Cooling System Overview - Greenheck ERCH Installation, Operation And Maintenance Manual

Cooling System Overview

Water-Source Heat Pump with Three Way Hot Gas Reheat and Hot Gas Bypass
Water In
Waterside Coil
1. Compressor
2. High Limit Pressure Switch
The switch opens when refrigerant pressure
increases above the set point in the discharge line.
A manual reset is then required.
3. Hot Gas Reheat Valve (optional)
Units equipped with a reheat coil use a three-
way valve with actuator to control the supply
air discharge temperature of the unit during
dehumidification mode. The unit controller provides
a 0-10 VDC signal to control the amount of reheat
to meet the supply temperature set point.
4. Reversing Valve
Each compressor is equipped with a reversing
valve to reverse the direction of refrigerant flow.
Changing refrigerant flow allows the unit to switch
between heating and cooling mode.
5. Hot Gas Reheat Coil (Optional)
6. Hot Gas Reheat Check Valve (Optional)
7. Hot Gas Bypass Valve
On units equipped with hot gas bypass, hot gas
from the compressor is injected into the liquid line
of the evaporator coil after the TXV.
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 115 PSIG for R-410A (the valve will
feel warm to the touch). Adjustments are made by
first removing the cap on the bottom of the valve
and then turning the adjusting stem clockwise to
increase the setting pressure (counterclockwise
to decrease). Allow several minutes between
adjustments for the system to stabilize. When
adjustment is complete, replace the valve cap.
26 Energy Recovery Ventilator with Heating and Cooling General Description - NOT model specific
Water Out
9
HGB
HGC
Supply Airflow
10 11
LLF
TXV
6
HCV
SV
7
14
8
5 12
8. Hot Gas Bypass Check Valve
9. Coaxial Refrigerant-to-Water Heat Exchanger
The unit uses one coaxial heat exchanger per
compressor, essentially a tube inside a tube.
Water flows through the inner copper tube and
compressed refrigerant is forced through the
spaces between the inner and outer tubes.
Depending on whether the unit is functioning in
cooling or heating mode, heat is rejected from one
tube to the other.
10. Liquid Line Filter Drier
11. Thermostatic Expansion Valve (TXV)
Each unit is equipped with a TXV 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 access panel.
12. Airside Coil
Each unit uses a single refrigerant coil known as
an airside coil. If two compressors are used in the
unit, then the airside coil will be a split configuration
so that each compressor has a dedicated portion
of the airside coil. Depending on whether the
unit is in cooling or heating mode, the airside coil
will function as either a condensing coil or an
evaporator coil.
13. Low Limit Pressure Switch
The switch is installed on the suction line and
disables the DX system when the suction pressure
drops below the set point. The switch will auto
reset when the pressure rises above the auto-reset
set point.
14. Service Access Ports
M
HRV
4
4WV
HPS 2
SV 14
13
LPS
SV
14
1
3
®