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PIPE SIZING GUIDELINES
Piping design and line sizing is the responsibility of the installer. The following table can be used as
a guideline. The ‘Net Distance to Condensing Unit’ column allows 50% of the Distance for the
equivalent restriction to refrigerant flow caused by elbows. We recommend the installer minimize
restriction to refrigerant flow by incorporating the following features in their design: Use fewer elbows;
use long radius elbows when possible; use 45° elbows instead of 90° elbows, if possible. A vertical
suction riser greater than 3 to 4 feet in height should have a P trap at the base to facilitate oil return
up the riser. For long vertical risers, an additional P trap is recommended for each 20 feet of riser to
assure proper oil movement.
Additional information is available from your compressor manufacturer's system design manual.
OUTDOOR CONDENSING UNITS
Outdoor condensing units are equipped with weather resistant outdoor covers, crankcase heaters and
head pressure valves to control the flow of refrigerant through the condenser.
Refrigerant charging of the system in ambients above 70°F requires additional charging equal to the
pounds necessary to flood the condenser under low ambient conditions, as defined in the chart below:
MODEL CONDENSING UNIT APPROXIMATE ADDITIONAL
(HP) R-404A CHARGE
HQC135 3 or 3
1
/4 8 lbs
HQC200 5 15 lbs
Charging of the system with refrigerant in ambients below 70°F requires caution to prevent overcharging
since the pressure control valve will already be partially functioning and the amount of additional
charge must be determined.
VALVE AND PRESSURE SETTINGS
LOW PRESSURE CONTROL SETTING
(Refrigerant R-404A)
Low Pressure Cut-In 30 psig
Low Pressure Cut-Out 10 psig
The ideal superheat at the evaporator outlet is 8 – 10°F.
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