Specifications

2.0 PIPING

2.1 Air Cooled Unit Piping

Refer to the attached line sizing chart on page 32 for a guideline for sizing refrigerant lines. The

ultimate responsibility for line size selection is that of the installing contractor or project engineer.

Data Aire does not assume this responsibility. The chart covers distances up to 200 equivalent feet.

For installations beyond this distance, consult ASHRAE or similar references.

Standard piping practice must be used to ensure proper oil return and efﬁ cient operation.

The interconnecting lines to the remote air cooled condenser must be installed by a qualiﬁ ed

refrigeration mechanic.

2.1.1 Discharge lines

Discharge lines, also called hot gas lines, should be trapped at the top (inverted) and bottom

as well as every 15 to 20 feet of vertical rise. Discharge line check valves are recommended on all

installations, especially those where there are long pipe runs or cold climates. Check valves should

be installed no less than six to ten feet from the compressor. The discharge, suction and liquid lines

need to be refrigerant grade copper and in accordance with local code. All refrigeration piping should

be installed with high temperature brazed joints. When brazing, a supply of nitrogen gas needs to

be fed through the refrigerant lines. Be sure to open the other end of the refrigerant line to allow the

nitrogen to bleed off and not pressurize the piping. Prevailing good refrigeration practices should be

employed for piping support, leak testing, dehydration and charging the refrigerant circuits. During

the installation the lines should be capped off and ﬁ lled with dry nitrogen at the end of each day’s

work or until the system is completed and sealed.

Data Aire recommends a silver/phosphorus/copper alloy with 5 to 15% silver be used to braze

the refrigerant line sets to the indoor and outdoor units. Nitrogen needs to be ﬂ owing through the

lines to eliminate carbon deposit buildup on the inside of the joints. Carbon could contaminate the

refrigerant and restrict the metering device.

Piping must be supported within 18” of the inlet and outlet connections. The inlet connection is

located on the top header of all units. The discharge outlet is located at the bottom of the header.

Discharge line pressure should not exceed 6 PSI for R-407C and 9 PSI for R-410A. Recommended

gas velocity for proper oil return is 1,000 FPM. Slope horizontal lines downward in the direction of

refrigerant ﬂ ow (1/2” for every ten feet of line length). Discharge lines do not require insulation but

due to the high temperatures of the refrigerant inside the line, the pipes may be insulated to protect

against burns to individuals near or around the lines.

2.1.2 Liquid lines

Liquid line size is determined by pressure drop and velocity. The liquid line pressure drop for

R-407C should not exceed 5 PSI or 9 PSI for R-410A. The recommended velocity should be between

200 and 300 FPM. To avoid excessive liquid line pressure drop, the air cooled condenser should

be located above or at the same level as the evaporator. Condenser installation more than ten feet

below the evaporator is not recommended. Insulation of liquid lines is not required but can be useful

in preventing condensation from forming and to avoid ﬂ ashing on long pipe runs.