Product data

Long Line Applications - 38HDL (continued)
7. Changes in piston size. The metering device for long line applications must be adjusted to compensate for the
frictional losses due to the long refrigerant lines, refrigerant line accessories, and indoor coils above or below
the outdoor unit. The AccuRater refrigerant metering device piston may need to be changed to provide this
adjustment. The AccuRater piston should be changed at the indoor unit depending upon system configuration
and line length. Use the Change in Indoor/Outdoor Piston Size for Elevation table #4 to determine the correct
piston size. The standard system’s piston size is shown in the Piston/Charge Combination Section.
a. Horizontal configuration: For horizontal applications no piston change is required. For additional charge
see step #10.
b. Elevated Configuration: Using table #4, add or subtract the change from the original piston size number. If
the piston size is decreased, round down to the next common piston size. If the piston size is increased,
round the new pistons size up to the next common size. See table #5
8. Liquid line solenoid and tubing configuration: The solenoid has a flow arrow stamped on the valve body. When
the valve is closed (not energized) and pressure is applied in the direction of the flow arrow, complete shut off
will occur. If pressure is applied against the direction of the arrow, leakage through the valve will occur. When
determining the proper location for a solenoid in a system liquid line, consider both flow direction and location
of the valve in the system. See Diagram #1thru #4 for proper location and install as follows:
a. Horizontal configuration Diagram #1
1. Install a liquid line solenoid valve within 2 feet of the fan coil with the flow arrow pointing
toward the indoor unit if equivalent feet of piping is 50 feet or more.
2. Slope the vapor line toward the indoor unit to provide for refrigerant migration protection during the
off cycle due to temperature differences caused by slight elevation changes between indoor and
outdoor units.
NOTE: When installing a liquid line solenoid, a low voltage transformer may be required.
b. Elevated configuration: (Lift) Indoor unit above outdoor unit Diagram #3
1. No Solenoid is required below 25 feet of lift. If there is over 25 feet of lift, a solenoid valve is required
in the liquid line within 2 feet of the condenser with the flow arrow pointing toward the outdoor unit.
2. The maximum elevation difference is 65 feet and the maximum equivalent length of piping is 100 feet.
3. Install an inverted trap in the vapor line. The top of the trap must be above the top of the indoor unit.
This prevents the refrigeration from collecting in the vapor line.
c. Lowered configuration: (Drop) Indoor unit below outdoor unit Diagram #4
1. For lines shorter than 100 feet, no solenoid valve is required in the liquid line.
2. The maximum elevation difference is 75 feet and the maximum equivalent length of piping is 100 feet.
9. Additional Charge: The unit should be charged by weighing in the appropriate amount of refrigerant. Add
charge based on the additional length of line which is over 25 feet. Add 0.58 oz of refrigerant for every 1 foot
increase over the 25 feet. See Piston/Charge Combination Section for standard charge at 25 feet of liquid line
length.
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