CyberOne EC DX IOM Manual
valve is de-energized and hot gas flows directly from the
compressor discharge to the condenser. When there is a call
for reheat, the controller energizes the hot gas reheat solenoid
valve. The hot gas reheat solenoid valve diverts hot gas to the
reheat coil, mounted directly downstream of the evaporator
coil, before it travels to the condenser. No adjustment to the
valve is necessary.
2.9.7.1
Snap Acting Hot Gas Bypass (Optional)
3
The two most common systems provided by STULZ for hot
gas bypass are snap acting and full floating. The snap
acting hot gas bypass system provides some modulated
capacity control and freeze protection. The hot gas bypass
system includes a discharge bypass valve that allows some
hot gas from the compressor discharge line to pass into
the evaporator coil in order to maintain a preset suction
pressure.
The snap acting hot gas bypass system also provides freeze
protection for the evaporator coil by limiting the minimum
refrigerant pressure, thereby preventing the surface
temperature of the evaporator coil from dropping below
32 °F .
The normal control setting is 50
–
55 psig (suction pressure)
read from the suction (low) side of the compressor as it
operates in full hot gas bypass operation. The valve is factory
set and no adjustment should be necessary. If adjustment is
required, block one half of the coil and remove adjustment cap
from the end of the valve. Using a 5/16 inch Allen wrench,
turn clockwise to increase pressure or counterclockwise to
lower pressure.
3.2.1.1
Full Floating
A full floating hot gas bypass system is provided for split
AHU/Remote Condensing Units. The full floating hot gas
bypass system may include a quench valve and solenoid, a
quench thermal expansion valve, a hot gas (discharge) valve
and solenoid and a hot gas bypass valve.
The hot gas bypass valve allows refrigerant to flow from the
discharge line, directly to the suction line. The hot gas bypass
entering the suction side of the compressor would raise the
operating temperature of the compressor to a point where
failure could occur. To prevent overheating the compressor, a
small amount of liquid refrigerant passes through the quench
valve and mixes with the hot gas entering the compressor,
maintaining normal compressor suction pressure and
temperature.
The full floating hot gas bypass system provides freeze
protection for the evaporator coil by limiting the minimum
refrigerant pressure, preventing the surface temperature
of the evaporator coil from dropping below 32 °F. The hot
gas (discharge) regulating valve has a normal control setting
at 50
–
55 psig (suction pressure) read from the suction
(low) side of the compressor as it operates in full hot gas
bypass operation. The valve is factory set and no adjustment
should be necessary. If adjustment is required, remove
the adjustment cap from end of the valve. Using a 5/16
inch Allen wrench, turn clockwise to increase pressure or
counterclockwise to lower pressure.
CAUTION
Do not exceed 20 °F superheat. Exceeding this
temperature may cause failure of the compressor.
.
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