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•
If the DX LAT drops to 35°F or less for 10 minutes, the
OEM controller will issue an alarm and the compressor
stops. When the DX LAT warms back up to 55°F or more,
the compressor turns back on.
•
Hot Gas Reheat (HGRH) — On/Off:
- When the SAT is 1°F (adjustable) or more below the
SAT cooling set point, HGRH turns on and cycles to
maintain the SAT cooling set point.
- When SAT is 2°F (adjustable) or more above the SAT
cooling set point, HGRH turns off.
•
Switchable Sub-Cooling:
- When either of the compressors are enabled during
dehumidification mode, the subcooling coil is enabled.
When the compressors are disabled, the subcooling coil
is disabled.
DEHUMIDIFICATION MODE (FIELD ENABLED)
•
Dehumidification Mode is available if the ECAT is 1°F
(fixed) above the dehumidification lower limit of 60°F
(adjustable) and there is no call for heating.
•
When the Entering Coil Air Dew Point (ECDP) is 1°F (ad-
justable) or more above the Supply Air Dew Point (SADP)
set point (55°F, adjustable), Dehumidification Mode is en-
abled. After the minimum time-off delay, compressor #1
turns on.
•
When the ECDP is 2°F (adjustable) or more below the
SADP set point, compressor #1 turns off and Dehumidifi-
cation Mode is disabled.
•
HGRH is enabled to operate as necessary to maintain the
SAT cooling set point (72°F, adjustable).
•
When the SADP is 1°F (adjustable) or more below SADP
set point, compressor #2 turns off.
•
When ECDP is 2°F (adjustable) or more below the SADP
set point, compressor #1 turns off and Dehumidification
Mode is disabled.
•
Hot Gas Reheat (HGRH) — Modulating:
- When the SAT is 1°F (adjustable) or more below the
SAT cooling set point, HGRH turns on and modulates to
maintain the SAT cooling set point.
- When SAT is 2°F (adjustable) or more above the SAT
cooling set point, HGRH turns off.
•
Switchable Sub-Cooling:
- When either of the compressors are enabled and the
SAT is equal to or below the SAT cooling set point
(72°F, adjustable), the subcooling coil is enabled.
- When the SAT is 1°F (adjustable) or more above the
SAT cooling set point (72°F, adjustable), the sub-
cooling coil is disabled.
HEATING MODE
•
Heating Mode is available when the ECAT is below the
ECAT heating upper limit (60°F, adjustable) and there is a
demand for heating.
•
When the ECAT is 1°F (adjustable) or more below the
ECAT heating set point (55°F, adjustable), heating is en-
abled and operates to maintain SAT heating set point
(70°F, adjustable).
•
When ECAT is 1°F (adjustable) or more above ECAT
heating set point (55°F, adjustable), heating is disabled.
•
Staged Heat (Electric Heat):
- 2-Stage Heat: Terminal W1 turning on enables first-stage
heating. As SAT goes further below the SAT heating set
point (70°F, adjustable), terminal W2 energizes and sec-
ond-stage heating is enabled. As SAT rises, terminal W2
turns off and second-stage heating turns off. As the SAT
goes 1°F (adjustable) or more above the SAT heating set
point (70°F, adjustable), terminal W1 turns off and first-
stage heating turns off.
- 4-Stage Heat: Terminal W1 turning on enables the Heat-
ing Analog Relay Module (HARM) on the control panel
which activates the different stages of heating. As the
SAT goes further below the SAT heating set point (70°F,
adjustable), the different stages will turn on. As the SAT
goes further above the SAT heating set point (70°F,
adjustable), the different stages will turn off.
•
Gas Furnace: Terminal W1 turning on energizes the gas
furnace controller and first-stage auxiliary heating is en-
abled. If the SAT is 1°F (adjustable) or more above the
SAT heating set point (70°F, adjustable), terminal W1
turns off which de-energizes the gas furnace controller,
and first-stage auxiliary heating is turned off. All other
stages operate as above.
•
Modulated Heat:
- SCR Electric Heat: On demand for heating, the OEM
controller modulates the electric heating SCR in order
to maintain the SAT heating set point (70°F, adjustable).
- Modulating Gas Furnace: On demand for heating, the
OEM controller modulates the gas furnace controller to
control the gas flow in order to maintain the SAT heat-
ing set point (70°F, adjustable).
- Modulating Hot Water Heat: On demand for heating,
the OEM controller modulates the hot water valve to
control the hot water flow in order to maintain the SAT
heating set point (70°F, adjustable).
- Modulating Steam Heat: On demand for heating, the
OEM controller modulates the steam valve to control
the flow of steam in order to maintain the SAT heating
set point (70°F, adjustable).
UNOCCUPIED MODE
•
When the Occupancy Control indicates the end of the Oc-
cupied Mode, the compressor(s) and outdoor fan(s) will
turn off (subject to minimum run-time) or the heating sys-
tem will turn off. The SF and EF will continue to run for 2
minutes before turning off.
•
After this, the ECW will turn off and the OA damper will
close. The unit is now off.
SAFETY SWITCHES
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High Pressure Switch (HPS1): If HPS1 is open, compres-
sor #1 will turn off and the OEM controller will issue an
alarm. After manually resetting HPS1, the HPS1 alarm
will reset. Following a minimum time off delay, compres-
sor #1 will turn on. If the OEM controller records 3 high
pressure start/restart failure incidents within 1 hour, com-
pressor #1 is locked out and the OEM controller will issue
an alarm. The compressor lock-out can be reset in the
Equipment Touch display pad or by cycling the power of
the OEM controller.
- This sequence is the same for compressor #2, Y2, and
HPS2.
•
Low Pressure Switch (LPS1): If LPS1 is open after the
LPS1 bypass time, the OEM controller will issue an alarm
and compressor #1 turns off. After 30 seconds (fixed), the
LPS1 alarm will reset. Following a minimum time off de-
lay, compressor #1 will turn on. If the OEM controller re-
cords 3 low pressure start/restart failure incidents within 1
hour, compressor #1 is locked out and the OEM controller
will issue an alarm. The compressor lock-out can be reset
in the Equipment Touch display pad or by cycling the
power of the OEM controller.
- This sequence is the same for compressor #2, Y2, and
LPS2.
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