Greenheck Coils - Manual (Page 6)

Page 6 of 7 IOM, Rev. 2, November 2007
Copyright © Greenheck Fan Corporation
CAUTION: Disassemble the thermal expansion valve before completing the brazing connections. If
necessary, wrap the valve in a cool wet cloth while brazing. Failure to protect the valve from high
temperatures may result in damage to the internal components.
C. Suction Line Sizing
Suction line tubes must be sized to maintain refrigerant vapor velocities that are high enough to ensure
good oil return to the compressor under all operating conditions. It is necessary to pitch horizontal
suction lines toward the compressor to insure sufficient oil return to the compressor. Traps should be
provided at the bottom of suction line risers and at 15 foot intervals for sufficient oil return.
D. Suction Line Components
A suction line pressure tap should be installed on the leaving side of the evaporator coil near the TEV
sensing bulb location. Accurate superheat measurement and TEV adjustment demands that suction
pressure and temperature be measured near the evaporator coil outlet.
Suction line filter-driers are usually only necessary on systems that have experienced a severe
compressor motor burn out or other failure that results in extremely high refrigerant temperature. This
filter-drier should not be left in the suction line permanently.
Suction lines should be insulated completely with sufficient wall thickness insulation for the application
temperature range being utilized.
Installation Checklist
Use the following checklist to verify that all necessary installation procedures have been completed.
1. Coils are installed with airflow in same direction as indicated on the coil nameplate or casing.
2. Suction connection is at the bottom of the suction header on the evaporator coil, suction line is
pitched towards compressor and traps are installed in suction risers. Suction line is insulated with
correct wall thickness insulation for the temperature application utilized.
3. If stacking coils, stacking channels are properly installed and bypass air is prevented.
4. Condensate drain pans and piping is installed with a trap in the condensate line and piping insulated
and heated if installed in applications that are below freezing.
5. Clean filters are installed upstream of the condenser coil when applicable.
6. A liquid line filter-drier is installed upstream of the expansion valve.
7. A moisture indicator/sight glass is installed between the expansion valve and filter-drier.
8. A liquid line shutoff valve with access port is installed close to the condenser.
9. A schrader valve is installed in the suction line close to the evaporator coil outlet.
10. The TEV, with external equalizer connections, is installed directly on the evaporator liquid connection,
sensing bulb mounted in the horizontal position on the suction line and insulated. The liquid distributor
must be in a vertical position.
11. Piping system is leak-tested with dry nitrogen, evacuated to 500 microns, and charged with correct
refrigerant type and amount.
12. Superheat and sub cooling measurements are taken. Thermal expansion valve is adjusted to obtain
desired superheat. Desired superheat on most applications is 8° to 12° at the outlet of the evaporator.