Greenheck ERCH - Energy Recovery Unit with Packaged DX (468151) - Manual (Page 32)

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Energy Recovery Unit with Packaged DX
Condensing Coil - each unit contains a condensing coil mounted on the exterior of the unit . High
temperature, high pressure gas from the compressor enters the coil and is eventually cooled into a high
temperature, high pressure liquid . The condensing fans move air over the coil which pulls the heat out of
the refrigerant . To ensure proper operation, the coil must be cleaned so that air movement over the coil
provides the necessary heat transfer .
Condenser Fans - depending on capacity, the unit is equipped with either 2 or 3 direct-drive
condensing fans . The fans provide the necessary airflow to cool the refrigerant in the condensing coil .
Depending on head pressure, one fan may not be running, which is normal operation for this unit and
does not highlight a problem . The motors are equipped with sling protection to guard against water
penetration, and are thermally protected . The thermal overloads shut down the condensing fans .
High Limit Pressure Switch - to safely shutdown the DX system, in case of an increase in refrigerant
pressure, a high limit pressure switch is included (located in compressor compartment) . The switch is
located in the compressor compartment . It trips when refrigerant pressure increase to 410 psi for the
R22 (600 psi for R410a) in the liquid line, and can only be manually reset when the pressure drops below
290 psi . Typically if the high limit switch trips, a failure in the system has occurred and more investigation
is needed to determine the underlying problem .
Head Pressure Cycle Switch - to maintain proper refrigerant pressures, a Fan-Cycle switch that
operates on head pressure is installed in the liquid line . When liquid line refrigerant pressure increases to
275 psi for R22 (425 psi for R410a), the switch closes and turns on an additional condensing fan to aid in
cooling the refrigerant . After turning on, the fan will run until liquid line pressure drops down to 210 psi
for R22 (330 psi for R410a) where it cycles off . The switch is located in the compressor compartment .
Liquid Line Filter Drier - the liquid line filter drier prevents moisture and foreign matter from entering
the thermal expansion valve . It is mounted in the compressor compartment .
Moisture Indicating Sight Glass - moisture in a DX system can cause great harm and break down the
refrigerant . Located in the compressor compartment is a 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 means moisture is below a
safe operation level in the refrigerant, while a yellow dot indicates moisture has been introduced into the
system and needs to be addressed .
Hot Gas Bypass Valve - on units equipped with hot bypass, hot gas from the compressor is injected
into the liquid line of the evaporator coil after the TXV . This process starts to occur when suction gas
temperatures drop below 28ºF, which is 32º–34ºF coil surface temperature . Hot gas helps prevent the
evaporator coil from freezing up and the compressor from cycling . The valve is factory set, but can be
adjusted to exact specifications once installed in the field .
Valve Adjustment - to adjust the valve, connect a pressure gauge to the suction line and
block the entering air to the evaporator coil . The Valve should begin to open when the suction
pressure drops to approximately 58 PSIG for R22 and 115 PSIG for R410a (the valve will feel
warm to the touch) . Adjustments are made by first removing the cap on the valve and then
turning the adjusting stem clockwise to increase the setting pressure and counterclockwise
to decrease the setting pressure . Allow several minutes between adjustments for system to
stabilize . When adjustment is complete, replace the cap on the valve .
Access Ports - For easy measurement and charging access, several ports are provided throughout the
system . These can be used to measure system pressures, and also charge or evacuate the system . Most
ports are located in the compressor compartment for easy access .
REFRIGERATION SYSTEM
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Factory Installed Refrigeration System Components