NATIONAL REPORT—When shopping for a walk-in cooler or freezer, it pays to be selective. A quick, uninformed purchase can result in unnecessary energy costs down the road. There are a lot of vendors out there. Before you come to a final buying decision, be sure to keep in mind all of the considerations that impact energy consumption.
Insulation is one important factor. It is what provides resistance to heat flow. According to Scott Mallernee, product manager for Parsons, Tenn.-based Kolpak, polyurethane offers the best value. Four inches of polyurethane, he says, provides the same amount of insulation as 8.5 inches of fiberglass, polystyrene or Styrofoam.
Most suppliers produce walk-in wall panels with four to six inches of polyurethane insulation. Kolpak uses a method that involves shooting foam insulation between two metal panel skins to create a tight barrier. Master-Bilt, New Albany, Miss., also uses a foamed-in-place process for its panels.
“It then cures and hardens,” Mallernee says. “You end up with a panel with tight cells.”
For the environment’s sake, be sure to ask about the type of blowing agent that is used in walk-ins that use polyurethane. R-22, because it is not ozone friendly, is being phased out. A non-CFC agent such as 245FA is acceptable.
U.S. Cooler, Quincy, Ill., uses extruded polystyrene in its walk-ins. The company says it holds R-value for a longer period of time than polyurethane. What is R-value? Insulation performance is usually rated in R-value. The higher the R-value, the more resistance to heat flow, therefore the better its insulating properties. Also, the more water resistance insulation has, the better the performance. Water lowers the R-value of insulation.
In California, Mallernee says, the Energy Commission requires an “R” factor of 34 on freezers and 28 on coolers. California also requires five inches of insulation, unlike other states, where four inches is acceptable.
Keep Door Seals Tight
Lynn Burge, advertising and promotions manager for Master-Bilt, says the door is the most important part of the walk-in. If there is not a good seal, performance will be less and energy costs will be higher.
“Make sure that the door is hanging tight and that there are no gaps in the door gaskets,” Burge says.
Mallernee says it is important to change door gaskets regularly. It is also wise to use some type of air curtain, especially in high-traffic situations. Air curtains can be plastic or use blown air across the entrance to keep the cold air in. Some air curtains blow air down from the top of the doorway. Others such as Kolpak’s Air Shield blow air horizontally across the entrance.
Master-Bilt’s optional Master Controller electronic control system, used primarily for walk-in freezers, replaces a lot of the mechanical parts found in traditional systems. The company says it can reduce energy costs by as much as 26 percent. It incorporates reverse cycle technology and eliminates the need for defrost heaters. Additionally, defrost time is lessened. The average time using defrost heaters is 20 to 30 minutes. However, reverse cycle performs a completely “clean” defrost in three to five minutes.
From a preventive maintenance perspective, in addition to checking door gaskets, it is important to keep coils clean.
“The walk-in’s refrigeration system needs room to breathe,” Mallernee says. “You need to be able to draw air across the coils.”
Regularly check temperature as well. Where freezers are used to store ice cream or to freeze items that are not currently frozen, the temperature should stay at minus 20 degrees. Frozen items entering a freezer that are not ice cream can be kept at minus 10 degrees. Cooler temperatures should stay at between 34 to 36 degrees.
Glenn Hasek can be reached at firstname.lastname@example.org.