21
M
INI
-S
PACE
EC I
NSTALLATION
, O
PERATION
AND
M
AINTENANCE
M
ANUAL
2.10.6 Hot Gas Reheat (Optional)
The hot gas reheat option incorporates a hot gas reheat
solenoid valve and a hot gas reheat coil. Under normal
operation when no reheat is required, the hot gas reheat
valve is de-energized and hot gas fl ows 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.
2.10.7 Snap Acting Hot Gas Bypass (Optional)
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 120 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 3/8 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.
2.11 Refrigerant
Characteristics
2.11.1 Pressure/Temperature Settings
Table 6 is provided to assist with the normal settings of the
system for R410A refrigerant. Where applicable, minimum
and maximum settings are given along with normal operating
pressures.
2.11.2 Saturated Refrigerant Pressure
The refrigerant temperature/pressure table (Table 7) is
provided for reference for R410A refrigerant.
R410A Refrigerant Pressure/Temperature Settings
Normal Min. Max.
Sub-cooling °F
10 5 20
Superheat
°F
15 10 20
Design Condensing Temp. @ 95°F Ambient
125
105
140
Suction Pressure (psig)-
130
105
155
Fan Cycling Control- Fan On (psig)-
440
330
480
Fan Speed Control (psig)-
440
-
-
Table 6.
R410A Pressure/Temperature Settings
Temp.
Pressure
(°F)
(psig)
20
78.4
22 81.9
24 85.5
26 89.2
28 93.1
30 97.0
32 101
34 105
36 109
38 114
40 118
42 123
44 128
46 133
48 137
50 143
55 155
60 170
65 185
70 201
Temp.
Pressure
(°F)
(psig)
75 218
80 236
85 255
90 274
95 295
100 318
105 341
110 365
115 391
120 418
125 446
130 477
135 508
140 541
Table 7.
R410A Refrigerant Pressure
