Greenheck Packaged DX Module (474681) - Manual (Page 6)

6 Packaged DX Module for Make-Up Air Unit
Factory Installed Refrigeration System Components
Evaporator Coil
Condenser Coil
1
2
3
4
11
5
10
13
9
8
12
7
6
Service Valve for Subcooling Gauge/
High Side Pressure Drop
Circuit A
Service Valve for
Superheat and Low
Side Pressure
Pressure Port for
Troubleshooting
Reheat Valves
High Side
Pressure Drop
4. Low Limit Pressure Switch
The switch is installed in the suction line and
disables the DX system with the suction pressure
drops below the set point. The switch will auto-reset
when the pressure rises above the auto-reset set
point.
5. Compressors
6. Condensing Coil
7. Condenser Fans
8. High Limit Pressure Switch
The switch opens when refrigerant pressure
increases above the set point in the liquid line and it
then requires a manual reset.
9. Liquid Line Filter-Drier
The liquid line filter-drier prevents moisture and
foreign matter from entering the expansion valve.
10. Moisture Indicating Sight Glass
During normal operating conditions, the sight glass
should typically be liquid. Some gas is acceptable,
but excessive bubbles may indicate improper
charge or a leak in the system. A green dot indicates
the moisture level in the refrigerant, while a yellow
dot indicates moisture in the system and needs to
be dealt with.
11-13. Access Ports
1. Thermostatic Expansion Valve (TXV)
Each unit is equipped with a Thermal Expansion
Valve on each refrigerant circuit. The valve
controls the flow of liquid refrigerant entering the
evaporator coil by maintaining a constant, factory
set superheat of 10°F. The valve is adjustable and is
located on the side of the evaporator coil and can
be accessed through the coil panel access door.
2. Refrigerant Distributor
Attached to the TXV is a refrigerant distributor.
The refrigerant distributor evenly distributes the
refrigerant to each circuit of the evaporator coil to
provide optimum performance.
3. Evaporator Coil
The coil is located in the supply airstream. In the
DX system, the liquid refrigerant is expanded in
the TXV and it then flows through the evaporator
coil. The refrigerant enters the coil as a low
temperature liquid/gas where it eventually boils into
a low temperature, low pressure gas prior to going
into the compressor. As the refrigerant passes
through the evaporator coil, it absorbs heat from
the airstream. To ensure proper operation, the coil
surface must be cleaned so that air movement over
the coil provides the necessary heat transfer.
®