12HPB
Corp.9504−L1
Revised 10−2004
Service Literature
12HPB SERIES UNITS
The 12HPB is a residential split-system heat pump. The
series is designed for use with expansion valves (TXV). All
12HPB units utilize scroll compressors.
Information contained in this manual is intended for use by
qualified service technicians only. All specifications are subject
to change.
This manual is divided into sections which discuss the
major components, refrigerant system, charging procedure, maintenance and operation sequence.
12HPB series units are available in 2, 2 -1/2, 3, 3 -1/2, 4
and 5 ton capacities. All major components (indoor blower
and coil) must be matched according to Lennox recommendations for the compressor to be covered under warranty. Refer to the Engineering Handbook for approved
system matchups.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect electronic
components. Take precautions during unit installation and service to protect the unit’s electronic
controls. Precautions will help to avoid control
exposure to electrostatic discharge by putting
the unit, the control and the technician at the
same electrostatic potential. Neutralize electrostatic charge by touching hand and all tools on an
unpainted unit surface before performing any
service procedure.
WARNING
Refrigerant can be harmful if it is inhaled. Refrigerant must be used and recovered responsibly.
Failure to follow this warning may result in personal injury or death.
SPECIFICATIONS
Model No.
Outer coil
Net face area - sq.
sq ft
ft. (m2)
Outdoor
Coil
Inner coil
Tube diameter in. (mm) & no. of rows
Outdoor
Coil
F
Fan
12HPB30
12HPB36
15.21 (1.41)
15.21 (1.41)
5.44 (0.51)
14.50 (1.35)
14.50 (1.35)
5/16 (8) 1.37
5/16 (8) 2
5/16 (8) 2
18 (709)
22 (866)
22 (866)
18 (457) 3
18 (457) 4
18 (457) 4
1/6 (124)
1/6 (124)
1/6 (124)
Fins per inch (m)
Diameter in. (mm) & no. of blades
12HPB24
15.21 (1.41)
Motor hp (W)
Cfm (L/s)
2500 (1180)
2450 (1155)
2450 (1155)
Rpm
1100
1100
1100
Watts
200
200
200
*Refrigerant charge furnished (HCFC-22)
6 lbs. 14 oz. (3.11 kg)
7 lbs. 14 oz. (3.56 kg)
8 lbs. 1 oz. (3.64 kg)
Liquid line in. (mm) o.d. connection (sweat)
3/8 (9.5)
3/8 (9.5)
3/8 (9.5)
Vapor line in. (mm) o.d. connection (sweat)
3/4 (19.1)
3/4 (19.1)
7/8 (22.2)
Shipping weight lbs. (kg) 1 package
162 (73)
181 (82)
187 (85)
*Refrigerant charge sufficient for 15 ft. (4.5 m) length of refrigerant lines.
Page 1
©1997 Lennox Industries Inc.
SPECIFICATIONS (continued)
Model No.
12HPB42
12HPB48
12HPB60
Outer coil
15.21 (1.41)
21.11 (1.96)
21.11 (1.96)
Inner coil
14.50 (1.35)
20.31 (1.89)
20.31 (1.89)
5/16 (8) 2
5/16 (8) 2
5/16 (8) 2
22 (866)
22 (866)
22 (866)
18 (457) 4
22 (559) 4
22 (559) 4
1/3 (249)
1/3 (249)
1/3 (249)
2930 (1385)
3890 (1835)
3890 (1835)
Rpm
1100
1085
1085
Watts
310
375
375
8 lbs. 8 oz. (3.84 kg)
11 lbs. 12 oz. (5.32 kg)
12 lbs. 8 oz. (5.66 kg)
Liquid line in. (mm) o.d. connection (sweat)
3/8 (9.5)
3/8 (9.5)
3/8 (9.5)
Vapor line in. (mm) o.d. connection (sweat)
7/8 (22.2)
7/8 (22.2)
1-1/8 (28.6)
Shipping weight lbs. (kg) 1 package
195 (88)
259 (117)
263 (119)
Net face area - sq.
sq ft
ft. (m2)
Outdoor
Coil
Tube diameter in. (mm) & no. of rows
Fins per inch (m)
Diameter in. (mm) & no. of blades
Motor hp (W)
Outdoor
O
tdoor
Coil
Fan
Cfm (L/s)
*Refrigerant charge furnished (HCFC-22)
*Refrigerant charge sufficient for 15 ft. (4.5 m) length of refrigerant lines.
ELECTRICAL DATA
Model No.
12HPB24
12HPB30
12HPB36
12HPB42
12HPB48
12HPB60
208/230v
1ph
208/230v
1ph
208/230v
1ph
208/230v
1ph
208/230v
1ph
208/230v
1ph
Rated load amps
10.3
13.5
15.4
18.0
23.7
28.9
Power factor
.96
.96
.96
.95
.96
.96
Locked rotor amps
56.0
72.5
88.0
104.0
129.0
169.0
Full load amps
1.1
1.1
1.1
1.9
1.9
1.9
Locked rotor amps
1.9
1.9
1.9
4.1
4.1
4.1
20
30
35
40
50
60
14.0
18.0
20.4
24.4
31.5
38.0
Line voltage data 60 hz
Compressor
Outdoor Coil
Fan Motor
Rec. maximum fuse or circuit breaker size (amps)
*Minimum circuit ampacity
*Refer to National or Canadian Electrical Code manual to determine wire, fuse and disconnect size requirements.
NOTE Extremes of operating range are plus 10% and minus 5% of line voltage.
Page 2
I − UNIT COMPONENTS
24V THERMOSTAT TERMINAL STRIP
Unit components are illustrated in figure 1.
12HPB UNIT COMPONENTS
T
OUTDOOR
FAN/MOTOR
L
C
R
W1 O Y1
T" & L" connections are used only if ambient
thermistor and service light are installed in the
12HPB and the proper room thermostat is used.
Only early model units will have this feature.
CONTROL
BOX
FIGURE 3
1 − Compressor Contactor K1
SUCTION
MUFFLER
DEFROST
THERMOSTAT
REVERSING
VALVE
COMPRESSOR
CHECK/EXPANSION
VALVE
BI-FLOW
FILTER DRIER
The compressor is energized by a contactor located in the
control box. See figure 2. Single−pole and two-pole contactors are used in 12HPB series units. See wiring diagrams for specific unit. K1 is energized through the control board by the indoor thermostat terminal Y1 (24V)
when thermostat demand is present.
DANGER
Electric Shock Hazard.
May cause injury or death.
Disconnect all remote electrical power
supplies berore opening unit panel. Unit
may have multiple power supplies.
FIGURE 1
12HPB UNIT CONTROL BOX
Some units are equipped with single−
pole contactors. When unit is equipped
with a single−pole contactor, line voltage
is present at all components (even when
unit is not in operation).
DUAL CAPACITOR
(C12)
COMPRESSOR
CONTACTOR
(K1)
2 − Dual Capacitor C12
GROUNDING
LUG
The compressor and fan in 12HPB series units use permanent split capacitor motors. The capacitor is located inside the
unit control box (see figure 2). A single dual" capacitor (C12)
is used for both the fan motor and the compressor (see unit
wiring diagram). The fan side and the compressor side of the
capacitor have different MFD ratings. See table 1 for dual capacitor ratings.
DEFROST
CONTROL
(CMC1)
FIGURE 2
TABLE 1
A − Control Box (Figure 2)
12HPB units are not equipped with a 24V transformer. All
24 VAC controls are powered by the indoor unit. Refer to
wiring diagram.
Electrical openings are provided under the control box cover. Field thermostat wiring is made to a 24V terminal strip
located on the defrost control board located in the control
box. See figure 3.
Page 3
12HPB (C12) DUAL CAPACITOR RATING
Terminal
Unit
MFD
FAN
5
12HPB24
HERM
40
FAN
5
12HPB30
HERM
45
FAN
5
12HPB36/42
HERM
50
FAN
7.5
12HPB48
HERM
60
FAN
7.5
12HPB60
HERM
80
VAC
370
3 − Defrost System
12HPB units built prior to April 2002
The 12HPB defrost system includes two components: a
defrost thermostat, and a defrost control.
a − Defrost Thermostat
The defrost thermostat is mounted on the liquid line between the check/expansion valve and the distributor. When
defrost thermostat senses 35_F (2_C) or cooler, its contacts
close and send a signal to the defrost control board to start the
defrost timing. It also terminates defrost when the liquid line
warms up to 70_F (21_C).
b − Defrost Control
The defrost control board in the 12HPB series units has the
combined functions of a time/temperature defrost control, defrost relay, time delay, diagnostic LEDs and field connection
terminal strip.
The control provides automatic switching from normal heating
operation to defrost mode and back. During compressor cycle
(room thermostat demand cycle), if the O" input is not on and
the defrost thermostat is closed, the control accumulates compressor run times at 30, 60, or 90 minute field adjustable intervals. When the accumulated compressor run time ends, the
defrost relays are energized and defrost begins.
Defrost Control Timing Pins
Each timing pin selection provides a different accumulated
compressor run period during one thermostat run cycle.
The defrost interval can be adjusted to 30, 60 or 90 minutes.
See figure 4. The defrost period is a maximum of 14 minutes
and cannot be adjusted. If no timing is selected, the control defaults to 90 minutes.
A TEST option is provided for troubleshooting. When the
jumper is placed across the TEST pins, the timing of all
functions is reduced by a factor of 128. For example, a 30
minute interval during TEST is 14 seconds and the 14 minute defrost is reduced to 6.5 seconds.
The TEST mode may be started at anytime. If the jumper is in
the TEST position at power−up or for longer than five minutes,
the control will ignore the TEST selection and will default to a
90 minute interval.
Time−Delay
12HPB model units built prior to August 1996 will feature a time off delay. The timed−off delay is five minutes
long. Without the time delay it would be possible to
short cycle the compressor. A scroll compressor, when
short cycled, can run backward if head pressure is still
high. It does not harm a scroll compressor to run backward, but it could cause a nuisance tripout of safety limits (internal overload). For this reason, if a TOC delay
should fail, it must be replaced. Do not bypass the control. Later model compressors have an arrest feature
which eliminates the need for the TOC. This feature is
internally built and mechanically prevents the compressor from turning backwards.
Pressure Switch Safety Circuit
The defrost control incorporates a pressure switch safety
circuit that allows the application of up to two optional pressure switches; high pressure and/or loss of charge. See
figure 4. During a demand cycle, the defrost control will
lock out the unit on the third instance the unit goes off on
any pressure switch wired to this circuit. The diagnostic LEDs
will display a pattern for a lockout pressure switch on the third
open pressure switch occurrence. See table 2. The unit will remain locked out until 24 volt power is broken to terminal R" on
the defrost board and then remade.
Remove factory−installed jumper before connecting optional pressure switches to control board. When two pressure switches are used, wire each switch to one set of terminals PS1 and PS2 on the defrost control board. See figure 4. When only one pressure switch is used, wire the
switch to the two outside terminals of the pressure switch
connections.
NOTE: If not using a pressure switch, the factory−installed
jumper wire must be connected, or unit will not operate.
Ambient Thermistor & Service LightConnection
12HPB model units built prior to August 1996 will have a defrost control board which provides terminal connections for a
monitoring kit (part number 76F53) which includes an ambient
thermistor and a service light. The monitor kit provides a service light thermostat which activates the room thermostat service light during periods of inefficient operation. The thermistor
compensates for changes in ambient temperatures which
might cause excessive thermostat droop. Later 12HPB model
units do not have the terminal connections; however the monitoring kit can still be used. See Installation Instructions for
proper wiring.
Diagnostic LEDs
The defrost board uses two LEDs for diagnostics. The
LEDs flash a specific sequence according to the condition.
TABLE 2
DEFROST CONTROL BOARD DIAGNOSTIC LED
MODE
LED 1
LED 2
Normal Operation/
Power to board
Flash together with
LED 2
Flash together with
LED 1
Time Delay
To Protect Compressor
Alternating Flashes
with LED 2
Alternating Flashes
with LED 1
Pressure Switch Open
Off
On
Pressure Switch Lockout
On
Off
Board Malfunction
On
On
Page 4
12HPB DEFROST CONTROL BOARD
NOTE − COMPONENT LOCATIONS WILL VARY WITH BOARD MANUFACTURER
CONNECTION FOR
ONE OPTIONAL SWITCH
PRESSURE SWITCH
SAFETY CIRCUIT
CONNECTIONS
High
Pressure
Switch
DEFROST
INTERVAL
TIMING PINS
S4
CONNECTIONS FOR
TWO OPTIONAL
SWITCHES
AMBIENT
THERMISTOR
CONNECTION
SERVICE LIGHT
CONNECTION
Optional
switch
24V TERMINAL STRIP
CONNECTIONS
S4
High
Pressure
Switch
FIGURE 4
4 − Defrost System
12HPB DEFROST CONTROL BOARD
12HPB units built April 2002 and later
The defrost system includes two components: a defrost
thermostat and a defrost control.
Defrost Thermostat
The defrost thermostat is located on the liquid line between
the check/expansion valve and the distributor. When defrost thermostat senses 42°F (5.5°C) or cooler, the thermostat contacts close and send a signal to the defrost control
board to start the defrost timing. It also terminates defrost
when the liquid line warms up to 70°F (21°C).
Defrost Control
The defrost control board includes the combined functions of a time/temperature defrost control, defrost relay,
diagnostic LEDs and terminal strip for field wiring connections. See figure 5.
The control provides automatic switching from normal
heating operation to defrost mode and back. During compressor cycle (call for defrost), the control accumulates
compressor run times at 30, 60, or 90 minute field−adjustable intervals. If the defrost thermostat is closed when the
selected compressor run time interval ends, the defrost
relay is energized and defrost begins.
Page 5
HIGH PRESSURE SWITCH
SAFETY CIRCUIT
CONNECTIONS
NOTE − Remove factory−
installed jumper to add
pressure switch.
CC
Y
24V
TERMINAL
STRIP
DEFROST
INTERVAL
TIMING PINS
CONNECTION FOR
OPTIONAL
HIGH PRESSURE
SWITCH
DIAGNOSTIC
LEDs
High
Pressure
Switch
S4
FIGURE 5
Defrost Control Timing Pins
B − Compressor
Each timing pin selection provides a different accumulated compressor run time period during one thermostat
run cycle. This time period must occur before a defrost
cycle is initiated. The defrost interval can be adjusted to
30 (T1), 60 (T2), or 90 (T3) minutes. See figure 5. The defrost timing jumper is factory−installed to provide a
60−minute defrost interval. If the timing selector jumper
is not in place, the control defaults to a 90−minute defrost
interval.The maximum defrost period is 14 minutes and
cannot be adjusted.
All 12HPB units utilize a scroll compressor. The scroll compressor design is simple, efficient and requires few moving
parts. A cutaway diagram of the scroll compressor is shown in
figure 6. The scrolls are located in the top of the compressor
can and the motor is located just below. The oil level is immediately below the motor.
A TEST option is provided for troubleshooting. The TEST
mode may be started any time the unit is in the heating
mode and the defrost thermostat is closed or jumpered. If the jumper is in the TEST position at power-up, the
control will ignore the test pins. When the jumper is placed
across the TEST pins for two seconds, the control will enter
the defrost mode. If the jumper is removed before an additional 5−second period has elapsed (7 seconds total), the
unit will remain in defrost mode until the defrost thermostat
opens or 14 minutes have passed. If the jumper is not removed until after the additional 5−second period has
elapsed, the defrost will terminate and the test option will
not function again until the jumper is removed and re−applied.
The scroll is a simple compression concept centered around
the unique spiral shape of the scroll and its inherent properties.
Figure 7 shows the basic scroll form. Two identical scrolls are
mated together forming concentric spiral shapes (figure 8).
One scroll remains stationary, while the other is allowed to "orbit" (figure 9). Note that the orbiting scroll does not rotate or
turn but merely orbits the stationary scroll.
SCROLL COMPRESSOR
DISCHARGE
SUCTION
Pressure Switch Circuit
The defrost control incorporates a pressure switch circuit
that allows the application of an optional high pressure
switch. See figure 5. During a demand cycle, the defrost
control will lock out the unit if the optional high pressure
switch opens. The diagnostic LEDs will display a pattern
for an open high pressure switch. See table 3. The unit will
remain locked out until the switch resets or is reset.
FIGURE 6
NOTE − During operation, the head of a scroll compressor
may be hot since it is in constant contact with discharge gas.
SCROLL FORM
Remove the factory-installed jumper before connecting
the optional high pressure switch to the control board.
NOTE − If not using a pressure switch, the factory-installed
jumper wire must be connected.
FIGURE 7
CROSS−SECTION OF SCROLLS
Diagnostic LEDs
The defrost board uses two LEDs for diagnostics. The LEDs
flash a specific sequence according to the condition.
DISCHARGE
STATIONARY SCROLL
DISCHARGE
PRESSURE
TABLE 3
SUCTION
DEFROST CONTROL BOARD DIAGNOSTIC LED
MODE
LED 1
LED 2
Normal operation /
power to board
Synchronized
Flash with LED 2
Synchronized
Flash with LED 1
Board failure or no power
Off
Off
Board failure
On
On
High pressure switch open
Flash
On
Low pressure switch open*
On
Flash
Pressure switch lockout*
On
Off
Anti−short−cycle /
5−minute delay*
Alternating Flash
with LED 2
Alternating Flash
with LED 1
TIPS SEALED BY
DISCHARGE PRESSURE
ORBITING SCROLL
FIGURE 8
Page 6
Due to its efficiency, the scroll compressor is capable of drawing a much deeper vacuum than reciprocating compressors. Deep vacuum operation can cause internal fusite
arcing resulting in damaged internal parts and will result
in compressor failure. Never use a scroll compressor
for evacuating or pumping−down" the system. This
type of damage can be detected and will result in denial
of warranty claims.
The counterclockwise orbiting scroll draws gas into the outer
crescent shaped gas pocket created by the two scrolls (figure
9 − 1). The centrifugal action of the orbiting scroll seals off the
flanks of the scrolls (figure 9 − 2). As the orbiting motion continues, the gas is forced toward the center of the scroll and the
gas pocket becomes compressed (figure 9 − 3). When the
compressed gas reaches the center, it is discharged vertically
into a chamber and discharge port in the top of the compressor (figure 8). The discharge pressure forcing down on the top
scroll helps seal off the upper and lower edges (tips) of the
scrolls (figure 8). During a single orbit, several pockets of gas
are compressed simultaneously providing smooth continuous
compression.
The scroll compressor is tolerant to the effects of liquid return.
If liquid enters the scrolls, the orbiting scroll is allowed to separate from the stationary scroll. The liquid is worked toward the
center of the scroll and is discharged. If the compressor is replaced, conventional Lennox cleanup practices must be used.
SUCTION
The scroll compressor is quieter than a reciprocating compressor, however, the two compressors have much different sound characteristics. The sounds made by a scroll
compressor do not affect system reliability, performance,
or indicate damage.
See compressor nameplate and ELECTRICAL DATA
table on page 2 for compressor specifications.
SUCTION
1
ORBITING SCROLL
INTERMEDIATE PRESSURE
GAS
2
CRECENT SHAPED
GAS POCKET
STATIONARY SCROLL
SUCTION
POCKET
FLANKS SEALED
SUCTION
BY CENTRIFIGUAL
FORCE
SUCTION
MOVEMENT OF ORBIT
3
4
HIGH PRESURE GAS
DISCHARGE
POCKET
FIGURE 9
Page 7
C − Outdoor Fan Motor
CONDENSER FAN MOTOR
AND COMPRESSOR ACCESS
All units use single−phase PSC fan motors which require a run
capacitor. In all units, the condenser fan is controlled by
the compressor contactor.
ELECTRICAL DATA tables in this manual show specifications for condenser fans used in 12HPBs.
Access to the condenser fan motor on all units is gained
by removing the seven screws securing the fan assembly. See figure 10. The condenser fan motor is removed
from the fan guard by removing the four nuts found on
the top panel. If condenser fan motor must be replaced,
align fan hub flush with motor shaft. Drip loops should
be used in wiring when servicing motor.
FAN GUARD
Remove (7) screws
FAN
WIRING
ALIGN FAN HUB
FLUSH WITH
MOTOR SHAFT
D − Reversing Valve L1 and Solenoid
Remove (4) nuts
A refrigerant reversing valve with electromechanical solenoid is used to reverse refrigerant flow during unit operation. The reversing valve requires no maintenance. It
is not repairable. If the reversing valve has failed, it must
be replaced.
If replacement is necessary, access reversing valve by removing the outdoor fan motor. Refer to figure 10.
REMOVE (7) SCREWS
SECURING FAN GUARD.
REMOVE FAN GUARD/FAN
ASSEMBLY.
FIGURE 10
II − REFRIGERANT SYSTEM
DANGER
See figure 11 for unit refrigerant components. Refer to figure
12 and 13 for refrigerant flow in the heating and cooling
modes. The reversing valve is energized during cooling
demand and during defrost.
Make sure all power is disconnected before
beginning electrical service procedures.
12HPB REFRIGERATION COMPONENTS
SUCTION LINE
VAPOR LINE
DISCHARGE
LINE
REVERSING
VALVE
DISTRIBUTOR
DEFROST
THERMOSTAT
MUFFLER
PROCESS
COUPLING
CHECK AND
EXPANSION VALVE
FILTER/DRIER
(BI−FLOW)
PRESSURE TAP
FITTING
FIGURE 11
Page 8
LIQUID LINE
SERVICE VALVE
SUCTION LINE
VAPOR LINE
SERVICE
VALVE
12HPB COOLING CYCLE (SHOWING MANIFOLD GAUGE CONNECTIONS)
OUTDOOR UNIT
DEFROST THERMOSTAT
DISTRIBUTOR
REVERSING VALVE
EXPANSION/CHECK
VALVE
BIFLOW
FILTER / DRIER OUTDOOR
COIL
LOW
PRESSURE
INDOOR UNIT
HIGH
PRESSURE
MUFFLER
GAUGE MANIFOLD
TO
R−22
DRUM
SUCTION
SERVICE
PORT
LIQUID LINE
SERVICE
PORT
VAPOR
LINE
VALVE
COMPRESSOR
THERMOMETER
WELL
EXPANSION/CHECK
VALVE
INDOOR
COIL
NOTE − ARROWS INDICATE DIRECTION OF REFRIGERANT FLOW
FIGURE 12
12HPB HEATING CYCLE (SHOWING MANIFOLD GAUGE CONNECTIONS)
OUTDOOR UNIT
DEFROST THERMOSTAT
DISTRIBUTOR
REVERSING VALVE
EXPANSION/CHECK
VALVE
BIFLOW
FILTER / DRIER OUTDOOR
COIL
LOW
PRESSURE
INDOOR UNIT
HIGH
PRESSURE
MUFFLER
GAUGE MANIFOLD
TO
R−22
DRUM
SUCTION
SERVICE
PORT
LIQUID LINE
SERVICE
PORT
VAPOR
LINE
VALVE
COMPRESSOR
THERMOMETER
WELL
EXPANSION/CHECK
VALVE
NOTE − ARROWS INDICATE DIRECTION OF REFRIGERANT FLOW
FIGURE 13
Page 9
INDOOR
COIL
A − Plumbing
Field refrigerant piping consists of liquid and vapor lines
from the outdoor unit (sweat connections). Use Lennox
L10 (flare) or L15 (sweat) series line sets as shown in
table 4.
TABLE 4
Outdoor
Unit
Model No.
12HPB24
12HPB30
12HPB36
12HPB42
12HPB48
12HPB60
Line Set
Model No.
(L10 or
L15)
Length of
Lines
ft.
m
L10-41-20
L15-41-20
20
6
L10-41-30
L15-41-30
30
9
L10-41-40
L15-41-40
40
12
L10-41-50
L15-41-50
50
15
L10-65-30
L15-65-30
30
9
L10-65-40
L15-65-40
40
12
L10-65-50
L15-65-50
50
15
*Notavailable
Liquid Line
Outside Dia.
Vapor Line
Outside Dia.
in.
mm
in.
mm
3/8
95
9.5
3/4
19
DANGER
Do not attempt to backseat this valve. Attempts to
backseat this valve will cause snap ring to explode
from valve body under pressure of refrigerant.
Personal injury and unit damage will result.
To Close Liquid or Vapor Line Service Valve:
1 − Remove stem cap with an adjustable wrench.
2 − Using service wrench and hex head extension (5/16 for
vapor line and 3/16 for liquid line), turn stem clockwise to
seat the valve. Tighten firmly.
3 − Replace stem cap. Tighten finger tight, then tighten an
additional 1/6 turn.
LIQUID LINE SERVICE VALVE (VALVE OPEN)
INSERT HEX
WRENCH HERE
3/8
9.5
7/8
22.2
3/8
9.5
1-1/8
28.5
STEM CAP
SERVICE
PORT
OUTLET
(TO COMPRESSOR)
*Field fabricate.
B − Service Valves
SERVICE
PORT
CAP
The liquid and vapor line service valves (figures 14 and 15)
and gauge ports are accessible from outside the unit.
Each valve is equipped with a service port. The service ports
are used for leak testing, evacuating, charging and checking
charge. A schrader valve is factory installed. A service port cap
is supplied to protect the schrader valve from contamination
and serve as the primary leak seal.
NOTE-Always keep valve stem caps clean.
LIQUID LINE SERVICE VALVE (VALVE CLOSED)
RETAINING RING
STEM CAP
SERVICE
PORT
To Access Schrader Port:
1 − Remove service port cap with an adjustable wrench.
2 − Connect gauge to the service port.
3 − When testing is completed, replace service port cap.
Tighten finger tight, then an additional 1/6 turn.
INLET
(TO INDOOR COIL)
SCHRADER
VALVE
OUTLET (TO
COMPRESSOR)
INSERT HEX
WRENCH HERE
SERVICE
PORT
CAP
SCHRADER VALVE OPEN
TO LINE SET WHEN VALVE IS
CLOSED (FRONT SEATED)
INLET
(TO INDOOR COIL)
To Open Liquid or Vapor Line Service Valve:
1 − Remove stem cap with an adjustable wrench.
2 − Using service wrench and hex head extension (5/16 for
vapor line and 3/16 for liquid line), back the stem out
counterclockwise until the valve stem just touches the retaining ring.
3 − Replace stem cap and tighten finger tight, then tighten an
additional 1/6 turn.
Page 10
VALVE FRONT
SEATED
FIGURE 14
Vapor Line (Ball Type) Service Valve
A − Pumping Down System
A ball-type full service valve is used on 12HPB. Valves
are not rebuildable. If a valve has failed it must be replaced. A
ball valve is illustrated in figure 15.
The ball valve is equipped with a service port. A schrader
valve is factory installed. A service port cap is supplied to protect the schrader valve from contamination and assure a
leak free seal.
Deep vacuum operation (operating compressor
at 0 psig or lower) can cause internal fusite
arcing resulting in a damaged or failed
compressor. This type of damage will result in
denial of warranty claim.
The system may be pumped down when leak checking the
line set and indoor coil or making repairs to the line set or
indoor coil.
1− Attach gauge manifold.
2− Front seat (close) liquid line valve.
3− Start outdoor unit.
4− Monitor suction gauge. Stop unit when 0 psig is reached.
5− Front seat (close) suction line valve.
SUCTION LINE (BALL TYPE) SERVICE VALVE
(VALVE OPEN)
USE ADJUSTABLE WRENCH
ROTATE STEM CLOCKWISE 90_ TO CLOSE
ROTATE STEM COUNTER-CLOCKWISE 90_ TO OPEN
STEM CAP
OUTLET
(TO
COMPRESSOR)
CAUTION
B − Leak Testing (To Be Done
Before Evacuating)
STEM
BALL
(SHOWN OPEN)
INLET
(FROM INDOOR COIL)
1− Attach gauge manifold and connect a drum of dry nitrogen to center port of gauge manifold.
2− Open high pressure valve on gauge manifold and
pressurize line set and indoor coil to 150 psig (1034
kPa).
3− Check lines and connections for leaks.
SERVICE
PORT
CAP
NOTE-The preferred method is to use an electronic leak or
Halide detector. Add a small amount of R22 (3 to 5 psig
[20kPa to 34kPa]) then pressurize with nitrogen to 150 psig.
4− Release nitrogen pressure from the system, correct any
leaks and recheck.
SERVICE PORT
SCHRADER CORE
FIGURE 15
III − CHARGING
The unit is factory−charged with the amount of R−22 refrigerant indicated on the unit rating plate. This charge is
based on a matching indoor coil and outdoor coil with a 15
foot (4.5 m) line set. For varying lengths of line set, refer to
table 5 for refrigerant charge adjustment. A blank space is provided on the unit rating plate to list actual field charge.
DANGER
When using dry nitrogen, a pressure reducing regulator must be used to prevent excessive pressure
in gauge manifold, connecting hoses, and within
the system. Regulator setting must not exceed 150
psig (1034 kpa). Failure to use a regulator can
cause equipment failure resulting in injury or
death.
IMPORTANT
If line length is greater than 15 feet (4.5 m) add this
amount. If line length is less than 15 feet (4.5 m),
subtract this amount.
TABLE 5
LIQUID LINE
SET DIAMETER
1/4 in. (6 mm)
5/16 in. (8mm)
3/8 in. (10 mm)
Ounce per 5 foot (ml per mm) adjust
from 15 foot (4.5 m) line set*
1 ounce per 5 feet (30 ml per 1524 mm)
2 ounce per 5 feet (60 ml per 1524 mm)
3 ounce per 5 feet (90 ml per 1524 mm)
C − Evacuating the System
1− Attach gauge manifold. Connect vacuum pump (with vacuum gauge) to center port of gauge manifold. With both
manifold service valves open, start pump and evacuate
indoor coil and refrigerant lines.
*If line set is greater than 15 ft. (4.5 m) add this amount. If line set
is less than 15 feet (4.5 m) subtract this amount
Units are designed for line sets up to 50 feet (15.2 m).
Consult Lennox Refrigerant Piping Manual for line sets
over 50 feet (15.2 m).
Page 11
IMPORTANT
A temperature vacuum gauge, mercury vacuum
(U−tube), or thermocouple gauge should be used.
The usual Bourdon tube gauges are not accurate
enough in the vacuum range.
IMPORTANT
IMPORTANT
The compressor should never be used to evacuate a refrigeration or air conditioning system.
2− Evacuate the system to 29 inches (737mm) vacuum.
During the early stages of evacuation, it is desirable to
stop the vacuum pump at least once to determine if there
is a rapid loss of vacuum. A rapid loss of vacuum would
indicate a leak in the system and a repeat of the leak
testing section would be necessary.
3− After system has been evacuated to 29 inches
(737mm), close gauge manifold valves to center port,
stop vacuum pump and disconnect from gauge manifold. Attach an upright nitrogen drum to center port of
gauge manifold and open drum valve slightly to purge
line at manifold. Break vacuum in system with nitrogen pressure by opening manifold high pressure
valve. Close manifold high pressure valve to center
port.
The following procedures require accurate
readings of ambient (outdoor) temperature, liquid
temperature and liquid pressure for proper
charging. Use a thermometer with accuracy of
+2°F( + 1.1°C) and a pressure gauge with accuracy
of +5PSIG ( + 34.5kPa).
For best results, indoor temperature should be between
70°F and 80°F (21°C and 27°C) . If outdoor temperature is
60°F (16°C) or above the approach method of charging is
used. If outdoor temperature is less than 60°F (16°C) the
subcooling method of charging is used. Slight variations in
charging temperature and pressure should be expected.
Large variations may indicate a need for further servicing.
4− Close nitrogen drum valve and disconnect from
gauge manifold center port. Release nitrogen pressure from system.
5− Connect vacuum pump to gauge manifold center
port. Evacuate system through manifold service
valves until vacuum in system does not rise above
.5mm of mercury absolute pressure or 500 microns
within a 20−minute period after stopping vacuum pump.
6− After evacuation is complete, close manifold center port,
and connect refrigerant drum. Pressurize system
slightly with refrigerant to break vacuum.
D − Charging
Charging must be done in the cooling mode. If the system is completely void of refrigerant, the recommended
and most accurate method of charging is to weigh the refrigerant into the unit according to the total amount shown on
the unit nameplate. Also refer to the SPECIFICATIONS tables
on pages 1 and 2.
If weighing facilities are not available or if unit is just low on
charge, the following procedure applies.
Page 12
APPROACH METHOD (TXV SYSTEMS)
(Ambient Temperature of 60_F [16_C] or Above)
1 − Connect gauge manifold. Connect an upright R−22
drum to center port of gauge manifold.
2 − Record outdoor air (ambient) temperature.
3 − Operate indoor and outdoor units in cooling mode. Allow outdoor unit‘ to run until system pressures stabilize.
4 − Make sure thermometer well is filled with mineral oil
before checking liquid line temperature.
5 − Place thermometer in well and read liquid line temperature. Liquid line temperature should be warmer
than the outdoor air temperature. Table 6 shows how
many degrees warmer the liquid line temperature
should be.
Add refrigerant to lower liquid line temperature.
Recover refrigerant to raise the liquid line temperature.
Add refrigerant slowly as the unit approaches the
correct temperature. This will allow refrigerant to stabilize allowing the correct temperature to be read.
TABLE 6
APPROACH METHOD
AMBIENT TEMPERATURE OF 60 _F (16 _C) OR ABOVE
Model
12HPB24
12HPB30
12HPB36
12HPB42
12HPB48
12HPB60
LIQUID LINE_F − OUTDOOR AMBIENT_F
6°F (3.3°C)
11°F (6.1°C)
12°F (6.7°C)
10°F (5.6°C)
9°F (5.0°C)
8°F (4.4°C)
TABLE 7
Outdoor Coil
Air Entering
Temp.
_F (_C)
65 (183.)
75 (23.9)
85 (29.4)
95 (35)
105 (40.6)
12HPB24
liq.
vap.
+10
+5
PSIG
PSIG
144
78
170
79
199
80
228
81
261
82
12HPB30
liq.
vap.
+10
+5
PSIG
PSIG
140
76
164
77
194
78
224
79
259
80
12HPB36
liq.
vap.
+10
+5
PSIG
PSIG
152
74
178
76
208
77
238
78
275
81
12HPB42
liq.
vap.
+10
+5
PSIG
PSIG
152
75
179
76
210
77
241
78
278
79
12HPB48
liq.
vap.
+10
+5
PSIG
PSIG
146
75
171
77
198
78
229
79
268
81
12HPB60
liq.
vap.
+10
+5
PSIG
PSIG
146
73
175
74
206
75
237
76
275
77
NOTE − Typical pressures only. Indoor evaporator match up, indoor air quantity, and evaporator load will cause the pressures to vary.
SUBCOOLING METHOD (TXV SYSTEMS)
(Ambient Temperature Below 60_F [16_C]
NOTE- It may be necessary to restrict air flow in order to
reach liquid pressures in the 200-250 psig range which
are required for checking charge. The indoor temperature
should be above 70_F (21_C). Block equal sections of air
intake panels, moving obstructions sideways until liquid
pressures in the 200-250 psig range are reached.
1 − Connect gauge manifold. Connect an upright R−22
drum to center port of gauge manifold.
2 − Operate indoor and outdoor units in cooling mode.
Allow outdoor unit to run until system pressures stabilize.
3 − Make sure thermometer well is filled with mineral oil
before checking liquid line temperature.
4 − Read liquid line pressure and convert to condensing temperature using temperature/pressure conversion chart.
Condensing temperature (read from gauges)
should be warmer than the liquid line temperature.
5 − Place thermometer in well and read liquid line temperature. Table 8 shows how much warmer the condensing temperature should be.
Add refrigerant to lower liquid line temperature.
Recover refrigerant to raise the liquid line temperature.
6 − When unit is properly charged liquid line pressures should approximate those given in table
7.
TABLE 8
IMPORTANT
Use table 7 as a general guide for performing maintenance checks. Table 7 is not a procedure for charging the system. Minor variations in these pressures
may be expected due to differences in installations.
Significant deviations could mean that the system is
not properly charged or that a problem exists with
some component in the system. Used prudently,
table 7 could serve as a useful service guide.
E − Oil Charge
See compressor nameplate.
IV − MAINTENANCE
At the beginning of each heating or cooling season, the
system should be cleaned as follows:
SUBCOOLING METHOD
AMBIENT TEMPERATURE BELOW 60 _F (16 _C)
Model
Condensing Temp°F Warmer Than Liquid Line
12HPB24
12HPB30
12HPB36
12HPB42
12HPB48
12HPB60
11°F (6.1°C)
5°F (2.8°C)
3°F (1.7°C)
4°F (2.2°C)
4°F (2.2°C)
6°F (3.3°C)
Page 13
A − Outdoor Unit
1 − Clean and inspect condenser coil. (Coil may be
flushed with a water hose).
NOTE − Make sure all power is disconnected before
flushing coil with water.
2 − Visually inspect all connecting lines, joints and
coils for evidence of oil leaks.
NOTE-Outdoor fan motors are permanently
lubricated.
B − Indoor Coil
1 − Clean coil if necessary.
2 − Check connecting lines and coil for evidence of oil
leaks.
3 − Check condensate line and clean if necessary.
C − Indoor Unit
1 − Clean or change filters.
2 − Bearings are pre-lubricated and need no further oiling.
3 − Check all wiring for loose connections.
4 − Check for correct voltage at unit.
5 − Check amp−draw on blower motor.
LOW VOLTAGE FIELD WIRING FOR 12HPB SERIES UNITS WITH CB19/CBH19/ECB19,
CB29M/ CB30M/ ECB29 COIL & TYPICAL ROOM THERMOSTAT
"T" & "L" connections used only if
field provided & installed ambient
compensating thermistor & service
light thermostat are installed in the
12HPB unit & proper t’stat is used.
Earlier 12HPB units only will have
the"T" & "L" connections.
1
Common terminal "C"
or "X" used only on
some thermostats.
BLOWER COIL
WITH ELECTRIC HEAT
LOW VOLTAGE TERMINAL
STRIP
2
3
3
4
4
1
Thermostat heat anticipation
setting 0.4 amp electric heat
for thermostats with adjustable anticipators.
2
If outdoor thermostat is used,
remove jumper between terminals
"R" & "W2".
Emergency heat relay (used only if
outdoor t’ stat is used) field provided
& installed near indoor unit, 24VAC,
5VA max, NEC Class 2
When thermostat with 2 stages
of auxilary heat is used,
connect second stage aux. heat
to terminal "W2" & remove
jumper between terminals "R"
& " W".
LOW VOLTAGE FIELD WIRING FOR 12HPB SERIES UNITS
WITH B24/ECB24 BLOWER COIL & TYPICAL ROOM THERMOSTAT
"T" & "L" connections used only if
field provided & installed ambient
compensating thermistor & service
light thermostat are installed in the
12HPB unit & proper t’stat is used.
Earlier 12HPB units only will have
the"T" & "L" connections.
Common terminal "C" or
"X" used only on some
thermostats.
TermInals "Y2" & "W2" require no
connection. they are junction terminals only & have no internal
connection to the B24.
Page 14
V − WIRING DIAGRAM AND SEQUENCE OF OPERATION
12HPB 2 THROUGH 5 TON UNIT WIRING
Page 15
12HPB 2 THROUGH 5 TON UNIT WIRING
Page 16
12HPB 2 THROUGH 5 TON UNIT WIRING
Page 17
12HPB 1-1/2 THROUGH 5 TON OPERATING SEQUENCE
This is the sequence of operation for 12HPB series units.
The sequence is outlined by numbered steps which correspond to circled numbers on the adjacent diagram.
NOTE− The thermostat used may be electromechanical or electronic.
NOTE− Transformer in indoor unit supplies power (24
VAC) to the thermostat and outdoor unit controls.
COOLING:
1 − Internal thermostat wiring energizes terminal O by
cooling mode selection, energizing the reversing valve
L1. Cooling demand initiates at Y1 in the thermostat.
2 − 24VAC energizes compressor contactor K1.
3 − K1-1 N.O. closes, energizing compressor (B1) and outdoor fan motor (B4).
4 − Compressor (B1) and outdoor fan motor (B4) begin immediate operation.
END OF COOLING DEMAND:
5 − Cooling demand is satisfied. Terminal Y1 is de-energized.
6 − Compressor contactor K1 is de-energized.
7 − K1-1 opens and compressor (B1) and outdoor fan
motor (B4) are de-energized and stop immediately.
8 − Terminal O is de−energized when internal thermostat is
out of cooling mode, de−energizing the reversing valve
L1.
FIRST STAGE HEAT:
9 − Heating demand initiates at Y1.
10 − 24VAC energizes compressor contactor K1.
11 − K1-1 N.O. closes, energizing compressor and
outdoor fan motor.
12 − Compressor (B1) and outdoor fan motor (B4) begin immediate operation.
END OF FIRST STAGE HEAT:
13 − Heating demand is satisfied. Terminal Y1 is deenergized.
14 − Compressor contactor K1 is de-energized.
15 − K1-1 opens and compressor (B1) and outdoor
fan motor (B4) are de-energized and stop immediately.
DEFROST MODE:
16 − During heating operation when outdoor coil temperature drops below 35_F (2_C) or 42_(5.5_C) see defrost system description for specific unit dash number
defrost switch (thermostat) S6 closes.
17 − Defrost control CMC1 begins timing. If defrost
thermostat (S6) remains closed at the end of the
30,60 or 90 minute period, defrost relay energizes
and defrost begins.
18 − During defrost CMC1 energizes the reversing valve
and W1 on the terminal strip (operating indoor unit on
the first stage heat mode), while de-energizing outdoor
fan motor B4.
19 − Defrost continues 14 + 1 minutes or until thermostat
switch (S6) opens. When defrost thermostat opens,
defrost control timer loses power and resets.
20 − When CMC1 resets, the reversing valve and W1 on the
terminal strip are de-energized, while the outdoor fan
motor B4 is energized.
21 − When CMC1 resets, the reversing valve and W1 on the
terminal strip are de-energized, while the outdoor fan
motor B4 is energized.
Page 18