Page 1
SERVICE
N
)
12.6
12.6
12.6
14.7
Outd
Coil
UNIT
INFORMATION
Corp. 9427–L10
Replaces Corp. 9329–L4
10HP SERIES UNITS
10HP
Litho U.S.A.
The 10HP is a high-efficiency residential
split-system heat pump. Extra large outdoor coil,
coil circuiting and high outdoor coil air volume
result in a high SEER rating (minimum of 10.0).
10HP12 through 10HP48 units are designed for use
with an expansion valve or RFCIII system in the
indoor unit. 10HP60 units are designed for use with
an expansion valve only in the indoor unit.
All compressors are hermetically sealed for
trouble-free operation and long service life.
Compressor components are spring mounted within
the sealed housing. The compressor is installed in the
unit on resilient rubber mounts to assure quiet,
vibration-free operation. A built-in limit protects the
compressor from excessive current and temperatures.
10HP18 through 10HP60 models are furnished with
crankcase heaters as standard equipment. The heater
prevents liquid from accumulating in the compressor.
The heater is temperature-actuated and operates only
when required. A crankcase heater for 10HP12 units is
optional, but suction accumulator is factory installed.
This manual is divided into sections which discuss the
major components, refrigerant system, charging
procedure, maintenance, and operation sequence.
Canadian specifications are marked (CAN).
All specifications in this manual are subject to change.
Several models are available in sizes ranging from 1
through 5 tons.
SPECIFICATIONS
Model No. 10HP12 10HP18 10HP24 10HP30-1 10HP30-2
oor
Coil
Outdoor
Fan
Refrigerant — 22 charge furnished 5 lbs. 3 oz. 5 lbs. 6 oz. 6 lbs. 2 oz. 7 lbs. 3 oz
Liquid line (o.d. in.) connection (sweat) 3/8 3/8 3/8 3/8
Vapor line (o.d. in.) connection (sweat) 1/2 5/8 5/8 3/4
Line voltage data – 60hz 208-230v—1ph
Compressor rated load amps 5.0 8.1 10.9 12.2 13.7
Rec. max. fuse or circuit breaker size (amps) 15 15 25 25 30
*Minimum circuit ampacity 7.4 11.3 14.8 16.4 18.2
*Refer to National Electric Code manual to determine wire, fuse and disconnect size requirements.
NOTE – Extremes of operating range are plus 10% and minus 5% of line voltage.
3/8 in. x 1/4 in. reducer furnished to adapt to 1/4 in. field fabricated line set.
3/8 in. x 5/16 in. reducer furnished to adapt unit to 5/16 in. line set.
et face area (sq. ft.
Tube diameter (in.) & no. of rows 3/8 — 1 3/8 — 1 3/8 — 1 3/8 — 1
Fins per inch 20 20 20 20
Diameter (in.) & no. of blades 20 — 3 20 — 3 20 — 3 20 — 3
Motor hp 1/6 1/6 1/6 1/6
Cfm 2630 2630 2630 2665
Rpm 840 840 840 850
Watts 210 210 210 210
Full load amps 1.1
Page 1
1994 Lennox Industries Inc.
Page 2
SPECIFICATIONS (continued)
Net f
)
Model No. 10HP36 10HP36-4 10HP42 10HP48 10HP60
Outdoor
Coil
Outdoor
Fan
Refrigerant — 22 charge furnished
Liquid line (o.d. in.) connection (sweat) 3/8 3/8 3/8 3/8 3/8
Vapor line (o.d. in.) connection (sweat) 3/4 3/4 7/8 7/8 1-1/8
Line voltage data — 60hz
Compressor rated load amps 16.3 16.2 18.6 24.4 30.8
Rec. max. fuse or circuit breaker size (amps) 35 35 40 50 60
*Minimum circuit ampacity 21.5 21.3 25.0 32.2 40.2
*Refer to National Electric Code manual to determine wire, fuse and disconnect size requirements.
NOTE – Extremes of operating range are plus 10% and minus 5% of line voltage.
ace area (sq. ft.
Tube diameter (in.) & no. of rows 3/8 — 1.3 3/8 — 1.3 3/8 — 1 3/8 — 1.3 3/8 — 2
Fins per inch 20 20 20 20 20
Diameter (in.) & no. of blades 20 — 3 20 — 3 24 — 4 24 — 4 24 — 4
Motor hp 1/6 1/6 1/4 1/4 1/4
Cfm 2600 2600 3980 3980 3950
Rpm 845 845 840 830 825
Watts 200 200 350 340 370
Full load amps 1.1
I – UNIT INFORMATION
10HP units are available in 1, 1 -1/2, 2, 2 -1/2, 3, 3 -1/2, 4
and 5 ton capacities.
All major components (indoor blower/coil) must be
matched according to Lennox recommendations for
Outer coil 14.7 14.7 20.0 20.0 20.0
Inner coil 3.9 3.9 - - - - 6.3 19.0
7 lbs. 5 oz. (-1)
7 lbs. 7 oz. (CAN)
7 lbs. 14 oz. 8 lbs. 3 oz. 9 lbs. 6 oz. 12 lbs. 13 oz.
208/230v -1ph
the Engineering Handbook for approved system
matchups. A misapplied system will cause erratic
operation and can result in early compressor failure.
II – UNIT COMPONENTS
Unit components are illustrated in figure 1.
the compressor to be covered under warranty. Refer to
EXPANSION
VALVE
CONTROL BOX
10HP 12, 18, 24, 30 and 36
COMPRESSOR
10HP12 SHOWN
REVERSING VALVE
10HP UNIT COMPONENTS
OUTDOOR
FAN/MOTOR
SUCTION
MUFFLER 10HP12
ONLY
ACCUMULATOR
10HP12 ONLY
EXPANSION
VALVE
CONTROL BOX
FIGURE 1
10HP42, 48, and 60
FAN
SPIDER
REVERSING VALVE
OUTDOOR
FAN/MOTOR
COMPRESSOR
ACCUMULATOR
Page 2
Page 3
A – Control Box (Figure 2)
START CAPACITOR
DEFROST
RELAY (K4)
COMPRESSOR
CONTACTOR
(K1)
GROUNDING
LUG
A low voltage make up area is provided for thermostat
field wiring. Field thermostat wiring is made to color
coded pigtail connections as illustrated in figure 3.
THERMOSTAT WIRING IDENTIFICATION
YELLOW
ORANGE
BEIGE
FROM OUTDOOR UNIT
BLACK
10HP UNIT CONTROL BOX
(C7)
FIGURE 2
RED
FIGURE3
DUAL CAPACITOR
(C12)
POTENTIAL
RELAY (K31)
DEFROST
CONTROL
CMC1
TIMED OFF
CONTROL (A4)
10HP60 ONLY
LOW VOLTAGE
MAKEUP AREA
24V (POWER) INPUT
TO OUTDOOR UNIT
(COMPRESSOR)
(REVERSING VALVE)
INPUT
(ELECTRIC HEAT)
DEFROST OUTPUT
(COMMON)
INPUT
TO INDOOR UNIT/
DANGER
Shock Hazard
All 10HP units use single-pole
contactors. One leg of compressor,
capacitor and outdoor fan are
connected to line voltage at all
times. Potential exists for electrical
shock resulting in injury or death.
Remove all power at disconnect
before servicing.
Can cause personal injury or death.
1 – Compressor Contactor K1
The compressor is energized by a contactor located in
the control box. See figure 2. Contactors are SPST in
single phase units and 3PST in three phase units. K1 is
energized by the indoor thermostat terminal Y (24V).
10HP units are not equipped with a line voltage to 24V
transformer. All 24 VAC controls are powered by the
indoor unit. Refer to unit wiring diagram.
2 – Dual Capacitor C12
The compressor and fan in 10HP 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.
TABLE 1
10HP (C12) DUAL CAPACITOR RATING
Unit MFD VAC
10HP12
10HP18, 24 and
30-2
10HP30-1 and 36
10HP36-4
10HP42
10HP48 and 60
Terminal
FAN
HERM
FAN
HERM
FAN
HERM
FAN
HERM
FAN
HERM
FAN
HERM
5
25
5
35
5
45
5
40
10
40
10
60
3 – Potential Relay K31 (Start)
All 10HP units use a potential relay which controls the
operation of the starting circuit. The potential relay is
located inside the unit control box (see figure 2). The
relay is normally closed when contactor K2 is
de-energized. When K1 energizes, the compressor
immediately begins start-up. K31 remains closed
during compressor start-up and start capacitor C7
remains in the circuit. As the compressor gains speed,
THERMOSTAT
K31 is energized. When K31 energizes, the contacts
open and start capacitor C7 is taken out of the circuit.
4 – Start Capacitor C7
All 10HP units use a start capacitor (C7). C7 is located
inside the unit control box (see figure 2). C7 is wired in
parallel with the compressor side of the dual
capacitor. See table 2 for start capacitor ratings.
TABLE 2
10HP START CAPACITOR RATING (C7)
Unit MFD VAC
10HP12, 18 and 24
10HP30-1 and 36 88–108 330
10HP30-2 145–175 330
10HP36 (CAN)
10HP36-4
10HP42 and 48
10HP60 270-324 330
88–108 250
189-227 330
5 – Timed Off Control A4
A timed off control (A4) located in the control box is
used on 10HP60 units. See figure 2. The time delay is
electrically connected between thermostat terminal Y
and the compressor contactor. After cooling demand
has stopped, A4 begins counting for five minutes.
During the timing period, A4 disables the compressor
contactor. Thermostat demand will have no effect on
the unit.The unit cannot operate. After the delay, the
compressor contactor can be energized.
370
440
25088–108
Page 3
Page 4
DANGER
Do not attempt to repair this control. Unsafe
operation will result. If the control has failed,
replace the control.
6 – Defrost Relay K4
The defrost relay controls defrost. The relay is a 3PDT
relay powered 24 VAC from the thermostat. K4 is
enabled during both cooling and heating modes
(except emergency heat). It is only powered when the
defrost control is calling for defrost. When energized,
the reversing valve and indoor auxiliary heat are
energized. Simultaneously, the outdoor fan is
de-energized. K4 latches in for the duration of the
defrost period. Refer to unit wiring diagram and
operation sequence in the back of this manual.
7 – Defrost Control CMC1
The CMC1 defrost control (figure 4) is a solid state control
manufactured by Hamilton Standard. The control
provides automatic switching from normal heating
operation to defrost mode and back. The control
provides 14 minute defrost periods at 30, 60 or 90 minute
field changeable intervals. The control monitors
thermostat demand and “holds” the timer in place
between thermostat demand. A set of diagnostic pins are
also provided for troubleshooting the unit.
The control contains a solid state timer which switches
an external defrost relay through 1/4” male spades
mounted on the control’s circuit board. When the
defrost thermostat closes (call for defrost), the defrost
timer initiates a 30, 60 or 90 minute (depending on how
the control is preset) timing sequence. If the defrost
thermostat remains closed when the timing sequence
ends, the defrost relay is energized and defrost begins.
(14 minutes) cannot be changed. To change the
interval between defrosts, simply remove the
jumper from the pin it is connected to and
reconnect the jumper to one of the other available
pins (see figure 5).
TABLE 3
CMC1 DEFROST
CONTROL
TIMINGS
NORMAL
OPERATION
“TST” PINS
JUMPER
TOGETHER
INTERVAL BETWEEN DEFROSTS
WITH JUMPER CONNECTED TO:
30 60 90
30 + 3 60 + 6 90 + 9 14 + 1.4
MIN. MIN. MIN. MIN.
0.7 14 + 1.4 21 + 2.1 3.3 + 0.3
7 +
SEC. SEC. SEC. SEC.
DEFROST
TIME
DEFROST CONTROL TIMING CHANGES
WARNING – AVOID CONTACT WITH OTHER CONTROL TERMINALS OR CONTROL COMPONENTS.
WARNING – DO NOT CONNECT
TIMING JUMPER TO EITHER
TO CHANGE CONTROL TIMINGS:
1– Turn off all power to the unit to avoid circuit board damage.
2– Grasp wire connector firmly with fingers.
3–
4– Select new timing pin. DO NOT SELECT A “TST” PIN.
5– Gently push connector onto desired pin (see Table 3 for timings).
6– Turn on power to unit.
“TST” PIN.
Gently
pull connector from pin.
FIGURE 5
2– Timing Jumper
The timing jumper is a factory installed jumper
on the circuit board used to connect pin W1 to
one of the three timing pins. The jumper may be
connected to any one of the timing pins but must
never be connected to either of the “TST” pins.
See Caution below.
SOLID STATE DEFROST CONTROL CMC1
Timing Pins
Timing
Jumper
Troubleshooting Pins
30 60 90
FIGURE 4
Defrost Control Components
1– Timing Pins 30, 60, 90
Each of these pins provides a different timed
interval between defrosts. A jumper connects the
pins to circuit board pin W1. Table 3 shows the
timings of each pin. The defrost interval can be field
changed to 30, 60 or 90 minutes. The defrost period
Control Terminals
CAUTION
3– “COM” Terminal
Terminal “COM” provides 24VAC Common.
4– “HLD” Terminal
Terminal “HLD” holds the internal timer in place
between thermostat demands and allows the unit to
continue timing upon resumption of thermostat
demand. Terminal “HLD” is connected directly to
thermostat demand.
NOTE – Hold function operates between thermostat
demands only when defrost thermostat is closed. This
is the only time that the timer is operating.
Page 4
Page 5
5– “24V” Terminal
Terminal “24V” receives 24VAC from the control
transformer through the defrost thermostat. This
terminal powers the control’s internal timer and
relays. Terminal “24V” is powered only when there
is a call for defrost (defrost thermostat closed). The
timer begins timing at 0 only after terminal “24V”
receives power.
6– “OUT” Terminal
Terminal “OUT” controls defrost when connected
to one side of the defrost relay coil. An internal
relay connected to terminal “OUT” closes to allow
external defrost relay to energize and initiate
defrost. At the end of the defrost period, the
internal relay connected to terminal “OUT” opens
to de-energize the external defrost relay.
A defrost period can last up to 14 minutes and can be
terminated two ways. If the defrost thermostat does
not open within 14 minutes after defrost begins, the
timer will de–energize the defrost relay and the unit
will resume normal operation. If the defrost
thermostat opens during the 14 minute defrost period,
the defrost relay is de–energized and the unit resumes
normal operation. Refer to figure 7.
DEFROST CONTROL TEST MODE
WARNING – AVOID CONTACT WITH OTHER CONTROL
TERMINALS OR CONTROL COMPONENTS.
7– “TST” Pins
Each board is equipped with a set of test pins for
use in troubleshooting the unit. When jumpered
together, these pins reduce the control timing to
about 1/256 original time (see table 3 and figure 6).
IMPORTANT
Control will begin test mode only if normal load is
applied to control terminals. Do not attempt to
operate or test control out of unit.
10HP SERIES UNITS TYPICAL DEFROST TIMINGS
defrost timer resets and “HOLD” function stops.
NORMAL HEATING OPERATION: DEFROST TERMINATED BY TIME
30/60/90 MINUTES 14 MIN. 30/60/90 MINUTES
30/60/90 MINUTES
CLOSED, ON
OPEN, OFF
THERMOSTAT DEMAND
DEFROST THERMOSTAT
THERMOSTAT DEMAND
DEFROST THERMOSTAT
THERMOSTAT DEMAND
DEFROST THERMOSTAT
THERMOSTAT DEMAND
DEFROST THERMOSTAT
Note – Control begins timing at 0 when defrost thermostat closes. Defrost is terminated when defrost
relay is de–energized. Anytime defrost thermostat opens, defrost relay is immediately de–energized,
NORMAL HEATING OPERATION: DEFROST TERMINATED BY DEFROST THERMOSTAT
DEFROST RELAY
DEFROST RELAY
NORMAL HEATING OPERATION INTERRUPTED BY THERMOSTAT DEMAND: “HOLD” FUNCTION
DEFROST RELAY
DEFROST PERIOD INTERRUPTED BY THERMOSTAT DEMAND: “HOLD” FUNCTION
DEFROST RELAY
TO PLACE CONTROL IN TEST MODE:
1– Turn off all power to avoid damaging the circuit board.
2– Make sure all control terminals are connected as shown on
unit wiring diagram before attempting to place control in
test mode. See NOTE below.
NOTE – Control will not go into test mode when disconnected from unit. Unit load must be applied to control terminals before the control will go into test mode.
3– Connect jumper to “TST” pins as shown.
4– Turn indoor thermostat to heat mode and adjust to highest
temperature setting.
5– Turn on power to unit.
6– See Table 3 for control timings in “TST” mode.
7– Be sure to turn off power and remove jumper when test is
complete. Turn on power and re–adjust thermostat.
30/60/90 MINUTES
30/60/90 MINUTES PLUS “HOLD” TIME
“HOLD” TIME
“HOLD” TIME
14 MIN. PLUS “HOLD” TIME
FIGURE 7
FIGURE 6
DEFROST THERMOSTATOPEN WITHIN 14 MINUTES
DEFROST THERMOSTAT
MUST REMAIN CLOSED
FOR TIMER TO REMAIN
IN “HOLD”
DEFROST THERMOSTAT
MUST REMAIN CLOSED
FOR TIMER TO REMAIN
IN “HOLD”
Page 5
Page 6
B – Compressor
Table 4 shows the specifications of compressors used
in 10HP series units.
TABLE 4
10HP COMPRESSOR SPECIFICATIONS
Unit
10HP12 1 26.3 4.8
10HP18
10HP24 1 61 32*9.2
10HP30-1 1 71.0 32*11.7
10HP30–2
10HP36 1 86.7 54*14.2
10HP36-4 1 96 55*16.2
10HP36 (CAN) 1 40*
10HP42 1 102 55*20.4
10HP48
10HP60 1 147 24.0 65*
*Shipped with conventional white oil (Sontex 200LT) or 3GS. 3GS oil may
be used if additional oil is required.
**Shipped with 60% Zerol 300—40% Sontex 200LT. Zerol 300 may be used
if additional oil is required.
Voltage
208/230
208/230
208/230
208/230
208/230
208/230
208/230
208/230
208/230
208/230
208/230
Phase LRA RLA Oil fl.oz.
15**
1
1
1
49
75.0
13.7
94 14.5
135
19.0
32*6.8
45*
65*
1 – Rotary Compressor (10HP12 Units Only)
10HP12 units utilize a hermetically sealed rotary-type
compressor manufactured by Tecumseh Products. It is
illustrated in figure 8.
The compressor has four
ROTARY COMPRESSOR
moving parts: a rotor
shaft, eccentric, roller
and a blade. See figure 9.
The compressor rotor
shaft is attached directly
to the compressor motor.
The rotor shaft is
permanently attached to
an eccentric. The
eccentric is inside the
roller and as the eccentric
rotates, the roller rotates.
The spring loaded blade
is in continuous contact
with the roller. The
COMPRESSOR IS MANUFACTURED BY
contact and a thin layer of
oil form a seal separating
the suction port from the discharge port at all times.
ROTARY COMPRESSOR INTERNALS
ROLLER
BLADE
FIGURE 9
10HP12
TECUMSEH PRODUCTS
FIGURE 8
ROTOR
SHAFT
ECCENTRIC
Figure 10 illustrates the four steps in a rotary
compressor’s continuous intake cycle. The spring-loaded
blade is compressed fully at the beginning of an exhaust
cycle. At this instant the compression is beginning (1).
The roller rotates and compression continues (2). The
suction port is always separated from the discharge port
(3). Intake continues and the compressed vapor is
discharged (4).
ROTARY COMPRESSOR OPERATION
12
COMPRESSION
CONTINUES
COMPLETION
OF INTAKE
BEGINNING OF
COMPRESSION
INTAKE
CONTINUES
AND
DISCHARGE
BEGINS
34
COMPRESSED
VAPOR
INTAKE
CONTINUES
COMPRESSION
CONTINUES
INTAKE
CONTINUES
FIGURE 10
a – Suction Muffler (10HP12 Units Only)
All 10HP12 units are equipped with a suction
muffler that is externally mounted on the
compressor shell and attached to the suction
line. The muffler contains two wire mesh
filters for added compressor protection. Refer
to figures 1 and 20.
2 – Accumulator
All 10HP12, 42, 48 and 60 units are equipped with an
accumulator that is mounted in the suction line. The
accumulator protects the compressor from liquid
slugging. Refer to figures 1 and 21.
3 – Reciprocating Compressor (all other units)
All units except the 10HP12 units utilize a conventional
reciprocating compressor.
4 – Crankcase Heater
A crankcase heater is used on all 10HP18 through 10HP60
models. The well-mounted insertion-type heater is
self-regulating. See table 5 for crankcase heater
specifications. Crankcase heater is optional for 10HP12.
10HP CRANKCASE HEATER RATINGS
Unit
10HP18, 24 and 30
10HP36
10HP36–4, 42, 48 and 60
10HP36 (CDN)
TABLE 5
Rating (Watts)
19 watts
27 watts
40 watts
30 watts
DISCHARGED
Page 6
Page 7
5 – Compressor Cover (Figure 11)
A compressor cover
constructed of vinyl-faced
fiberglass is used on all
10HP18 through 10HP60
units. The cover provides an
acoustic barrier. The cover
slides over the compressor
and is held secure with
velcrot straps. Slits are
provided for installation
around the discharge and suction lines.
COMPRESSOR COVER
COVER
SLIT FOR DISCHARGE LINE
SLIT FOR
SUCTION
LINE
VELCROt
STRAPS
COMPRESSOR
FIGURE 11
C – Outdoor Fan Motor
All units use single–phase PSC fan motors which
require a run capacitor. Refer to tables on pages 1 and 2
for specifications of outdoor fans used in the 10HP
series. In all units, the outdoor fan is controlled by the
compressor contactor and defrost relay.
Two different mounting arrangements are used (fan
motor up and fan up) see figures 12 and 13.
OUTDOOR FAN MOTOR AND COMPRESSOR
ACCESS “FAN UP” UNITS (3.5 TONS AND LARGER)
LIFT FAN GUARD OFF AFTER REMOVING SIX SCREWS
Remove (6) screws
FAN
MOTOR
Screws
REMOVE SIX SCREWS
SECURING FAN GUARD.
REMOVE FAN GUARD
TO ACCESS FAN.
FIGURE 12
OUTDOOR FAN MOTOR AND COMPRESSOR
ACCESS “MOTOR UP” UNITS (3 TONS AND UNDER)
Remove six
screws
Screws
FAN GUARD
WIRING
REMOVE SIX SCREWS SECURING FAN GUARD.
REMOVE FAN GUARD/FAN ASSEMBLY.
FIGURE 13
SPIDER
MOTOR
FAN
RACEWAY
Access to the outdoor fan motor on all units is gained
by removing the six screws securing the fan guard.
See figures 12 and 13. The outdoor fan motor is
attached to the fan guard on “motor up” units and is
removed with the fan guard. See figure 13.
The reversing valve requires no
maintenance. It is not rebuildable. If the reversing
valve has failed, it must be replaced.
If replacement is necessary, access the reversing valve
by removing the control box. 10HP42 through 10HP60
series units have a filler panel that can also be removed
for reversing valve access. Refer to figure 14 .
10HP SERIES REVERSING VALVE ACCESS
(CONTROL BOX REMOVAL)
NOTE-UNIT ELECTRICAL COMPONENTS
AND PLUMBING HAVE BEEN DELETED
FOR CLARITY
1 – Turn off all power to unit and
remove control box cover. If rigid
conduit is used to route wiring
to outdoor unit, disconnect
power leads at contactor,
remove hardware attaching
conduit to control box and
move conduit out of the way.
DISCHARGE CAPACITORS.
Thermostat wiring can be left intact.
2 – Label and disconnect the three fan
motor leads from control box. Remove
unit top. Note-fan guard/fan/fan motor
is left intact.
3 – On 10HP42 thru 60 models remove panel. Do not disconnect plumbing.
4 – Remove four screws securing plate to control box.
5 – Disconnect and label compressor and crankcase leads. Pull leads into com-
pressor compartment. Disconnect reversing valve wiring harness from re-
versing valve coil.
6 – Remove four screws securing control box to outdoor coil. Remove control
box by lifting straight up and out of unit.
7 – Reverse procedures for reassembly.
FIGURE 14
III – REFRIGERANT SYSTEM
Refer to figures 15, 16 and 17 for refrigerant
DISTRIBUTOR
(TO OUTDOOR COIL)
TO SENSING
10HP LIQUID LINE COMPONENTS
EXPANSION
VALVE
EQUALIZER
LINE
BULB
REFRIGERANT
FLOW IN
HEATING
MODE
STRAINER
(TO INDOOR COIL)
FIGURE 15
PRESSURE TAP FITTING
WITH VALVE CORE
DEFROST
THERMOSTAT
(S6)
DRIER WITH
CHECK VALVE
REFRIGERANT
FLOW IN
COOLING
MODE
Page 7
Page 8
10HP COOLING CYCLE (SHOWING GAUGE MANIFOLD CONNECTIONS)
DEFROST THERMOSTAT
EXPANSION VALVE
FILTER / DRIER
WITH INTERNAL CHECK VALVE
SUCTION
HIGH
PRESSURE
MUFFLER
STRAINER
OUTDOOR
COIL
INTERNAL
COMPRESSOR
LIMIT
SUCTION
SERVICE
PORT
REVERSING
VAL VE
OUTDOOR UNIT
NOTE – ARROWS INDICATE DIRECTION OF
REFRIGERANT FLOW
INDOOR
UNIT
LIQUID
TO
R–22
DRUM
LINE
SERVICE
PORT
10HP HEATING CYCLE (SHOWING GAUGE MANIFOLD CONNECTIONS)
DEFROST THERMOSTAT
EXPANSION
VAL VE
FILTER / DRIER
WITH INTERNAL CHECK VALVE
SUCTION
PRESSURE
TO
R–22
DRUM
HIGH
LIQUID
LINE
SERVICE
PORT
THERMOMETER WELL
THERMOMETER
WELL
MUFFLER
COMPRESSOR
STRAINER
COMPRESSOR
SUCTION
MUFFLER
FIGURE 16
OUTDOOR
COIL
INTERNAL
COMPRESSOR
LIMIT
SUCTION
MUFFLER
FIGURE 17
10HP12
ONLY
ACCUMULATOR
10HP12, 48 AND
SUCTION
SERVICE
PORT
10HP12
ONLY
ACCUMULATOR
10HP12, 48 AND
60 ONLY
60 ONLY
VAPOR
LINE
VAL VE
EXPANSION
REVERSING
VAL VE
VAPOR
LINE
VAL VE
EXPANSION
VALVE OR RFCIII
CHECK
VAL VE
VALVE OR
RFCIII
INDOOR
COIL
OUTDOOR UNIT
NOTE – ARROWS INDICATE DIRECTION OF
REFRIGERANT FLOW
INDOOR
UNIT
CHECK
VAL VE
INDOOR
COIL
A – Service Valves
The liquid line and vapor line service valves and gauge
ports are accessible from outside of the unit. Full
service liquid and vapor line valves are used. See
figures 18 and 19. The service ports are used for leak
testing, evacuating, charging and checking charge.
1 – Liquid Line Service Valve
A full-service liquid line valve made by one of several
manufacturers may be used. All liquid line service
valves function the same way, differences are in
construction. Valves manufactured by Parker are
forged assemblies. Valves manufactured by Primore
are brazed together. Valves are not rebuildable. If a
valve has failed it must be replaced. The liquid line
service valve is illustrated in figure 18.
The valve is equipped with a service port. There is no
schrader valve installed in the liquid line service port. A
service port cap is supplied to seal off the port.
The liquid line service valve is a front and back seating
valve. When the valve is backseated the service port is
not pressurized. The service port cap can be removed
and gauge connections can be made.
CAUTION
The service port cap is used to seal the liquid line
service valve. Access to service port requires
backseating the service valve to isolate the
service port from the system. Failure to do so
will cause refrigerant leakage.
Page 8
Page 9
IMPORTANT
A schrader valve is not provided on the liquid line
service port. Valve must be backseated to turn off
pressure to service port.
LIQUID LINE SERVICE VALVE
STEM CAP
VALVE STEM
USE SERVICE
WRENCH
(PART #18P66,
54B64 or 12P95)
OUTLET
(TO INDOOR COIL)
TO LINE SET
KNIFE EDGE SEAL
VALVE
BACKSEATED
(FROM OUTDOOR COIL)
SERVICE PORT
CLOSED TO LINE SET
AND UNIT
(NO PRESSURE)
INLET
SERVICE PORT CAP
TO OUTDOOR UNIT
(COIL)
4 – When finished using port, backseat stem with
service wrench. Tighten firmly.
5 – Replace service port and stem cap. Tighten finger
tight, then tighten an additional 1/6 turn.
To Close Off Service Port:
1 – Using service wrench, backseat valve.
a – Turn stem counterclockwise.
b – Tighten firmly.
To Open Liquid Line Service Valve:
1 – Remove the stem cap with an adjustable wrench.
2 – Using service wrench, backseat valve.
a – Turn stem counterclockwise until backseated.
b – Tighten firmly.
3 – Replace stem cap, finger tighten then tighten an
additional 1/6 turn.
To Close Liquid Line Service Valve:
1 – Remove the stem cap with an adjustable wrench.
2 – Turn the stem in clockwise with a service wrench to
front seat the valve. Tighten firmly.
3 – Replace stem cap, finger tighten then tighten an
additional 1/6 turn.
2 – Vapor Line Service Valve
WARNING
KNIFE EDGE
SEAL
STEM CAP
VALVE STEM
USE SERVICE WRENCH
(PART #18P66)
TO LINE SET
VALVE FRONT
SEATED
SERVICE PORT
OPEN TO
LINE SET
AND CLOSED
TO UNIT
TO OUTDOOR
UNIT (COIL)
IMPORTANT
A schrader valve is not provided on the liquid line
service port. Valve must be backseated to turn off
pressure to service port.
FIGURE 18
To Access Service Port:
1 – Remove the stem cap. Use a service wrench
(part #18P66, 54B64 or 12P95) to make sure the
service valve is backseated.
2 – Remove service port cap and connect high pressure
gauge to service port.
3 – Using service wrench, open valve stem (one turn
clockwise) from backseated position.
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.
A full service non-backseating vapor line service valve
is used on all 10HP series units. Different manufacturers
of valves may be used. All vapor line service valves
function the same way, differences are in construction.
Valves manufactured by Parker are forged assemblies.
Valves manufactured by Primore and Aeroquip are
brazed together. Valves are not rebuildable. If a valve
has failed it must be replaced. The vapor line service
valve is illustrated in figure 19.
The 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.
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 tighten an additional
1/6 turn.
Page 9
Page 10
VAPOR LINE SERVICE VALVE (VALVE OPEN)
INSERT HEX WRENCH
HERE (PART #49A71 AND
SERVICE WRENCH)
INLET
(FROM INDOOR COIL)
SCHRADER VALVE
SNAP RING
KNIFE EDGE SEAL
STEM CAP
VAPOR LINE SERVICE VALVE (VALVE CLOSED)
KNIFE EDGE SEAL
(FROM INDOOR COIL)
INLET
SERVICE PORT
SNAP RING
HEX WRENCH HERE
(PART #49A71 AND
STEM
CAP
INSERT
SERVICE
WRENCH)
SERVICE PORT
CAP
SERVICE PORT
OUTLET
(TO COMPRESSOR)
FIGURE 19
To Open Vapor Line Service Valve:
1 – Remove stem cap with an adjustable wrench.
2 – Using service wrench and 5/16” hex head
extension (part #49A71) back the stem out
counterclockwise until the valve stem just touches
the retaining ring.
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.
3 – Replace stem cap tighten firmly. Tighten finger
tight, then tighten an additional 1/6 turn.
To Close Vapor Line Service Valve:
1 – Remove stem cap with an adjustable wrench.
TABLE 6
LINE SET SPECIFICATIONS
Condensing
Unit
Model No.
10HP12
10HP18
10HP24
10HP30
10HP36
10HP42
10HP48
10HP60
*Field Fabricate
**3/8” x 1/4” reducer furnished to adapt unit to 1/4 field fabricated line set.
*** 3/8” x 5/16” reducer furnished to adapt unit to 5/16” line set.
Line
Set
Model No.
*Not Available
L10–21–20
L10–21–25
L10–21–35
L10–21–50
L10–41–20
L10–41–30
L10–41–40
L10–41–50
L10–65–30
L10–65–40
L10–65–50
*Not Available
Length of
Vapor & Liq.
Lines (ft.)
20
25
35
50
20
30
40
50
30
40
50
Liquid
Line
(o.d. ft.)
**1/4
***5/16
***5/16
***5/16
***5/16
3/8 3/4
3/8
3/8
3/8
3/8 7/8
3/8
3/8
3/8 1–1/8
Vapor
Line
(o.d. ft.)
1/2
5/8
5/8
5/8
5/8
3/4
3/4
3/4
7/8
7/8
SERVICE PORT CAP
SCHRADER VALVE OPEN
TO LINE SET WHEN
VALVE IS CLOSED
(FRONT SEATED)
(TO COMPRESSOR)
(VALVE
FRONT SEATED)
OUTLET
2 – Using service wrench and 5/16” hex head
extension (part #49A71) turn stem in clockwise to
seat the valve. Tighten firmly.
3 – Replace stem cap. Tighten finger tight, then
tighten an additional 1/6 turn.
B – Plumbing
See figures 20 and 21 for unit refrigerant components.
Field refrigerant piping consists of liquid and vapor
lines from the outdoor unit (sweat connections). Use
Lennox L10 series line sets as shown in table 6 or field
fabricated refrigerant lines.
IV – CHARGING
IMPORTANT
Units manufactured before September 1, 1992
have a sufficient charge for a 25ft. line set. Units
manufactured after September 1, 1992 have
sufficient charge for a 20ft. line set. Refer to unit
nameplate for factory supplied charge.
Unit charge is based on a matching indoor coil and
outdoor coil with a 20 foot (6096 mm) line set. For varying
lengths of line set, refer to table 7.
TABLE 7
Liquid Line
Set Diameter
1/4 in. (6 mm)
5/16 in. (8mm)
3/8 in. (10 mm)
*If line set is greater than 20 ft. (6.10m) add this amount. If line set is less
than 20 ft. (6.10m) subtract this amount
Ounce per 5 foot (ml per mm)
adjust from 20 ft. (6096mm)*
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)
Page 10
Page 11
10HP12 REFRIGERATION COMPONENTS
SUCTION
MUFFLER
DISTRIBUTOR
SUCTION LINE
SERVICE
VALVES
LIQUID LINE
SERVICE PORT
DEFROST
SWITCH S6
FILTER/DRIER
W/INTERNAL
CHECK VALVE
EXPANSION VALVE
STRAINER
LIQUID LINE FROM INDOOR COIL
TO OUTDOOR COIL
REVERSING VALVE
VAPOR LINE FROM
INDOOR COIL
FIGURE 20
10HP18 AND LARGER TYPICAL REFRIGERATION COMPONENTS
ACCUMULATOR
10HP42, 48 AND 60 ONLY
DISTRIBUTOR
COMPRESSOR
SUCTION LINE
ACCUMULATOR
SENSING
BULB
DISCHARGE LINE
SERVICE PORT
MUFFLER
ROTARY COMPRESSOR
SENSING BULB
TO
OUTDOOR COIL
REVERSING
VALVE
SERVICE
VALVES
A – Pumping Down System
CAUTION
Deep vacuum operation (operating compressor
below 0 psig) can cause internal fusite arcing
resulting in a damaged or failed compressor. This
type of damage will result in denial of warranty
claim.
LIQUID LINE
SERVICE PORT
DEFROST
SWITCH S6
CHECK VALVE
FIGURE 21
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 in cooling mode.
4– Monitor suction gauge. Stop unit when 0 psig. is
5– Front seat (close) suction line valve.
FILTER/DRIER
W/INTERNAL
reached.
DISCHARGE LINE
SERVICE PORT
VAPOR LINE FROM
INDOOR COIL
MUFFLER
STRAINER
EXPANSION VALVE
LIQUID LINE FROM
INDOOR COIL
Page 11
Page 12
B – 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.
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
The compressor should never be used to evacuate
a refrigeration or air conditioning system.
4– Release nitrogen pressure from the system,
correct any leaks and recheck.
CAUTION
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.
NOTE-If electronic leak detector is used, add a trace of
refrigerant to the nitrogen for detection by the leak
detector.
D – Charging
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 evacuating system 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.
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
29.7 inches (754mm) mercury (5mm absolute
pressure) 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.
C – Leak Testing (To Be Done Only After
Pump Down)
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 /indoor coil to 150 psig (1034 kPa).
3– Check lines and connections for leaks.
Charging must be done in the cooling mode. If 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 and in table 8.
Separate discharge and vapor line service ports are
provided outside the unit for connection of gauge
manifold during charging procedure as well as a
suction line service port.
TABLE 8
10HP REFRIGERANT CHARGE*
Unit
10HP12
10HP18
10HP24
10HP30
10HP36
10HP36-4
10HP36 [CAN]
10HP42
10HP48
10HP60
Refrigerant Charge R–22
5 lbs. 3 oz.
5 lbs. 6 oz.
6 lbs. 2 oz.
7 lbs. 3 oz.
7 lbs. 5 oz.
7 lbs. 14 oz.
7 lbs. 7 oz.
8 lbs. 3 oz.
9 lbs. 6 oz.
12 lbs. 13 oz.
If weighing facilities are not available or if unit is just
low on charge, the following procedure applies. RFC
and TXV systems use different charging methods.
1 – Expansion Valve Systems
The following procedures are intended as a general
guide for use with expansion valve systems only. For
best results, indoor temperature should be between 70 °F
and 80 °F. 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.
Page 12
Page 13
IMPORTANT
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 and a pressure gauge with accuracy of +5 PSIG.
BLOCKING OUTDOOR COIL
Block outdoor coil one side at
a time with cardboard or
plastic sheets until proper
testing pressures are reached.
CARDBOARD OR
PLASTIC SHEET
FIGURE 22
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 a few degrees warmer than the outdoor air
temperature. Table 9 shows how many
degrees warmer the liquid line temperature
should be.
Add refrigerant to make the liquid line
temperature cooler.
Recover refrigerant to make the liquid line
temperature warmer.
TABLE 9
APPROACH METHOD – EXPANSION VALVE SYSTEMS
AMBIENT TEMPERATURE OF 60 _F (16 _C) OR ABOVE
Model
10HP12
10HP18
10HP24
10HP30
10HP36
10HP36 (CAN)
10HP42
10HP48
10HP60
Liquid Line °F Warmer Than Outside
(Ambient) Temperature
6
5
7
14
14
11
11
11
7
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 a few degrees warmer than the
liquid line temperature.
5 – Place thermometer in well and read liquid line
temperature. Table 10 shows how much
warmer the condensing temperature should be.
Add refrigerant to make the liquid line
temperature cooler.
Recover refrigerant to make the liquid line
temperature warmer.
TABLE 10
SUBCOOLING METHOD – EXPANSION VALVE SYSTEMS
AMBIENT TEMPERATURE BELOW 60 _F (16 _C)
Model
10HP12
10HP18
10HP24
10HP30
10HP36
10HP36 (CAN)
10HP42
10HP48
10HP60
Condensing Temp°F Warmer Than
Liquid Line
2
4 +
2
9 +
13 +
2
9 + 2
9 + 2
13 +
2
8 +
2
2
6 +
7 +
2
6 – When unit is properly charged liquid line
pressures should approximate those given in
table 11.
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. Block equal
sections of air intake panels as shown in figure 22,
moving obstructions sideways until liquid pressures
in the 200-250 psig range are reached.
IMPORTANT
Use table 11 as a general guide for performing
maintenance checks. Table 11 is not a procedure for
charging the system. Minor variations in pressures
may be expected due to differences in installations.
Significant deviations may mean the system is not
properly charged or that a problem exists with some
component in the system. Used prudently, table 11
could serve as a useful service guide.
Page 13
Page 14
10HP NORMAL OPERATING PRESSURES (COOLING MODE)
OUTDOOR COIL
ENTERING AIR
TEMPERATURE
65° F (TXV)
° F (TXV)
75
° F (TXV)
85
95
° F (TXV)
° F (TXV)
105
° F (RFC III)
65
75
° F (RFC III)
° F (RFC III)
85
95
° F (RFC III)
° F (RFC III)
105
*For an approved match-up the 10HP60 must be used with a TXV.
10HP12 10HP24 10HP30 10HP36
LIQ.
10
+
PSIG
137
155
182
210
240
130
155
175
210
240
SUC.
+
10
PSIG
78
79
80
82
83
59
67
75
82
87
10HP18
LIQ.
10
+
PSIG
145
165
195
225
255
150
170
195
230
260
SUC.
+ 10
PSIG
72
73
74
77
79
61
68
75
81
85
SUC.
LIQ.
10
+ 10
+
PSIG PSIG
160
74
185
76
215
78
245
80
275
84
150
60
175
67
205
73
240
78
280
81
SUC.
LIQ.
10
+ 10
+
PSIG PSIG
170
75
195
77
225
78
255
80
290
82
165
62
190
69
220
74
255
80
285 84
2 – RFCIII Systems
The system should not be charged at ambients below
60 _F (15_C). If charging below 60 _F (15_C) is required,
the recommended method of charging is to weigh the
refrigerant into the unit according to the total amount
shown on the unit nameplate and in table 8. For line sets
varying from 20 feet, refer to table 7 for refrigerant charge
adjustment. If ambient temperature is above 60 _F (15_C)
use the subcoooling method outlined below.
SUBCOOLING METHOD (RFCIII SYSTEMS)
(Ambient Temperature Above 60_F [16_C] )
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 a few degrees warmer than the
liquid line temperature.
SUBCOOLING METHOD––RFCIII Systems*
Condensing Temp°F Warmer
TABLE 11
Outdoor
Unit
10HP12
10HP18
10HP24
10HP30
10HP36 CB/CBH19–41 17 15 14 11 8 5
10HP36 (CAN) CB/CBH19–41
10HP42
*Approved matchups only
Indoor
Unit
CB/CBH19–21
CB/CBH19–21
CB/CBH19–26
CB/CBH19–31
CB/CBH19–41
CB19–5110HP48
5 – Place thermometer in well and read liquid line
temperature. Table 12 shows how much
warmer the condensing temperature should be.
Than Liquid Line At Various
65_F75_F85_F95_ F 105_F 115_F
5
13
12
12
18 16 15 12 9 6
11
11
5
13
12
12
10
10
Ambients
4
1
13
12
11
9
10
8
7
6
8
7
0
0
6
4
7
5
6
4
4
2
5
2
LIQ.
SUC.
+ 10
+ 10
PSIG PSIG
175
75
200
76
227
77
260
79
295
81
170
61
205
68
230
73
265
79
305
82
10HP36 (CAN)
LIQ.
SUC.
+
10
+ 10
PSIG PSIG
175
76
200
77
230
78
260
79
295
81
160
62
190
68
225
70
255
77
385
81
10HP42 10HP48 10HP60
SUC.
LIQ.
10
+ 10
+
PSIG PSIG
160
185
215
245
280
155
180
210
240
275
72
74
76
78
80
61
63
68
73
76
SUC.
LIQ.
10
+ 10
+
PSIG PSIG
165
185
210
240
275
155
185
210
245
275
72
73
76
78
80
63
64
69
74
78
Add refrigerant to make the liquid line
temperature cooler.
Recover refrigerant to make the liquid line
temperature warmer.
6 – When unit is properly charged liquid line
pressures should approximate table 11.
E – Oil Charge
Refer to table 4 on page 6 for factory oil charge.
V – MAINTENANCE
At the beginning of each heating or cooling season, the
system should be cleaned as follows:
A – Outdoor Unit
1 – Clean and inspect outdoor coil. (Coil may be
flushed with a water hose).
2 – Outdoor fan motor is prelubricated and sealed.
No further lubrication is required.
3 – Visually inspect all connecting lines, joints
and coils for evidence of oil leaks.
NOTE-If insufficient heating or cooling occurs, unit
should be gauged and refrigerant charge checked.
B – Indoor Coil
1 – Clean coil if necessary.
2 – Check connecting lines, joints and coil for
evidence of oil leaks.
3 – Check condensate line and clean if necessary.
C – Indoor Unit
1 – Clean or change filters.
2 – Check blower motor for debris. Blower motors
are prelubricated and sealed. No further
lubrication required.
3 – Adjust blower speed for cooling. Static
pressure drop over the coil should be checked
to determine the correct blower CFM. Refer to
Lennox Engineering Handbook for Static
Pressure and CFM tables.
4 – Check all wiring for loose connections.
5 – Check for correct voltage at unit.
6 – Check amp–draw on blower motor.
Unit nameplate_________Actual_________.
LIQ.
SUC.
10
+
PSIG
150
175
200
235
265
10
+
PSIG
73
75
76
78
80
*
*
**
*
*
**
**
Page 14
Page 15
VI – WIRING DIAGRAM AND SEQUENCE OF OPERATION
10HP OPERATING SEQUENCE
14
15
22
21
28
19
18
26
25
24
20
2
17
1
13
16
5
8
10
4
12
7
3
27
23
6
11
9
A–10HP Operation Sequence
This is the sequence of operation for 10HP 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 – Cooling demand initiates at Y1 in the thermostat. Internal thermostat
wiring energizes terminal O energizing the reversing valve L1.
2 – Compressor contactor K1 is energized.
3 – K1-1 N.O. closes energizing compressor (B1) and outdoor fan motor
(B1). Compressor (B1) and outdoor fan motor (B4) begin immediate
operation.
END OF COOLING DEMAND:
4 – Cooling demand is satisfied. Terminal Y1 is de-energized.
5 – Terminal O and reversing valve L1 are 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.
FIRST STAGE HEAT:
8 – Heating demand initiates at W1 in the thermostat. Compressor
contactor K1 is energized.
9 – K1-1 N.O. closes energizing compressor and outdoor fan mo-
tor. Compressor (B1) and outdoor fan motor (B4) begin im-
mediate operation.
END OF FIRST STAGE HEAT:
10 – Heating demand is satisfied. Terminal W1 is de-energized.
11 – Compressor contactor K1 is de-energized.
12 – K1-1 opens and compressor (B1) and outdoor fan motor (B4) are de-
energized and stop immediately.
AUXILIARY HEAT (SECOND STAGE):
13 – Additional heating demand initites at W3 in the thermostat. Outdoor
unit remains running. W1 of indoor unit terminal strip TB1 is energized
initiating first stage heat from indoor unit.
14 – If outdoor temperature is below the balance point, N.O. low ambient
cut in thermostat S23 will close.
15 – When S23 is closed, W2 of indoor unit terminal strip TB1 is energized
initiating second stage heat from indoor unit.
END OF AUXILIARY HEAT (SECOND STAGE):
16 – Heating demand is satisfied. Terminal W3 is de-energized. Indoor unit
heating operation stops and outdoor unit continues operation.
EMERGENCY HEAT:
17 – Emergency heat mode is set at the thermostat. Outdoor unit will not
be operational in this mode. Terminal E2 is energized in the thermostat. Emergency heat relay K26 is energized.
18 – N.O. K26-1 closes energizing W1 and W2 on terminal strip TB1 of in-
door unit. Indoor unit operates in second stage heat mode.
DEFROST MODE:
19 – During heating operation when outdoor coil temperature drops be-
low 35_ +
4_ F Defrost Switch (thermostat) S6 closes.
20 – Defrost control CMC1 begins timing. If defrost thermostat (S6) re-
mains closed at the end of the 30,60 or 90 minute period, defrost relay
K4 energizes and defrost begins.
21 – N.O. K4-3 closes energizing the reversing valve.
22 – N.O. K4-1 closes energizing W1 on TB1 terminal strip of indoor unit.
Indoor unit operates in the first stage heat mode.
23 – N.C. K4-2 opens and outdoor fan motor B4 stops.
24 – Defrost continues 14 +
1 minutes or until thermostat switch (S6)
opens. When defrost thermostat opens defrost control CMC1 loses
power and resets.
25 – Defrost relay K4 is de-energized.
26 – K4-1 opens and W1 on terminal strip TB1 of indoor unit is de-ener-
gized.
27 – K4-2 closes and the outdoor fan begins operation.
28 – K4-3 opens de-energizing the reversing valve.
Page 15
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10HP WITH ELECTROMECHANICAL THERMOSTAT
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