Controls - Carrier 50TFF007-014 Product Data

Controls

Operating sequence
Cooling, units without economizer — When thermo-
stat calls for cooling, terminals G and Y1 are energized.
The indoor (evaporator) fan contactor (IFC), and compres-
sor contactor no. 1 (C1) are energized and evaporator-fan
motor, compressor no. 1 and condenser fans start. The
liquid line solenoid valve for compressor no. 1 is deener-
gized to open. The condenser-fan motor runs continuously
while unit is cooling. On 50TFF008-014 units, if the ther-
mostat calls for a second stage of cooling by energizing Y2,
compressor contactor no. 2 (C2) is energized and com-
pressor no. 2 starts.
Heating, units without economizer (If Accessory
Heater is Installed) — Upon a call for heating through
terminal W1, IFC and heater contactor no. 1 (HC1) are
energized. On units equipped for 2 stages of heat, when
additional heat is needed, HC2 is energized through W2.
Cooling, units with Durablade economizer — When
the outdoor-air temperature is above the outdoor-air ther-
mostat (OAT) setting and the room thermostat calls for
cooling, compressor contactor no. 1 is energized to start
compressor no. 1 and the condenser-fan motor. The
evaporator-fan motor is energized and the economizer
damper moves to the minimum position. Upon a further
call for cooling, compressor contactor no. 2 will be ener-
gized (50TFF008-014), starting compressor no. 2. After
the thermostat is satisfied, the damper moves to the fully
closed position.
When the outdoor-air temperature is below the OAT set-
ting and the thermostat calls for cooling, the economizer
dampers move to the minimum position. If the supply-air
temperature is above 13.9 C (57 F), the damper continues
to open until it reaches the fully open position or until the
supply-air temperature drops below 13.9 C (57 F).
When the supply-air temperature falls to between
13.9 C (57 F) and 11.1 C (52 F), the damper will remain at
an intermediate open position. If the supply-air tempera-
ture falls below 11.1 C (52 F), the damper will modulate
closed until it reaches the minimum position or until the
supply-air temperature is above 11.1 C (52 F). When the
thermostat is satisfied, the damper will move to the fully
closed position.
If the outdoor air alone cannot satisfy the cooling
requirements of the conditioned space, economizer cool-
ing is integrated with mechanical cooling, providing
second-stage cooling. Compressor no. 1 and the
condenser fan will be energized and the position of the
economizer damper will be determined by the supply-air
temperature. Compressor no. 2 (50TFF008-014) is locked
out.
When the second stage of cooling is satisfied, the com-
pressor and condenser-fan motor will be deenergized.
The damper position will be determined by the supply-air
temperature.
When the first stage of cooling is satisfied, the damper
will move to fully closed position.
Cooling, units with EconoMi$er (50TFF007) —
When the outdoor-air temperature (OAT) is above the
ECON SP set point and the room thermostat calls for
Stage 1 cooling (R to G + Y1), the indoor (evaporator) fan
motor (IFM) is energized and the EconoMi$er damper
modulates to minimum position. The compressor contac-
tor is energized to start the compressor and outdoor (con-
denser) fan motor (OFM). After the thermostat is satisfied,
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the damper modulates to the fully closed position when the
IFM is deenergized.
When the OAT is below the ECON SP setting and the
room thermostat calls for Stage 1 cooling (R to G + Y1),
the EconoMi$er modulates to the minimum position when
the IFM is energized. The EconoMi$er provides Stage 1 of
cooling by modulating the return and outdoor-air dampers
to maintain a 12.8 C (55 F) supply air set point. If the
supply-air temperature (SAT) is greater than 13.9 C (57 F),
the EconoMi$er modulates open, allowing a greater
amount of outdoor air to enter the unit. If the SAT drops
below 11.7 C (53 F), the outdoor air damper modulates
closed to reduce the amount of outdoor air. When the SAT
is between 11.1 and 13.9 C (53 and 57 F), the
EconoMi$er maintains its position.
If outdoor-air alone cannot satisfy the cooling require-
ments of the conditioned space, and the OAT is above the
MECH CLG LOCKOUT set point, the EconoMi$er inte-
grates free cooling with mechanical cooling. This is accom-
plished by the strategies below.
NOTE: Compressor has a 2-minute Minimum On, Mini-
mum Off, and Interstage delay timer.
1. If Y1 is energized, and the room thermostat calls for
Y2 (2-stage thermostat), the compressor and OFM
are energized. The EconoMi$er damper is main-
tained at its current position.
2. If Y1 is energized for more than 20 minutes, and Y2
is not energized (whether or not a 2-stage thermostat
is used), the compressor and OFM are energized.
The EconoMi$er damper is maintained at its current
position.
3. If Y1 is energized, and the compressor is already
energized (see Step 2) and the room thermostat calls
for Y2, the compressor continues to operate.
4. If compressor is energized and the thermostat is satis-
fied, the compressor, the OFM, and IFM are deener-
gized and the EconoMi$er modulates closed.
When the OAT is below the MECH CLG LOCKOUT set
point, the compressors remain off.
Cooling, units with EconoMi$er (50TFF008-014)
— When the outdoor-air temperature (OAT) is above the
ECON SP set point and the room thermostat calls for
Stage 1 cooling (R to G + Y1), the indoor (evaporator) fan
motor (IFM) is energized and the EconoMi$er damper
modulates to minimum position. The compressor contac-
tor is energized to start the compressor and outdoor (con-
denser) fan motor (OFM). After the thermostat is satisfied,
the damper modulates to the fully closed position when the
IFM is deenergized.
When the OAT is below the ECON SP setting and the
room thermostat calls for Stage 1 cooling (R to G + Y1),
the EconoMi$er modulates to the minimum position when
the IFM is energized. The EconoMi$er provides Stage 1 of
cooling by modulating the return and outdoor-air dampers
to maintain a (12.8 C) 55 F supply air set point. If the sup-
ply-air temperature (SAT) is greater than 13.9 C (57 F), the
EconoMi$er modulates open, allowing a greater amount of
outdoor air to enter the unit. If the SAT drops below
11.7 C (53 F), the outdoor air damper modulates closed to
reduce the amount of outdoor air. When the SAT is be-
tween 11.7 and 13.9 C (53 and 57 F), the EconoMi$er
maintains its position.