The Freeaire Manual

Specifying Planning Installing Wiring Controller Logic Commissioning & Troubleshooting Maintaining

Wiring a Freeaire System

WIRING CAUTIONS!

  1. The installer of the electrical wiring of a Freeaire Refrigeration System must be a trained, experienced electrician.
  2. Read these installation instructions carefully before attempting to install, wire, or operate any of the components of the Freeaire system. Failure to comply with these instructions could result in personal injury and/or property damage. Retain instructions for future reference.
  3. Follow all local electrical and safety codes, the National Electric Code (NEC) and the Occupational Safety and Health Act (OSHA).
  4. WARNING: Hazard of electric shock! Several disconnect switches will need to be disconnected before installation or servicing.
  5. Lock and tag power disconnects to prevent unexpected application of power.
  6. Be sure that the power source conforms to the requirements of the equipment.
  7. Fans have moving parts which may cause injury. Do not remove guards.
  8. Do not use the Freeaire System in an explosive atmosphere.
  9. Be sure that all Freeaire System components are properly grounded.
  10. The Freeaire Cooler Controller is not suitable for use in wet locations. If the walk-in cooler is a wet location, mount the Cooler Controller in a separate dry location and run the wiring into and out of the walk-in through liquidtight conduit.*
  11. All wiring that penetrates the inside surface of the walk-in cooler must be airtight and watertight.*
  12. All wiring must have strain-relief connectors where it connects to the Cooler Controller and all other components.
    Electrical wiring can be done after any holes have been cut and all the components mounted. When the walk-in is a dry location, we recommend flexible or rigid, PVC or metal, liquid-tight conduit and connectors, with insulated #12 AWG,THHN, stranded copper conductors to connect all Freeaire System 120 volt connected components. However, you should check your local codes before you begin.
*Keep moisture out: The Caution warnings #10 and #11 deserve some further explanation. We use liquid-tight conduit and connectors to run wires from the intake and exhaust fans (located on the far side of the wall, ceiling, or floor) to the weatherproof electrical boxes located on the intake damper and exhaust housings inside the walk-in cooler. Use electrical paste or silicone caulk to seal out air movement into the walk-in cooler through the inside of the liquid-tight conduit. This is important, because warm, humid, summer air coming through an unsealed conduit will cause condensation inside the electrical box which might even fill with water because of the liquid-tight gaskets, causing shorting and a very unsafe condition! Conduit that connects one of the weatherproof boxes with other boxes inside the walk-in may not have to be liquid-tight because a walk-in cooler is not usually considered a wet location. The Freeaire Cooler Controller is not watertight or approved for use in a wet location, and therefore should not be used where water will be encountered, such as from spray from a hose. Be careful not to locate the Cooler Controller underneath things like evaporator coils, evaporator drip pans and drain tubes. Do not put the controller under an intake damper housing or exhaust fan housing as these may drip some condensation in the summer if the summer plug is left off. When wiring either the intake or exhaust fan, orient it to keep moisture from entering the fan electrical box. When mounted on a wall, locate the electrical box on the exhaust or intake damper housing on the top, never on the bottom. Also orient the intake fan so that its electrical box is on the side or the top, never on the bottom. If moisture were to enter the ducts, fans or housings, it could then easily drain out without coming into contact with the wiring. Always connect the green grounding wire to each fan grounding screw.

Wiring Options: The Cooler Controller is designed to control the compressor system, the door anti-sweat heaters, the outside air system, the freezer defrost heater and the alarm. It is set up to bring both the hot and the neutral wires directly from the 120 volt service, and then distribute this power to the various loads. It is possible, however, to bring power to some of the components first, and then just run a "switch leg" to the Cooler Controller. This applies generally to all of the circuits, but not to the Cooler Controller circuit or to the evaporator circuit #1. The neutral wire is easier to supply to the components on these circuits along with the switched "hot" wire. How you choose to wire the Cooler Controller will depend on what wiring is already in place, and what is the simplest, safest, and most economical method. The diagram of the power board below shows all the possible connections to the Cooler Controller.

Cooler Controller Circuit: This circuit supplies power to the Cooler Controller itself, each of the outside air intake and exhaust fans, and to the compressor control, usually the 120 volt coil of a liquid line solenoid valve. This 10 amp circuit has enough capacity to power up to 6 intake fans @ 150 watts each, 6 exhaust fans @ 36 watts each, and a 15 watt solenoid valve. Using different fans with different amperage draws will affect the number of fans that can be powered directly with the Cooler Controller. If the number or size of the fans to be controlled causes the load to exceed 10 amps, the controller circuit can be used to energize the coil of an appropriately-sized relay or contactor. Because the intake and exhaust fans always switch on and off together, both fans can be energised from the same set of contacts. This can save wire in some instances.

Although the Cooler Controller serves as the compressor system's thermostat, it is not a switch like a simple thermostat. The compressor control contacts don't just close, but energize the control device. We recommend that this device be a liquid line solenoid valve. This makes the compressor system a "pumpdown system" which is generally considered the safest way to protect a compressor that is idle for long periods of time, especially for compressors located outside. This is because refrigerant tends to migrate to the coldest part of the system, and if liquid refrigerant reaches the inlet of the compressor serious damage could result. In those cases in which the compressor is located in a warm inside space it is sometimes acceptable to connect the compressor control contacts to the coil of a relay to control the compressor. Do not connect the compressor control contacts directly to the compressor or to any energized circuit other than the Cooler Controller circuit.

Evaporator Fan Circuits #1 and #2: Each evaporator circuits control up to 10 amps (at 120 volts, single phase) of evaporator fans, but evaporator circuit #1 also controls the operation of all the circulating fans in the cooler. The evaporator fans and the circulating fans never operate at the same time. Unless the Cooler Controller is switched off, either one or the other is operating at all times. This means that up to 10 amps of circulating fans can also be connected to the evaporator circuit #1. However, at 36 watts each that would be more than 33 exhaust fans and would be an unlikely situation.

For evaporator fan loads greater than 10 amps, more than 120 volts, or for 3-phase, use a power relay such as Freeaire items #639, #642, or #657, found in the Catalog of Options. Supply power to the evaporator fan circuit #1's "power in" terminals with "jumper wires" (line and neutral) from the Cooler Controller "power in" terminals. The evaporator fan "power out" terminals will then supply the power to operate the relay's 120 volt coil. This then switches the evaporator fan circuit(s) which are connected to the Normally Open relay terminals.

Door Heater Circuits #1 and #2: These circuits each control the operation of one 120 volt, 10 amp circuit of anti-sweat heaters in the reach-in doors and door frames. When the door heater switch is on, and the humidistat's switch is closed because the humidity is above the humidistat's setting, the Cooler Controller switches on the door heaters. The door manufacturer has probably specified that the door heaters should be on a separate circuit from the product lights on either side of the door openings. However, it is sometimes the case in a retrofit situation that the lights and the heaters are on the same circuit, and it may not be easy to switch off the heaters without also switching off the lights. They should then be rewired so that the heaters can be switched on and off independently of the product lights.

If the door heater load is greater than 10 amps on a 120 volt circuit, you will need to install a power relay in exactly the same way it would be installed in an evaporator fan circuit. See above.

Freezer Defrost Heater Circuit: This circuit is used in a freezer to control the electric heaters used to defrost the evaporator coils. If the defrost heater load is greater than 10 amps on a 120 volt circuit, you will need to install a power relay in exactly the same way it would be installed in an evaporator fan circuit. See above.
Alarm Circuit: The optional alarm (item #651) consists of a 120 V to 24V transformer that operates a 24V strobe light. Mount a 4"x2"x2" electrical box as close as possible to the Cooler Controller and wire a duplex receptacle in series with the alarm contacts in the Cooler Controller. The 24-volt transformer supplied with the alarm can then be plugged into the receptacle to supply power to the strobe light with low voltage wires. The strobe should be located where the flashing light will be seen by someone who can investigate the cause of the too-high or too-low temperature in the cooler, but you will want to place the strobe light where its flashing will not annoy customers.
Low Voltage Wiring - Sensors: The Cooler Controller is supplied with a temperature sensor on a 1' cable and one on a 15' cable, and a sensor on a 30' cable is standard with an Outside Air Package. If any of the three sensor cables is not long enough, an extra-long sensor cable (item #568-xx¹ in Catalog of Options) should be ordered. This special shielded cable is necessary to prevent interference with the signal reaching the Cooler Controller. Simply splicing in plain 3-conductor wire is not satisfactory if a longer sensor cable is needed.

All sensor cables should be wire-stapled, or held by plastic wire clips to the walls or ceiling to ensure that they are protected and out of harm's way the entire path from the sensor to the Cooler Controller.

The inside sensor on the 1-foot cable is installed at the factory and can be attached to the cooler wall just below the bottom of a Cooler Controller mounted inside the cooler, or it can pass through the cooler wall just below a controller mounted outside the cooler. It should be located where it will have good air circulation around it and measure the average temperature of the cooler, not in the path of cold air coming from the evaporators or incoming outside air, and not trapped behind product on a shelf.

The evaporator sensor must be located where it will be encased in the last remaining ice or frost on an evaporator coil during a defrost cycle. This is because, once the sensor is no longer surrounded by ice, its temperature will rise to the ambient air temperature inside the walk-in, and this will cause the Cooler Controller to end the defrost cycle. If there is ice remaining elsewhere on the evaporator coil when the defrost cycle ends, defrosting will be incomplete and the refrigeration system efficiency will suffer. It helps to be familiar with the frosting pattern of the particular evaporator fan units being controlled. If you are unfamiliar with a particular system, ask someone who is, about where frost usually forms. Frost tends to form first, become thickest, and remain longest where the coils are the coldest, often near the refrigerant metering device. Try to insert the sensor between two fins next to a refrigerant pipe by using a large flat-bladed screwdriver to gently pry open a large enough hole. Be careful not to damage the piping. If there is only one evaporator temperature sensor, but there are two evaporator fan units, one of them will usually have more frost buildup than the other, so that should be chosen for the sensor. Do not cut the sensor cable, but coil any excess up, tuck it away and securely attach it, in case it has to be moved to a more frost-prone area later. In a freezer, be careful to keep the sensor and cable away from the electric heating elements to prevent damage to them and to keep the sensor where the ice is last to melt.

The outside sensor, when outside air is used, is usually attached to the screen of the intake wallcap and is run through the intake ducting, intake fan and filter housing, and intake damper as these are installed. Sometimes it makes sense to have the cable take a more direct route from the outside to the Controller. Just be sure that the sensor is measuring the same temperature as the air entering the outside air intake. For instance, do not put the sensor on the south side of a building when the intake is on the north, or vice versa.

Low Voltage Wiring - Humidistat: A door heater humidistat should be located on the wall in the heated part of the building where it will sense the same air as the reach-in doors. It can be above the reach-in glass doors, high enough to discourage tampering or out of the customers' sight in a backroom . Connect it to the Cooler Controller with two-conductor copper thermostat wire.

When the humidistat is first connected, the door heater toggle switch on the Cooler Controller should be switched off. That way, the humidistat can be adjusted to allow door heater operation only after door fogging or sweating has begun to cause a problem.

Wiring Color Code (Suggested for the insulation on the line voltage wiring.)
  • Green - always ground
  • White - always neutral
  • Black - Power to Controller
  • Blue - Outside Air Fans
  • Red - Circ fans
  • Yellow - Compressor Control (solenoid, relay coil)
  • Orange - Evaporator Fans (or to relay coil)
  • Purple - Door heaters (or to relay coil )

Use pairs of any color (but not green or white) to identify a switch leg from a load to the Normally Open contacts of a relay and back. Use this system to easily identify which wire is going to each load as you work inside the electrical boxes. It makes it a pleasant experience for an electrician to know what is going on at all times.

Another Tip: Use a portable spool rack to hold the wires as you feed them into the boxes. It keeps the wires organized and easily accessible.

Specifying Planning Installing Wiring Controller Logic Commissioning & Troubleshooting Maintaining