The Cooler Controllertm: the Brains Behind the System. The Basic Freeaire System has two main components: a model 2001 Cooler Controller with 2 sensors and a Circtm circulating fan. The Cooler Controller is a sophisticated electronic controller featuring: a microprocessor and thermistor temperature sensors. It can be located inside or outside a walk-in cooler, wherever it's convenient, but it must be outside a freezer. It controls the operation of the condensing unit by opening and closing the liquid line solenoid valve found in a typical "pumpdown system." It also controls up to two circuits of evaporator fans, and alternates their use with the Circ fan's to maintain proper airflow. When connected to the optional humidistat the Cooler Controller activates the anti-sweat door heaters during periods of high humidity. It can operate an optional high and low temperature alarm. In cold climates it can also control the operation of the optional Cool Breezetm outside air package that can bring cold outside air into the cooler. It can handle refrigeration equipment of any size either directly with built-in electronic relays called triacs (up to 10 amps @ 120V) or indirectly by using optional mechanical relays for higher voltages and amperages and 3-phase circuits.

Evaporator Fan Control. In a walk-in cooler with a conventional compressor system the evaporator fans operate continuously, 24 hours a day. The evaporator fans need to operate while the compressor runs in order to force air over the evaporator coils and thereby refrigerate the walk-in. After the compressor turns off and the "cold " has been driven out of the coils, these fans circulate the air and equalize the temperature within the walk-in. However, the large amount of electricity these fans consume is sometimes 30 times more than is needed for proper circulation and is simply converted to heat, which results in even more wasted electricity (about 40% in a cooler, and 60% in a freezer) from increased compressor operation. A Freeaire system eliminates this waste by shutting off (after a short delay) the evaporator fans whenever it shuts off the compressor. At the same time, it switches on one or more energy-saving (36 watts), but large volume (550 cfm) Circ fans that take air from the ceiling and push it toward the floor to ensure a uniform temperature throughout the space. The Circ fan below runs more than the six 130 watt evaporator fans behind it using only 1/20th the energy.

On-Demand Evaporator Defrosting. The Freaire's model 2001 Cooler Controller has a clock which initiates evaporator coil defrosting, and a temperature sensor to end it. The second evaporator circuit can be defrosted independently from the first by installing an optional second temperature sensor in that evaporator unit's coils (cooling fins). The Cooler Controller keeps track of the accumulated runtime of the condensing unit. After it has run long enough to cause the evaporator coils to need defrosting (usually about 6 hours of accumulated runtime for a walk-in cooler, or 4 hours for a freezer) a defrost period begins. The evaporator fans run but the condensing unit does not, while a sensor monitors the temperature of the evaporator coils. This air-defrosting continues until the evaporator's temperature indicates that all ice has been removed. If there is a second evaporator circuit with its own temperature sensor, those evaporator fans will operate until their coils are defrosted as well. An optional amount of time can be added here to be sure that defrosting is complete before the defrost cycle ends and the condensing unit can operate again. This open-ended strategy ensures that there is always enough defrost time but never too much. The refrigeration system always operates at peak efficiency because the evaporator coils are regularly kept clear of ice. Unnecessary evaporator fan operation is further reduced and energy saved.

Door Heater Control. Reach-in glass doors usually use door heaters to keep condensation from forming during humid weather, but they are a waste of electricity for most of the year. A Freeaire system can eliminate this waste by automatically switching the door heaters off whenever the relative humidity is low, as determined by the adjustable setting on the optional humidistat (item #550). The humidistat is placed where it monitors the air near the outside of the reach-in doors and the setting is left at that level of humidity at which condensation is not yet a problem. It's quite simple and very effective.

Walk-in Freezer Control. The model 2001 Cooler Controller can now control the refrigeration of a typical walk-in freezer with electric defrost heaters for the evaporator coils. It automatically operates an electric defrost cycle that uses only enough heat to melt whatever frost that has accumulated on the coils, but no more. This is yet one more way for the Freeaire to save energy. Because compressors are less efficient at removing heat from freezers than from coolers, there is even more energy saved when the evaporator fans are switched off for most of the time. In most climates there will be no outside air supplied to a freezer due to the limited amount of time outside air is frigid enough.

Nighttime Warm-up Period. When there are no perishables or dairy products that can spoil without constant refrigeration inside a walk-in cooler, there is often an opportunity to save energy by allowing the temperature of the walk-in to rise to a higher level for a period of time, usually overnight. The model 2001 Cooler Controller's clock allows the operator to select a period of time each day during which the walk-in can be allowed to warm up.

Optional Alarm. The model 2001 Cooler Controller allows the installation of an optional alarm that signals a too-warm or a too-cold temperature inside the walk-in cooler. This alarm can be a blinking strobe light (Item #651) that can be located wherever the person who needs to know can see it. Although the Cooler Controller is highly reliable and not prone to failure, any part of the mechanical refrigeration system can fail, and an alarm can give an owner peace of mind.

Data Download Capability. The model 2001 allows daily, monthly or yearly downloading of runtime percentages for the compressor, evaporator fans, circulating fans, door heaters, and outside air system fans. This provides a much more accurate calculation of the energy savings resulting from the installation of the Cooler Controller than simply comparing monthly electric bills, which include all the ups and downs of electrical usage on the same meter.