The Freeaire Manual

Specifying Planning Installing Wiring Cooler Controller Commissioning & Troubleshooting Maintaining

Planning a Freeaire System

Location, location, location: Once you have determined how many of each component there are to be in your Freeaire system you need to decide where each should be located. For any given walk-in, there are usually more than one possible combination of positions for each of the Freeaire components: the Cooler Controller, the Circ fan, the intake unit, the exhaust unit, and the optional door heater humidistat. Below are four different arrangements that work for four different situations. Other combinations of wall- or ceiling-mounted components are possible in each case, and may work just as well as what is shown. Picking a good place for each component means thinking about what requirements that component has for proper functioning, and how the components relate to each other. Remember that you are designing a system, and everything should work with everything else. Look at the factors that need to be considered for each of the components and then pick the locations that make the most sense for your installation. Compromises may have to be made.

The Cooler Controller: The Cooler Controller (item #509 in Catalog of Products) is to be connected by 120 volt wiring in metal or PVC conduit to each of the other Freeaire components as well as the evaporators, compressor control, and door heaters. Temperature sensors need to be properly located and their low voltage wires run back to the Cooler Controller. There may also be a humidistat connected to the Cooler Controller by low voltage wiring.

Pick a DRY location. The Cooler Controller may be inside (drawings #1, 2 &3) or outside (#4) of a walk-in cooler. It may only be mounted outside a walk-in freezer, because the liquid crystal display (LCD) is not liquid at much below freezing. The Cooler Controller is not approved for a wet location, and the National Electrical Code states that some refrigerated warehouses are considered wet locations. Care must be taken to find a location that will always be free from moisture. This may or may not be the case inside your walk-in cooler. A dry indoor location that is outside the walk-in cooler will control each component just as well as one inside the walk-in, but the wiring may be more difficult. The distances from the controller to each of the components may be longer and most of the wiring will have to pass out of the walk-in into the room where the controller is located. Also, an extra-long sensor extension cable (item #568-xx in Catalog of Options) may need to be ordered to allow the Cooler Controller to read the inside temperature from a distance.

Make it accessible, but protected. Place the Cooler Controller where it will be seen on a regular basis by authorized personnel. The display shows information like time and temperatures as well as important warning messages that should not be hidden from the view of those who need to know. You may be justifiably proud of your Cooler Controller and want to show it off, but may not want mischievious customers trying to enter passwords to change settings without your permission or careless deliverymen bumping into it either. About six to seven feet high on the wall between two evaporator fan units inside a typical walk-in cooler or on the wall just outside a cooler or freezer loading door are the two most popular locations.

Sense the right temperature: Whether the Cooler Controller is inside or outside the walk-in, locate it where the inside temperature sensor (which is usually mounted on the wall within 1 foot of the controller) will quickly and accurately measure the air temperature within the walk-in. If the controller is remotely located, this applies only to the inside sensor itself. Do not place the sensor where it maybe blocked by a stack of product and result in a too-slow response time. Avoid placing the sensor directly in the path of the air from the evaporator fans, the circulating fans, or an intake damper housing, since this will lead to a too-fast response time and rapid cycling of the equipment.

Minimize the length of wiring: If the Cooler Controller can be inside the walk-in, locate it near to the other components to minimize the length of conduit and wiring. In an outside air installation a distance of over 30' from the outside sensor (usually located in the intake wallcap) will require an extra-long outside sensor cable which must be ordered separately (item #568-xx). The sensor on the 15 foot cable will usually be used for monitoring the evaporator temperature, so try to locate the controller within 15 feet of the evaporator fans.

The Circtm Fan: (item #531) This is also known as the Downflow circulating fan because it should be centrally located to circulate air down from the ceiling to the floor when the evaporator fans are off. It is to be hard-wired back to the Cooler Controller. Watch the Headroom: The Circ fan hangs down 10" from the ceiling, so it may be tricky to find a good place to install it in a cooler with a low (under 7š6") ceiling.

Upflow Circulating Fan (item #530) This is an alternative to the Circ Fan above. You can see it being used in the L-shaped cooler in drawing #3. It is attached to the ceiling and is connected to dealer-supplied duct pipe, which is attached to a wall. It provides more horizontal "throw" to the air than the Circ fan, but takes up wall space inside the cooler which might better be used for product storage. Sometimes there is a 10" wide space on either end of the reach-in shelves that cannot be filled with product and which is perfect for the upflow fanšs vertical pipe. It is to be hard-wired back to the Cooler Controller. Maximum circulation: The circulating fan housing should be mounted on the ceiling, next to a wall, in such a way that the airflow from it is directed out and across the room to achieve maximum air circulation. Avoid obstacles to the airflow, such as the evaporator fans or shelves. Duct Pipe (Items #518 and #525 in Catalog of Options or bought locally): This 10" x 24 gauge galvanized pipe should consist of an elbow attached to the circulating fan housing and enough straight pipe to extend down the wall and stop about 6" to 12" from the floor, in order to pull the coldest air from the lowest part of the cooler. Locate the pipe where it will not interfere with traffic or product storage inside the walk-in cooler. The back of the elbow and at least the bottom of the straight duct should be firmly attached to the wall with screws.

Humidistat: (item #550) The door heater humidistat should be put above the reach-in doors or somewhere else in the heated portion of the store, so that the relative humidity of the air near the cooler doors can be measured. Once it is adjusted to its optimum setting it should never have to be touched again, so do not make it too accessible to unauthorized tampering.

Cool Breezetm Outside Air Package: (Item #495) consists of two sets of components: those for the intake unit and those for the exhaust unit.

Intake Unit: The intake unit is more complicated than the exhaust because the several components can be mounted in several different orders, depending on the best filter access. The drawings below show various arrangements for the five sections, with a different order in each drawing. Although the drawings show the installations penetrating two walls, the walk-in wall could just as easily be a ceiling, or if necessary, a floor. The wallcaps shown could also be flat roof vents as well.

Intake Damper Housing: (item #538) This is how the outside air enters the walk-in cooler. It can be mounted in a wall, ceiling or floor.

  • Project the air out into the space: The airstream should be able to be directed toward the far end of the walk-in cooler, without being blocked by product or by the evaporator fans. You will be able to feel a noticeable breeze more than 20 feet away, if the airflow is not blocked. Because cold air falls, a position high on a wall will project the air across the room farther than a low position, and be less likely to be blocked by product stacked on the floor. Avoid "short-circuiting" the air directly into the exhaust unit and donšt aim the incoming air directly at a reach-in door. An optional adjustable elbow (item #524) may be attached to re-direct the air by up to 90° in the direction you want. Floor mounting is usually the last choice, as the airflow is likely to be blocked by product on the floor. A 10" diameter rigid duct from an intake damper on the floor to near the ceiling can be used to overcome this problem.
  • Watch the headroom: If the intake unit is mounted from a low ceiling, avoid placing it over an aisle, especially if there is an optional adjustable elbow attached.
  • Avoid obstructions: The path through the wall or ceiling should be free from structural members, wiring, pipes, etc.

Intake Fan and Housing and Filter Housing: (items #581, #536 and 535) The intake fan is to be securely fastened to the intake damper housing or a rigid duct pipe that protrudes 1" from the surface of the wall, floor or ceiling. The intake fan housing then surrounds the intake fan and its gasketed open side is designed to be mounted on that surface. The filter housing may be mounted directly on the intake fan housing, as in the first two drawings. If the intake fan and filter are not to be located together, an optional insulated end panel (item #537) may be used here. The filter housing can then be mounted outside where better filter access may be possible, as shown in the third drawing.

  • Filter access is critical: A Freeairešs cooling capacity and effectiveness is directly related to the amount of air exchanged with the outside, which in turn depends on having a relatively clean filter. Therefore, it is very important to change the filter often, usually at least once a year. Whether or not a filter gets changed regularly depends a lot on where the filter housing is located, and how easy it is to get to it. If it is located in some dark, cramped, out-of-the-way crawl space where no one ever sees it, the filter may remain unchanged until the Freeaire brings in so little outside air that the compressor system is doing almost all the work. The energy savings will be severely reduced. Put the filter where it is seen and easily reached, preferably without a ladder.
  • Allow enough room: There should be at least 16" of unobstructed space to either side or on top of the of the filter housing to allow access for replacing the filter.

Intake Wallcap: (item #521) The intake wallcap is the point at which the outside air is pulled in from the outside. It may be mounted directly on an outside wall, as in the first drawing, on the filter housing, as in the second and third drawings. A flat roof requires a Flat Roof Vent Package (item #520), which has the same requirements as a wallcap:

  • Avoid sources of pollution: The wallcap or roof jack should be located as far away from sources of heat, dirt, or pollution as possible, especially auto and truck exhausts, furnace or woodstove chimneys, or dryer or gas appliance vents.
  • Avoid the sun: As the coldest air is usually found on the north side of a building (at least in the northern hemisphere), that side is the most preferable and the south side the least preferable.
  • Avoid a "short circuit": The intake wallcap should be at least 6 feet away from the exhaust wallcap to discourage warm exhaust air from just going right back into the cooler.

Connecting Duct: (Items # 518, #525, # 506-box or purchased locally)

  • Short, straight and smooth: Keep the duct as short, straight, and smooth as possible to maintain peak airflow and minimize heat gain when passing through a heated space. Rigid duct pipe inside a flexible insulated pipe is a good solution.
  • Insulate and seal: It should be tightly sealed and as well insulated as possible. Avoid passing through heated areas of the building.
  • Adequate support: The duct must be well supported along its entire length.
  • Watch the headroom: Be sure the duct does not restrict headroom if passing through a passageway. Protect it from damage if it is exposed or accessible.

The Exhaust Unit: The exhaust consists of three sections: 1) an exhaust fan housing, 2) a wallcap or optionalflat roof vent and 3) a connecting duct, if any.

Exhaust Fan Housing: (item #534) This is how the air leaves the walk-in cooler. It can be mounted in a wall, ceiling or floor, from inside the walk-in cooler. There is no filter and the fan is mounted inside the housing at the factory, so the exhaust fan housing is simpler to locate than the intake unit. The fan is located on the warm side of the insulated damper flaps in the summer, so condensation should not be an issue.

  • Exhaust the warmest air: Try to envision the flow of air from all the other fans inside the walk-in and locate the exhaust in an out of the way spot which will have the warmest air in the room. Avoid locating the exhaust directly in the airstreams coming from either the outside air fan, the circulating unit, or the evaporator fans. A good spot is often near the ceiling behind the evaporator fans and on the same wall as the intake unit, but at the opposite end of the walk-in.
  • Avoid obstructions. The path through the wall or ceiling should be free from structural members, wiring, pipes, etc.

Exhaust Wallcap: (items #521) The exhaust wallcap or flat roof vent, being the point at which the air from the walk-in cooler is returned to the outside, is much less difficult to locate than for the intake unit, since ongoing access to a filter is not necessary and sources of pollution are not a concern.

  • Avoid a "short circuit": The exhaust wallcap should be at least 6 feet away from the intake wallcap to discourage warm exhaust air from just going right back into the cooler.

Specifying Planning Installing Wiring Cooler Controller Commissioning & Troubleshooting Maintaining