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CAUTION! UNIT IS PRESSURIZED
WITH DRY AIR OR INERT GAS
FOR SHIPPING
THIS HOLDING CHARGE MUST
BE VENTED AND THE SYSTEM
LEAK TESTED AND EVACUATED
BEFORE CHARGING WITH RE-
FRIGERANT
CHARGE SYSTEM WITH ONLY
PURE, VIRGIN REFRIGERANT
Refer to ASHRAE REFRIGERATION HANDBOOK for detailed system piping design information!
Always consider the overall length of field piping runs when locating unit coolers and matching condensing units. Excessivel y
long piping runs should be avoided whenever possible.
Select the optimum pipe size which minimizes total system pressure drop while maintaining sufficient internal gas velocities to
ensure continuous oil return back to the compressor. Often times pipe selection is a compromise between operating efficiency
over the lifetime of the system and initial, installed cost.
Pitch all horizontal suction lines in the direction of refrigerant flow (minimum 1/4" / foot of run) to ensure oil return. Install a P-
trap at the bottom of ALL vertical suction risers (Figure 1). This not only helps with oil return but protects the expansion valve
sensing bulb from the affects of liquid drain back at the outlet of the evaporator.
Install an intermediate P-trap in all vertical risers over 20' and every 15' thereafter.
A P-trap is not required at the outlet connection if the field piping travels horizontally leaving the unit and is pitched sharply
away from the unit (Figure 2). Likewise a trap is not needed if the piping turns down immediately exiting the unit.
Reduce suction riser size when necessary to help maintain minimum gas velocity and ensure continuous system oil return.
Install inverted P-traps at the top of individual suction risers when piping multiple suction risers from individual units into a com-
mon suction line located above the evaporator outlets.
Provide adequate pipe supports near the unit cooler connections and at regular intervals to help maintain pitch (prevent line
sagging) and excessive movement / breakage. Support all external valves and piping components individually.
Install auxiliary suction to liquid heat exchangers whenever necessary to overcome excessive liquid line heat gain and / or pres-
sure drop due to exposure to high ambient temperatures or tall vertical risers. When properly selected and applied such devic-
es will help maintain 100% bubble free liquid at the TXV inlet.
Insulate all field piping (both suction and liquid lines) where practical to avoid excessive heat gain and condensation drippage
which may pose a potential safety hazard to personnel and the immediate environment. Protect insulation from physical dam-
age and destructive UV rays with industry approved jacketing materials or coating.
Although the suction line is the most critical from an overall system capacity and oil return standpoint the liquid line must also
be properly sized to minimize pressure drop and ensure 100% vapor free liquid is continuously delivered to the inlet of the TXV.
Condensing Unit
Air Flow
REFRIGERANT PIPING
Use only clean, sealed ACR grade copper tubing for refrigerant duty. Unit warranty cover-
age may be voided if system is installed with any other type of tubing. All piping must be
installed according to local and national codes as well as accepted commercial refrigeration
industry standards and practices. All tubing should be cut using a wheel type tubing cutter
(no hacksaws) and all cut tubing must be de-burred. Clean all joints with sand cloth and
apply a small amount of high quality paste flux (being careful to avoid placing any flux near
the ends of the tubing) before firmly joining connections. When brazing, use only high tem-
perature, silver bearing solder on all joints while continuously flowing a regulated, low pres-
sure, inert gas through the inside of the piping to avoid the formation of scale and copper
oxides.
Note: The line sizing required for the system is not necessarily the same size as the factory
pipe connections supplied on the unit. We strongly recommend that you work directly with
an experienced consulting engineer to properly size and design system piping however as a
convenience to our customers (and with no liability for services provided as gratis) we can
supply the installer with line sizing charts which may be used to select the field line sizing
based upon the calculated, overall equivalent feet of tubing (lineal feet plus allowances for
fittings), refrigerant type, unit capacity and SST.
GENERAL UNIT PIPING GUIDELINES
Pitch To Flow
Unit Cooler
P-Trap
Figure 1
Air Flow
Vertical
Suction
Riser
10
Unit Cooler
Suction
Line
Figure 2
Condensing Unit
Pitch
To
Flow
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