Refrigeration Piping

NOTE: Always trap drain lines individually to prevent vapor migration.

Figure 5. Drain Line

Suction Lines

NOTE: If the suction line must rise to the point higher than the suction connection on the evaporator, a suction line trap at the outlet of the evaporator must be provided.

Horizontal suction lines should slope away from the evaporator toward the compressor at the rate of 1/4’ per 10 feet for good oil return. When multiple evaporators are connected in series using a common suction line, the branch suction lines must enter the top of the common suction line.

Suction lines that are outside of refrigerated space must be insulated. See “Line Insulation” for more information.

Suction Line Risers

NOTE: To provide proper oil return, a suction trap must be provided at the base of all suction risers.

Prefabricated wrought copper traps are available, or a trap can be made by using two street ells and one regular ell. The suction trap must be the same size as the suction line. For long vertical risers, additional traps may be necessary. Generally, one trap is recommended for each length of pipe (approximately 20 feet) to insure proper oil movement. See Figure 4 below for methods of constructing proper suction line P-traps.

Figure 4. Suction P-traps

Condensate Drain Lines

Copper drain lines should be used and properly protected from freezing. In running drain lines, provide a minimum of 4 inches per foot pitch for proper drainage. Drain lines should be at least as large as the evaporator drain connection. All plumbing connections should be made in accordance with local plumbing codes. All condensate drain lines must be trapped, and run to an open drain. They must never be connected directly to the sewer systems. Traps in the drain line must be located in a warm ambient. We recommend a trap on all evaporators. Traps located outside, or extensive outside runs of drain line must

be wrapped with a drain line heater. The heater should be connected so that it is continuously on. It is recommended that the drain line be insulated to prevent heat loss. A heat input of 20 watts per lineal foot of drain line for 0ºF (-18°C) room applications and 30 watts per lineal foot for -20°F (-29°C) rooms is satisfactory.

Inspect the drain pan periodically to insure free drainage of condensate. If the drain pan contains standing water, check for proper installation. The drain pan should be cleaned regularly with warm soapy water.

WARNING: All power must be disconnected before cleaning. The drain pan also serves as cover for hazardous moving parts. Operation of unit without drain pan constitutes a hazard.