29
Heating Mode — Heating mode is available when the OAT is
below the OAT heating upper limit (60°F, adjustable) and there
is a demand to temper outdoor air to room neutral conditions.
When the ECAT is 1°F (adjustable) or more below the ECAT
heating set point (50°F, adjustable), heating is enabled and op-
erates to maintain SAT heating set point (70°F, adjustable).
When ECAT is 1°F (adjustable) or more above ECAT heating
set point (50°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 second-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.
STAGED HEAT (ELECTRIC HEAT) 4-STAGE
HEAT — Terminal W1 turning on enables the Heating Ana-
log Relay Module (HARM) on the control panel which acti-
vates the different stages of heating. As the SAT goes further
below the SAT heating set point (70°F, adjustable), the differ-
ent stages will turn on. As the SAT goes further above the SAT
heating set point (70°F, adjustable), the different stages will
turn off.
STAGED HEAT (GAS HEATER) 2-STAGE — 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 second-stage heating is enabled. As SAT ris-
es, terminal W2 turns off and second-stage heating turns off.
As the SAT goes 1°F (adjustable) or more above the SAT heat-
ing set point (70°F, adjustable), terminal W1 turns off and first-
stage auxiliary heating turns off.
STAGED HEAT (GAS HEATER) 4-STAGE — Terminal
W1 turning on enables the Heating Analog Relay Module
(HARM) on the control panel which activates the different
stages of heating. As the SAT goes further below the SAT heat-
ing 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 Heater: Terminal W1 turning on energizes the gas heat
controller and first-stage axillary heating is enabled. If the SAT
is 1°F (adjustable) or more above the SAT heating set point
(70°F, adjustable) terminal W1 turns off, which deenergizes
the gas heat controller, and first-state axillary heating is
turned off. All other stages operate as above.
MODULATED HEAT — SCR Electric Heat: On demand to
temper outdoor air to room neutral conditions, the controller
modulates the electric heating SCR in order to maintain the
SAT heating set point (70°F, adjustable).
Modulating Gas Heater: On demand to temper outdoor air to
room neutral conditions, the controller modulates the gas heat
controller to control the gas flow in order to maintain the SAT
heating set point (70°F, adjustable).
Modulating Hot Water Heat: On demand to temper outdoor air
to room neutral conditions, the controller modulates the hot
water valve to control the hot water flow in order to maintain
the SAT heating set point (70°F, adjustable).
UNOCCUPIED MODE — When the Occupancy Control
in-
dicates the end of the Occupied mode, the compressor(s) and
outdoor fan(s) will turn off (subject to minimum run-time) or
the heating system 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
•
High Pressure Switch (HPS1):
If HPS1 is open, com-
pressor no. 1 will turn off and the controller will issue an
alarm. After manually resetting HPS1, the HPS1 alarm
will reset. Following a minimum time off delay, com-
pressor no. 1 will turn on. If the controller records 3 high
pressure start/restart failure incidents within 1 hour,
compressor no. 1 is locked out and the controller will
issue an alarm. The compressor lockout can be reset in
the Equipment Touch display pad or by cycling the
power of the controller. This sequence is the same for
compressor no. 2, Y2, and HPS2.
•
Low Pressure Switch (LPS1):
If LPS1 is open after the
LPS1 bypass time, the controller will issue an alarm and
compressor no. 1 turns off. After 30 seconds (fixed), the
LPS1 alarm will reset. Following a minimum time off
delay, compressor no. 1 will turn on. If the controller
records 3 low pressure start/restart failure incidents
within 1 hour, compressor no. 1 is locked out and the
controller will issue an alarm. The compressor lockout
can be reset in the Equipment Touch display pad or by
cycling the power of the controller. This sequence is the
same for compressor no. 2, Y2, and LPS2.
SAFETY SHUTDOWN —
Smoke Detector:
When a smoke
detector (SD) is provided, it is wired directly to the controller.
If smoke is detected, the controller will shut down the unit.
Other instances where shutdown will occur are as follows. If a
compressor fails to start 3 times in an hour due to high pressure
switch lock out; If a compressor fails to start 3 times in an hour
due to low pressure switch lock out; If a compressor fails to
start 3 times in an hour due to DX leaving air temperature lock
out; and if the controller detects an SAT sensor failure.
REFRIGERANT CHARGING — The 62X series units come
from the factory with the appropriate operating charge of
R-410A.
Charge adjustment might be necessary if subcooling tem-
peratures are too high due to excess refrigerant in the system
that is subsequently backed up in the condenser. This symptom
could also indicate a failed TXV or line restriction. If there is
no line restriction and the TXV is working correctly, reclaim
enough R-410A refrigerant so the system ambient compensat-
ed pressure readings are at the desired levels. Use a refrigerant
recovery unit to safely remove the refrigerant, because it is ille-
gal to release R-410A refrigerant into the atmosphere. After the
addition or removal of refrigerant, the unit must be allowed to
stabilize for at least 10 minutes before reaching any conclu-
sions if any other adjustments need to be made.
All 62X series units are equipped with hot gas reheat or liq-
uid subcooling reheat. Operation of the reheat system must be
disabled prior to charging unit. To disable, use the unit control
interface to disable reheat operation, or disconnect the power or
control signal to the reheat valve or solenoid assembly.
The type of unit and operation determines the ranges for liq-
uid subcooling and evaporator superheat. The system is over-
charged if the subcooling temperature is too high and the evap-
orator is fully loaded. High superheat results in increased sub-
cooling. The system is defined as undercharged if the superheat
is too high and the subcooling is too low.
To correct an undercharged system, add refrigerant to re-
duce the superheat and raise subcooling. If the subcooling is
correct and the superheat is too high, the TXV may need ad-
justment to correct the superheat. When checking the charge,
units with hot gas reheat must be checked with the hot gas re-
heat valves closed and the system in cooling mode. To confirm
proper charge, the unit should be left in reheat mode to check
for proper operation. See Table 10 for proper charge levels.
