Walk-In Cooler Condensate and Clearance
A 10 ft by 12 ft walk-in cooler is being installed in a restaurant back-of-house. The condensing unit is a 3 hp air-cooled unit placed in a mechanical alcove 30 inches from a wall on one side, 12 inches from a wall on the other, and 18 inches below a ceiling soffit. Manufacturer instructions require 36 inches of clearance on the service side, 24 inches on the air-intake side, and unobstructed discharge above the unit. The evaporator is mounted on the cooler's interior ceiling, and condensate drains through a 3/4-inch PVC line that runs 25 feet with a 1/8-inch-per-foot slope to a floor drain. The refrigerant is R-448A, and the line set passes through a 6-inch wall penetration that is sealed with expanding foam. The cooler is a prefabricated listed assembly.
1. Assess the condensing unit placement against the listed clearances and explain the consequences of the current layout.
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The unit fails the manufacturer's clearances on at least two sides. The service side has 30 inches where 36 inches is required, and the air-intake side has 12 inches where 24 inches is required. The 18-inch soffit above the unit may also obstruct discharge, depending on whether the unit discharges vertically and what the instructions require for unobstructed discharge above.
Consequences: restricted intake raises condensing temperature and discharge pressure, reducing capacity and efficiency and increasing compressor load; restricted discharge can recirculate hot air back to the coil, further raising head pressure. Reduced service clearance is a code and practical problem - the unit cannot be properly serviced or have components replaced, and the installation does not match the listing and manufacturer's instructions, which are part of the approved installation.
The layout must be revised: relocate the unit or rework the alcove so all listed clearances are met, or select a unit whose listing permits the available clearances.
2. Evaluate the condensate drain and the refrigerant line penetration for compliance and durability.
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Condensate drain: a 3/4-inch line at 1/8 inch per foot over 25 feet gives about 3.1 inches of total fall, which is adequate slope, but the drain must be trapped and protected against freeze-up if any portion is exposed, and it must discharge to an approved receptor. A long run to a floor drain is acceptable if the slope is maintained and the line is supported. Verify the drain does not pass through the cooler's insulated envelope without a proper sleeve and seal, and that the evaporator pan drains fully.
Refrigerant line penetration: sealing a line set through a wall with expanding foam is questionable. The penetration must be sealed to maintain the envelope, but the sealant must be compatible with the line insulation and must not create a hard, rigid restraint that stresses the tubing; the lines also need to be isolated from vibration and supported. The penetration should be sleeved and sealed with a suitable sealant, and the line set should be protected where it passes through the wall. R-448A is an A1 refrigerant, but brazing and leak testing still require the appropriate procedures and documentation.