The evaporator fans just cool the air and push it around the box. They don’t have any exhaust venting or “makeup air” being brought in from the outside (like they do in air conditioning systems).

Check it Yourself

The most dramatic pressure change happens when the door is closed. Warm air that entered a cold freezer will be cooled within seconds by contact with the ceiling, walls and product. If the average air temperature quickly drops from 40 to 30 degrees, the pressure drops by 0.3 psi. That’s 43 pounds per square foot, over 800 pounds of force on a normal size door. The door will be impossible to re-open until the pressure is equalized.
Note: The bigger the size of the door and the more airtight the box, the more dramatic it will be.

Copeland Scroll Outdoor Condensing Unit

Copeland now carries outdoor condensing units for the food service industry. There new light weight, slim shaped units are available in medium and low temperatures ranging from 2 – 6 horsepower.

Copeland Scroll Outdoor Condensing Units are perfectly suited for walk-in cooler and freezer applications. All units integrate the many benefits of the Copeland Scroll compressor technology, fan speed control and Copeland Performance Alert™ diagnostic controls, and are available in 208/230 single-phase and 208/230 three-phase voltage applications.

copeland scroll unitScroll compressors offer the highest energy efficiency levels to lower energy bills. With integrated controls that optimize fan motor speed to maximize the heat transfer through over-sized condenser coils, additional energy savings are achieved. The average energy savings for end-users is $350 per year for a 3HP medium temperature unit, however this number could be greater depending on the application.

Types of Refrigeration Systems Used in Walk-Ins

Refrigeration systems consist of a condensing unit and an evaporation coil. The condensing unit is located outside the walk-in and the evaporator is located inside the walk-in. The compressor compresses gas to a liquid. The liquid is then pumped through the condensing unit coil while a fan blows outside air through the coil. Gas is condensed to a liquid and is then pumped through a small copper pipe into the walk-in to the evaporator coil. There, through the expansion valve located in the evaporator coil the liquid is allowed to expand back into a gas. The expansion of the liquid to a gas causes a rapid chilling of the evaporator coil. Since heat always flows toward cold, inside the walk-in air is blown across the evaporation coil to let the coil absorb heat from inside the walk-in. The gas is then allowed to exit the walk-in through a larger copper pipe to the condensing unit where it is once again compressed and cooled to a liquid state and returned to the evaporator coil inside the walk-in. There the cycle is started over.

The new EISA law requires all new walk-ins be equipped with high efficiency motors to be compliant. These cost a little bit more but save you money in the long run. Some suppliers may try to sell you non EISA compliant refrigeration systems. To be compliant with the law and purchase the best lifetime value always ask for EISA compliant equipment.

Refrigeration System Types

1. Remote Systems – Remote systems are the least expensive systems to purchase. They consist of a condensing unit, evaporator unit and misc. parts such as expansion valve, site glass, dryer, pump down solenoid thermostat, and on freezers a timer and drain heater to install the system. They require the use of a licensed refrigeration installer since they are pumped down and charged with refrigerant gas on site. The installer will also charge for any other parts needed for the install such as copper pipe, pipe insulation, connectors, and electrical. They are less expensive systems to buy with the walk-in but may cost more over all depending on what the going hourly rate is with the installer and the cost of the parts he provides. They also provide an advantage by allowing the condensing unit to be located outside the building. There the condensing unit can dump its heat without adding extra heat to the building and air conditioning systems.

Own a restaurant? Tips to save time, energy, and money.

1. Make Your Menu More Efficient.

Are your menu items being prepped and cooked as efficiently as possible? Items that need to be thawed for daily food service can be defrosted in a refrigerator overnight instead of under running water reducing energy usage and conserving water. Review your menu to see if there are common ingredients or items that can all come from one source. Minimizing the number of individual deliveries you receive weekly will add to your conservation practices and reduce your delivery expenses as well as receiving time when you can be going in and out of cold storage using additional energy to bring it back to safe temperatures.

2. Switch to energy efficient light bulbs.

Subway recently switched all their light bulbs to energy efficient bulbs in all of their 2000 US franchise locations. Switching to an energy efficient light bulb can save up to $22 per bulb per year. This can add up to quite a savings over time. Also keep lights off when you don’t need them. If you don’t start serving lunch until 11 o’clock there is no reason to turn the dining room lights on until then.

Areas such as walk-in coolers or your dry store room don’t need to be illuminated all day long. Turning off lights as you leave typically unused areas is a great way to save money on your energy bill. Electrical timers can be used in these areas especially if they are commonly forgotten and left on overnight.

Higher efficiency bulbs can be used in areas that require constant lighting. Replace incandescent lights in your walk in cooler with fluorescent or LED lights which produce less heat and consume less energy. Replacing bulbs with higher efficient options will show a lower cost in your monthly bill.

3. Pre-cut and freeze many of the common vegetables you use in your restaurant or cafe.

slicing-veggiesOnions: Buy in bulk and on sale. Peel and slice or dice. Freeze one layer thick on a cookie sheet. When frozen transfer to plastic jars with screw on lids. Immediately put back in the freezer. Don’t forget to label the jars! When you need some onions in a cooked dish just shake out what you need. If they clump together shake really hard to loosen. Some of the ways we use frozen onions: sautéed or grilled on hamburgers, in omelets, in any dish that the customer asks for “extra onions” that will be cooked or at least heated.

4. Train your staff.

kitchen staff for restaurantTeach your staff to sort recyclables, turn off lights, and let you know if there is a leaky faucet in the wait station. Ask them to bring in their own take-home containers instead of using the restaurant take-outs.

Busy kitchen staff may often forget to do the simplest of energy efficient steps. Leaving oven doors open releases vast amounts of heat. Each time you open an oven door the temperature can drop by as much as 25o F.; watch the clock and use a timer instead. Don’t leave the convection oven or steamer door open too long or it will just continue to release heat, burning unnecessary energy to retain the proper cooking temperature.

The walk-in cooler is another door that needs to be shut at all times or cooling becomes a continuous energy pit. If doors such as the walk-in cooler are consistently left open, place spring hinges on the doors and it will automatically close, eliminating the opportunity for staff to forget to shut the door.

Plan Now for Upcoming Changes in Refrigerants

Be aware that prices of R-22 refrigeration may increase while supplies will likely wane. After January 1, 2010, original equipment manufacturers will no longer be able to sell equipment using R-22. The phase out of R-22 will be a lengthy process and market conditions may not be as greatly affected by the volatility that resulted in refrigerant price hikes characterized by the phase out of R-12.

Existing equipment using R-22 can continue to be serviced with R-22. However, chemical manufactures will no longer be able to produce R-22 after January 1, 2020. After 2020 the servicing of existing equipment will rely exclusively on re-claimed and recycled supplies of R-22.

If your equipment is more than ten years old, you may save significantly on your cooling energy cost by replacing it with a new more efficient model using R-404a or Scroll compressor technology.

Energy efficiency, system performance, hourly run time of equipment, reliability, and actual cost to operate (amp draw, run time, etc.) should be considered when deciding to purchase new equipment.

To help speed the transition away from ozone depleting refrigerants, choose a system that uses ozone friendly refrigerants.

An energy saving experiment for your grocery store

A research study at Kettering University in Michigan investigated how to make an open refrigerated display case (like those found in grocery stores) operate more efficiently.  The study concluded that raising the temperature setting while lowering the air velocity from the refrigeration would not only provide energy savings, but the food was actually kept cooler.

Lower infiltration [of warm air] means the air is coming out at a lower velocity, said Navaz. “Previously, air came out of the upper vent (or grille) of a specific display case at 90 feet per minute. We calculated the optimal speed as 65 feet per minute as an optimal discharge air velocity to yield lower infiltration rate,” he said.

By reducing the velocity by 30 percent, infiltration was reduced by 12 percent and the power required was reduced by 13 percent.

Increasing the temperature at the discharge air grille by about 1 degree (F) and lowering the velocity of air resulted in lower suction pressure at the compressor inletwhich reduced the compressor usage and therefore less energy consumption.

Infiltration represents 83 percent of the cooling load and is the biggest draw on energy of refrigerated display cases. Less energy use translates into real cost savings to the tune of about $13 million for the state of California alone, according to Navaz.

In addition to energy savings, lowering the pressure on the compressor also extends the life of the compressor and creates more cost savings over the long term.

Click here to read the entire Kettering refrigeration study.

Energy Efficient Copeland Scroll Compressors for Walk-ins

Copeland Scroll Refrigeration Compressor

Save valuable resources with energy efficient Copeland Scroll compressors, permanent split capacitor motors and electronically commutated evaporator motors on your next refrigeration system purchase. Scroll condensing units are available for medium and low temperature refrigeration applications. The condensing units are optimized to work with HFC refrigerant R-404A, a reliable alternative to HCFC R-22. As the energy efficiency trend increases, the use of scroll compressors is a more important feature than ever before. Scroll compressors are inherently more reliable because they have significantly fewer moving parts and handle liquid slugs and debris more effectively. The scroll technology has only three moving parts, as compared to the standard hermetic compressors that have 150 plus moving parts. Scroll is effective in using less energy or amp draws verses the standard hermetic compressor. Copeland studies indicate that up to a 15% reduction in energy use is experienced for most applications. When adding the benefit of PSC motors on condensers and EC motors for evaporators, energy use will decrease. Sizing refrigeration equipment to operate for 14 to 16 hours instead of the traditional 16 to 18 hour run time will also save energy by using less kilowatts and costing less to operate compressors and motors.