Electrical data, Operating sequence typical wiring cooling, Capacity control – Carrier 48DD User Manual
Page 4: Heating, Automatic changeover, Air circulation, Intermediate season, Heating season
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ELECTRICAL DATA
OPERATING SEQUENCE
TYPICAL WIRING
Cooling
—
Power
on
and
thermostat
assembly
set
at
"Cool,”
"Fan
Auto" and desired temperature.
Step
1
of
cooling
thermostat
energizes
outdoor
and
indoor
fans
and
Time
Guard
Circuit
Time
Guard
Circuit
delays
the
start
of
the
compressor for fifteen seconds.
Step
2
of
cooling
thermostat
operates
a
second
Time
Guard
Circuit
which
delays
the
start
of
the
second
compressor
for
fifteen
seconds.
On
compressor
shutdown
for
any
reason,
Time
Guard
Circuit prevents compressor restart for at least five minutes.
Capacity Control
—
Two-step
thermostat
operates
the
compressors
as the cooling load changes.
Heating
— Turn power and gas on, and set thermostat assembly at
"Heat," "Fan Auto" and desired temperature.
The
induced
draft
motor
is
energized
whenever
unit
field
power
is
on
with
thermostat
set
for
"Heat"
or
"Auto."
No.
1
glow
coil
ignites
the
no.
1
pilot
(a
thirty-second
delay
occurs
before
glow
coil
lights
the
pilot)
Electric
pilot
shifts
to
no.
2
glow
coil
and
no.
2
pilot ignites.
After
all
pilots
ignite,
unit
is
ready
to
heat
When
step
1
of
heating
thermostat
closes:
the
gas
valve
relay
energizes,
the
main
gas
valve
opens,
the
indoor
fan
relay
(IFR
2)
closes,
the
indoor
fan
contactor
energizes,
and
the
indoor
fan
motor
starts.
Burners
are
now at 50 percent capacity.
When
step
2
of
heating
thermostat
closes
and
energizes
the
second stage of gas valve, the unit operates at full capacity.
When
call
for
heat
is
satisfied,
step
2
of
thermostat
opens,
de-energizing the second stage of the gas valve.
Unit
may
cycle
between
50
percent
and
full
capacity
as
step
2
dictates.
When
step
1
of
the
thermostat
opens,
the
gas
valve
relay
shuts off the main gas valve and indoor fan motor.
Automatic Changeover
—
When
system
selector
switch
is
set
at
"Auto,"
unit
will
automatically
change
from
heating
to
cooling
when
the
temperature
of
the
conditioned
space
rises
to
the
cooling
lever
setting.
When
the
temperature
of
the
conditioned
space
falls
to
the
heating
lever
setting,
the
unit
will
automatically
change
from
cooling to heating
The
thermostat
and
unit
are
so
connected
that
the
cooling
and
heating systems will not operate simultaneously.
Air Circulation
— With power on and unit controls set at "Off" and
"Fan,"
indoor
air
fan
operates'
continuously
for
air
circulation.
When
controls
are
set
at
"Heat"
or
"Cool"
and
"Fan,"
heating
or
cooling
is
provided
as
required,
while
indoor
fan
motor
operates
continuously.
OPERATING SEQUENCE - ACCESSORY MODULATING
OUTSIDE AIR CONTROL
Cooling Season
—
Thermostat
assembly
set
at
"Cool"
and
"Fan
Auto."
Damper
goes
to
"Vent"
when
step
1
of
cooling
thermostat
closes,
energizing
outdoor
and
indoor
fan
motors
and
the
compressors.
When
step
1
is
satisfied,
outdoor
and
indoor
fan
motors
and
the
compressor
shut
off,
and
the
outside
air
damper
closes.
(Damper
always
stays
at
"Vent"
during
cooling
sequence
if
fan
switch
is
at
"Fan," and night switch is closed.)
Intermediate Season
— Same as for cooling season, except that as
step
1
of
thermostat
closes
and
indoor
fan
motor
starts,
compressor
and
outdoor
fan
motor
remain
off
if
outside
air
temperature
is
below
outdoor
air
thermostat
setting.
If
outside
and
return
air
temperature
rises
above
or
drops
below
mixed
air
thermostat
setting,
the
outside
air
damper
will
reposition
to
maintain
the
thermostat
setting.
Damper
will
move
to
closed
position
when
cooling
step
1
is
satisified
Damper
will
move
to
"Vent"
position
when fan switch is at "Fan."
The
outside
air
damper
will
close
when
the
night
switch
is
opened (night position), or whenever the indoor fan shuts down.
Heating Season
— Damper always stays at "Vent" while fan motor is
operating. Outside air damper closes when night switch opens.
C
cc
Ccw '
CH
CR
CS
Cw
DM
FDM
FDR
GC
GV
GVR
HA
HPCT
HR
IFC
IFR
IP
LEGEND
■
Compressor Contactor
LP
■
Cooling Compensators
LS
•Counterclockwise
MAT.
■
Crankcase Heater
NS
■
Control Relay
■
Centrifugal Switch
OAT.
■
Clockwise
OFC
■
Damper Motor
OI
■
Forced Draft Motor
Pii
■
Forced Draft Relay
R
■Glow Coil
RES
■
Gas Valve
TB
■
Gas Valve Relay
TC
■
Heating Anticipator
TDR
■
Head Pressure
TH
• Control Thermostat
TM
■
Holding Relay
TRANS
■ Indoor Fan Contactor
■ Indoor Fan Relay
_______
■ Internal Protector
_______
- Low Pressure Switch
- Limit Switch
- Mixed Air Thermostat
- Night Switch
(Field supplied)
- Outside Air Thermostat
- Outdoor Fan Contactor
- Overload
■ Pilot
- Relay
- Resistance Wire
- Terminal Block
- Thermostat, Cooling
- Time Delay Relay
- Thermostat, Heating
• Timer Motor
- Transformer
Factory Wiring
Field Wiring