Lennox HP27?024, HP27-030, HP27-036, HP27-042 Unit Information
HP27
Netfacearea
Coil
Fan
p
Outdoor Coil
Corp. 9621−L10
Service Literature
HP27 SERIES UNITS
The HP27 is a high efficiency residential split−system heat
pump which features a scroll compressor. It operates
much like a standard heat pump, but the scroll compressor
is unique in the way that it compresses refrigerant. Several
models are available in sizes ranging from 2 through 3-1/2
tons. The series uses expansion valves in the outdoor unit
and in the indoor unit.
This manual is divided into sections which discuss the major components, refrigerant system and charging procedures, maintenance and operation sequences. All specifications in this manual are subject to change.
Model No. HP27−024 HP27−030 HP27−036 HP27−042
Netfacearea
sq. ft. (m2)
Condenser
Condenser
Fan
Refrigerant furnished (HCFC-22) 12 lbs. 5 oz. (5.6 kg) 11 lbs. 5 oz. (5.1 kg) 11 lbs. 13 oz. (5.3 kg) 12 lbs. 12 oz. (5.8 kg)
Liquid line conn. o.d. in. (mm) (sweat) 3/8 (9.5) 3/8 (9.5) 3/8 (9.5) 3/8 (9.5)
Vapor line conn. o.d. in. (mm) (sweat) 3/4 (19) 3/4 (19) 7/8 (22.2) 7/8 (22.2)
Shipping wt. lbs. (kg) 1 package 268 (122) 271 (123) 328 (149) 328 (149)
Refrigerant charge sufficient for 15 ft. (4.5 m) length of refrigerant lines.
Line voltage data 208/230v 60hz−1ph
Compressor
Outdoor Coil
Fan Motor
Rec. max. fuse or circuit breaker size (amps) 20 25 30 40
Minimum circuit ampacity 13.8 16.2 17.8 23.4
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.
Tubediameter in. (mm) 5/16 (7.9) 5/16 (7.9) 5/16 (7.9) 5/16 (7.9)
No. of rows 2 2 2 2
Fins per inch (m) 22 (866) 22 (866) 22 (866) 22 (866)
Diameter in. (mm) No. of blades 24( 610) − 3 24( 610) − 3 24( 610) − 3 24( 610) − 3
Motor hp (W) 1/10 (75) 1/10 (75) 1/10 (75) 1/10 (75)
Cfm (L/s) 2800 (1320) 2800 (1320) 2800 (1320) 2800 (1320)
Rpm 825 825 825 825
Watts 165 165 170 170
Model No. HP27−024 HP27−030 HP27−036 HP27−042
Rated load amps 10.26 12.18 13.46 18.0
Power factor 0.96 0.96 0.96 0.97
Locked rotor amps 56 61 73 104
Full load amps 0.9 0.9 0.9 0.9
Locked rotor amps 1.6 1.6 1.6 1.6
Outer Coil 21.77 (2.02) 21.77 (2.02) 24.06 (2.24) 24.06 (2.24)
Inner Coil 21.11 (1.96) 21.11 (1.96) 23.33 (2.17) 23.33 (2.17)
Revised 08−2004
SPECIFICATIONS
ELECTRICAL DATA
Page 1
© 1997 Lennox Industries Inc.
Litho U.S.A.
DISCHARGE
SUCTION
SCROLL COMPRESSOR
CROSS−SECTION OF SCROLLS
DISCHARGE
DISCHARGE
PRESSURE
SCROLL FORM
FIGURE 2
STATIONARY SCROLL
SUCTION
FIGURE 1
I−APPLICATION
All major components (indoor blower/coils) must be
matched according to Lennox recommendations for the
compressor to be covered under warranty. Refer to the
Engineering Handbook for approved system matchups. A
misapplied system will cause erratic operation and can result in early compressor failure.
II−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 1. The scrolls are located in
the top of the compressor can and the motor is located in
the bottom of the compressor can. The oil level is immediately below the motor.
The scroll is a simple compression concept centered
around the unique spiral shape of the scroll and its inherent properties. Figure 2 shows the basic scroll form. Two
identical scrolls are mated together forming concentric
spiral shapes (figure 3). One scroll remains stationary,
while the other is allowed to "orbit" (figure 4). Note that the
orbiting scroll does not rotate or turn but merely orbits the
stationary scroll.
NOTE − The head of a scroll compressor may be hot since
it is in constant contact with discharge gas.
TIPS SEALED BY
DISCHARGE PRESSURE
ORBITING SCROLL
FIGURE 3
The counterclockwise orbiting scroll draws gas into the outer crescent shaped gas pocket created by the two scrolls
(figure 4 − 1). The centrifugal action of the orbiting scroll
seals off the flanks of the scrolls (figure 4 − 2). As the orbiting motion continues, the gas is forced toward the center of
the scroll and the gas pocket becomes compressed (figure
4 − 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 1). The discharge pressure forcing down on the top scroll helps seal off the upper
and lower edges (tips) of the scrolls (figure 3). 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. Continued
slugging of liquid will cause damage to the scroll and replacement will be necessary. 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.
Page 2
SUCTION
POCKET
HOW A SCROLL WORKS
SUCTION
MOVEMENT OF ORBIT
ORBITING
SCROLL
SUCTION
INTERMEDIATE
PRESSURE
GAS
CRESCENT
SHAPED GAS
POCKET
12
FLANKS
STATIONARY SCROLL
SUCTION
SEALED BY
CENTRIFUGAL
FORCE
SUCTION
34
HIGH
PRESSURE
GAS
FIGURE 4
III−UNIT COMPONENTS
A−Transformer
The contactor, reversing valve, time delay, and defrost timer are all powered by 24VAC supplied by the indoor unit.
All other controls in the outdoor unit are powered by line
voltage. Refer to unit wiring diagram. The HP27 is not
equipped with an internal line voltage to 24V transformer.
B−Terminal Strip
All HP27s are equipped with a low voltage terminal strip
located in the unit control box for making thermostat wiring
connections (refer to figure 6).
C−Compressor
Table 1 shows the specifications of compressors (B1)
used in HP27 series units.
TABLE 1
Unit Phase LRA RLA
*Shipped with conventional white oil (Sontex 200LT). 3GS oil may be
used if additional oil is required.
Vac
208/230HP27−024 56 10.3 38
208/230
208/230
208/230
1
1HP27−030
61 42
1HP27−036
73
1HP27−042
12.2
13.5
18.0104
Oil
fl.oz.
42
42
DISCHARGE
POCKET
COMPRESSOR TERMINAL BOX
COMPRESSOR
TERMINALS
C
S
R
WARNING
COMPRESSOR MUST BE GROUNDED. DO
NOT OPERATE WITHOUT PROTECTIVE COVER
OVER TERMINALS. DISCONNECT ALL POWER
BEFORE REMOVING PROTECTIVE COVER.
DISCHARGE CAPACITORS BEFORE SERVICING UNIT. COMPRESSOR WIRING DIAGRAM IS FURNISHED INSIDE COMPRESSOR
TERMINAL BOX COVER. FAILURE TO FOLLOW
THESE PRECAUTIONS COULD CAUSE ELECTRICAL SHOCK RESULTING IN INJURY OR
DEATH.
FIGURE 5
Page 3
DUAL CAPACITOR
TXV
SENSING BULB −036,
−042 ONLY
HIGH PRESSURE
SWITCH
BIFLOW FILTER/DRIER
EXPANSION VALVE
WITH
INTERNAL CHECK
VALV E
DEFROST
THERMOSTAT
DISTRIBUTOR
ACCUMULATOR
HP27 UNIT COMPONENTS
DEFROST CONTROL/TIMED−OFF CONTROL
TXV
SENSING BULB
−024, −030 ONLY
THERMOMETER WELL
MUFFLER
CONTACTOR
GROUND LUG
TERMINAL STRIP
SUCTION
GAUGE
PORT
VAPOR LINE
SERVICE VALVE
AND GAUGE
PORT
LIQUID LINE
SERVICE VALVE
AND GAUGE
PORT
REVERSING
VALV E
AND SOLENOID
D−High Pressure Switch
An automatic reset high pressure switch (S4) located in the
liquid line of the compressor shuts off the compressor when
liquid line pressure rises above the factory setting. The switch
is normally closed and is permanently adjusted to trip (open)
at 410 + 10 psi. The switch closes at 210 + 10 psi. See figure 6
for switch location.
E−Contactor
The compressor is energized by a contactor (K1) located
in the control box. Units will use single−pole or double−pole
contactors. See wiring diagrams for specific unit. The contactor is energized by indoor thermostat terminal Y 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 6
F−Condenser Fan Motor
See page 1 for specifications for all condenser fan motors
(B4) used. See figure 7 if condenser fan motor replacement is necessary. In all units, the condenser fan motor is
controlled by the compressor contactor and is de−energized when the defrost relay is energized.
"A" SEE TABLE 2
Condenser fan
and motor
FAN GUARD
Wiring
Drip loop
FIGURE 7
TABLE 2
UNIT "A" DIM. TOLERANCE
HP27−024, −030 1 1/16" + 1/8"
HP27−036, −042 1 3/16" + 1/8"
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).
G−Accumulator
The accumulator is located on the liquid line (see figure 6.)
The accumulator retains liquid and releases mostly vapor
to the compressor. This ensures that the liquid refrigerant
will not enter and damage the compressor.
Page 4
H−Service Light Thermostat HP27
HP27−1 through −7 units are equipped with a service light
thermostat (S54) located on the compressor discharge
line. The switch is electrically connected to the service
light in the indoor thermostat. The service light, when lit,
indicates the compressor is not running. The service light
is powered from W1 (2nd stage heat) terminal of the indoor
thermostat. The service light thermostat will close when
the discharge line falls below 110 + 5F, indicating a problem in the system. The service light thermostat opens and
the service light goes off when discharge line reaches 130
+ 5F indicating the compressor is running.
I−Ambient Compensating Thermistor
HP27−1 through −7 units have an ambient compensating
thermistor (RT3) mounted on the outdoor fan wiring harness. The thermistor is an NTC thermistor (negative temperature coefficient − increase in temperature equals decrease in resistance) (see figure 8). The device is connected in series with the heat anticipation resistor inside the
indoor thermostat. This feature helps to prevent abnormal
droop caused by the anticipation resistors. As outdoor temperature increases, the resistance across the thermistor
drops. As the resistance across the thermistor drops, the
current through the heat anticipation resistor increases.
Therefore, heat anticipation increases as outdoor temperature decreases. Resistance at 77F = 260 ohms + 5%; at
100F = 150 ohms; at 32F = 861 ohms.
TABLE 3
HP27 DUAL CAPACITOR RATING
UNITS FAN MFD HERM MFD VAC
HP27−024 4 40 370
HP27−030 4 40 370
HP27−036 4 45 370
HP27−042 4 55 370
K−Reversing Valve and Solenoid
A refrigerant reversing valve (L1) with electromechanical
solenoid is used to reverse refrigerant flow during unit operation. The reversing valve is energized during cooling
demand and during defrost.
L−Defrost System HP27−1, −2, −3 and −5 units
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.
OUTDOOR FAN, BRACKET AND
AMBIENT COMPENSATING
THERMISTOR
OUTDOOR FAN
FAN MOTOR
BRACKET
FIGURE 8
J−Dual Capacitor
The compressor and fan in the HP27 series units use permanent split capacitor motors. A single dual capacitor
(C12) is used for both the fan motor and the compressor
(see unit wiring diagram). The fan side of the capacitor
and the compressor side of the capacitor have different
mfd ratings. The capacitor is located inside the unit control
box (see figure 6). Table 3 shows the ratings of the dual capacitor.
The defrost system includes two components: a defrost
thermostat (S6) and a defrost control.
Defrost Thermostat
The defrost thermostat is mounted on the liquid line between the check/expansion valve and the distributor. When
defrost thermostat senses 35F (2C) 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 70F (21C).
Defrost Control
The defrost control board has the combined functions
of a time/temperature defrost control, defrost relay,
time delay, diagnostic LEDs and field connection terminal strip. See figure 9.
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. If the defrost thermostat
remains closed when the accumulated compressor run
time ends, the defrost relay is energized and defrost begins.
Page 5
Defrost Control Timing Pins
Each timing pin selection provides a different accumulated compressor run 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, 60
or 90 minutes. See figure 9. The defrost period is a maximum of 14 minutes and cannot be adjusted. If no timing
is selected, the control defaults to 90 minutes.
DEFROST CONTROL BOARD
NOTE − COMPONENT LOCATIONS WILL VARY
WITH BOARD MANUFACTURER
PRESSURE SWITCH
SAFETY CIRCUIT
CONNECTIONS
DIAGNOSTIC
LEDs
AMBIENT
THERMISTOR
CONNECTION
SERVICE LIGHT
CONNECTION
NOTE− There is an internal jumper between
inside PS1 and PS2 terminals.
FIGURE 9
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. In order to test defrost cycle,
defrost thermostat must be closed or jumpered. Once defrost is initiated, remove jumper immediately. Failure to remove jumper will reduce defrost cycle to seconds.
DEFROST
INTERVAL
TIMING PINS
24V TERMINAL
STRIP
CONNECTIONS
Time-Delay
A 5-minute timed-off delay protects the compressor from
short-cycling when there is an interruption in power to the
unit or when a pressure switch resets.
Pressure Switch Safety Circuits
The defrost control incorporates a safety circuit that allows
the application of an additional pressure switch. The unit’s
high pressure switch (S4) is factory-wired into this circuit.
See figure 9. PS1 and PS2 terminals are wired in series
with a jumper internal to the control board. This feature is
available on all units.
During one demand cycle, the defrost control will lock out
the unit on the third instance that the unit goes off on any
auto−reset pressure switch wired to this circuit. In addition,
the diagnostic LEDs will indicate a locked out pressure
switch after the third occurrence of an open pressure
switch. See table 4. The unit will remain locked out until 24
volt power is broken to terminal R" on the defrost board
and then remade.
The PS2 safety circuit terminals are connected to the compressor thermostat. An optional loss of charge switch may
be field-installed by connecting it in series with the other
switches. See unit wiring diagram.
Diagnostic LEDs
The defrost board uses two LEDs for diagnostics. The
LEDs flash a specific sequence according to the condition.
TABLE 4
DEFROST CONTROL BOARD DIAGNOSTIC LED
MODE LED 1 LED 2
Normal Operation/
Power to board
Time Delay
To Protect Compressor
Pressure Switch Open Off On
Pressure Switch Lockout On Off
Board Malfunction On On
Flash together with
LED 2
Alternating Flashes
with LED 2
Flash together with
LED 1
Alternating Flashes
with LED 1
Ambient Thermistor & Service Light Connection
The defrost control board provides terminal connections
for the ambient thermistor and a service light. The thermistor compensates for changes in ambient temperature
which might cause thermostat droop. The service light
thermostat provides a signal which activates the room
thermostat service light during periods of inefficient operation.
Page 6
M−Defrost System HP27−4 and −6 ONLY
HP27−4 and −6 units are equipped with a demand defrost
system. The self−calibrating defrost control board includes
defrost relays, sensors (two) which monitor coil and out-
door ambient temperatures, a timed−off control, protection
circuits (two), a 3−strike lockout feature, a test mode jump-
er and a terminal strip. The demand defrost control board
initiates a defrost cycle based on temperature differential
and compressor run time. This type of system allows
greater frost accumulation on the outdoor coil and initiates
fewer defrost cycles than the time/temperature defrost
system. The defrost board is shown in figure 10.
Temperature Sensors
The demand defrost control board includes two perma-
nently attached sensors which monitor coil and outdoor
ambient temperatures. The coil temperature sensor is
equipped with a spring clip to allow proper positioning on
the outdoor coil. These sensors must not be detached
from the control board and must be replaced as part of the
control board. Do not attempt to cut or splice the tempera-
ture sensor wires. See figure 11 for ambient and coil tem-
perature sensor location.
Timed−Off Control
The control board includes a 5−minute timed−off delay
which protects the compressor from short cycling. The
5−minute delay is initiated at the end of a compressor
cycle, any time a system protection switch is reset, or if the
Y1 circuit is interrupted for more than two continuous line
cycles.
If a system protection switch opens while the Y1 OUT" circuit is energized, the timed−off control will initiate a 5−minute delay when the pressure switch closes.
The timed−off control run times can be bypassed by
shorting the TEST" pins.
Protection Circuits
The control board includes two protection circuits.
The unit high pressure switch is factory−wired to the HI −
PS terminals. The circuit through Y1" (input and Y1
OUT") is completed through the high pressure switch.
When the high pressure switch opens, the control board
de−energizes the compressor and the 3−strike lockout
counter registers one strike. If, for any reason, the high
pressure switch is removed, a jumper must be applied
across the HI − PS terminals to complete the circuit.
The second protection circuit is not used in this application
A jumper must be applied across the LO − PS terminals
to ensure proper control board operation.
Inputs (24V Terminal Strip Connections)
Y1 Thermostat input, controls unit operation
O Thermostat input, reversing valve
R 24VAC power
C 24VAC common
W1 24VAC input/output from indoor thermostat to indoor unit
L Service light thermostat
Ambient sensor (connection for Room Thermostat with
T
ambient compensation)
(1/4" Quick Connect Terminal Factory Connections)
HI−PS Pressure switch / system fault sensor
LO−PS Pressure switch / system fault sensor
Y1 Out Compressor contactor
O Out Reversing valve
FAN Condenser fan
W/L/C Service light thermostat
T/T Ambient sensor
Defrost Control Board
FAN
CC
Y1−OUT
Y
HI−PS
LO−PS
RV
O−OUT
C
LED1 LED2
100
AMB
90
80
70
PRESS
TEST
COIL
PS2
AUX
PS1
CUR
FAN
W1
C
L
T
DIS
IND
CLT
R
W1
O
Y1
FIGURE 10
Page 7
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