Lennox HP29-090 User manual

11/00
*2P1100*
504,342M
*P504342M*
Page 1
INSTALLATION
INSTRUCTIONS
HP29-090 (7.5 TON)
HP29-120 (10 TON)
HEAT PUMPS
504,342M
11/2000
See unit nameplate or manu acturer and address.
2000
Shipping & Packing Li t
1 - Assembled heat pump unit
Check the unit or shipping damage. I you ind any damĆ
age, immediately contact the last carrier.
General Information
These instructions are intended as a general guide and do
not supersede national or local codes in any way. Consult
authorities having jurisdiction installation.
IMPORTANT
Improper in tallation, adju tment, alteration, ervice
or maintenance can cau e property damage, per onĆ
al injury or lo of life. In tallation and ervice mu t
be performed by a qualified in taller or ervice
agency.
Table of Content
Shipping & Packing List 1. . . . . . . . . . . . . . . . . . . . . . .
General In ormation 1. . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Arrangement 3. . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Unit 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rigging the Unit or Li ting 7. . . . . . . . . . . . . . . . . . . . .
Electrical 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Plumbing 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Valves 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak Testing 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Evacuation & Dehydration 17. . . . . . . . . . . . . . . . . . . .
Start-Up 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Charging 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Operation 19. . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMPORTANT
The Clean Air Act of 1990 ban the intentional ventĆ
ing of refrigerant (CFC' and HCFC' ) a of July 1,
1992. Approved method of recovery, recycling or
reclaiming mu t be followed. Fine and/or incarceraĆ
tion may be levied for noncompliance.
CAUTION
A with any mechanical equipment, per onal injury
can re ult from contact with harp heet metal
edge . Be careful when you handle thi equipment.
RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE
HP29-090 HP29-120
Litho U.S.A.

Page 2
HP29-090 Serie Dimen ion - inche (mm)
CORNER WEIGHT
Model No
AA BB CC DD
Model No. lb . kg lb . kg lb . kg lb . kg
HP29-090 121 55 146 66 130 59 109 49
CENTER OF GRAVITY
Model No
EE FF
Model No. inch mm inch mm
HP29-090 22-1/2 572 19 483
SERVICE VIEW
OUTDOOR COIL
TOP VIEW
OUTDOOR COIL
OUTDOOR FAN
AND GUARD
COMPRESSOR
INLET
AIR
INLET
AIR
INLET
AIR
AA BB
CCDD
CENTER OF
GRAVITY
EE
FF
COMPRESSOR
3Ć1/4
(83)
34 (864)
CONTROL
BOX
ACCESS
OPTIONAL 115 VOLT OUTLET
(Factory In talled In ide Unit)
SIDE VIEW
LIFTING HOLES
(For Rigging)
FORKLIFT SLOTS
(Both Side )
ELECTRICAL INLETS
(Either Side)
LIQUID LINE
(Either Side)
2Ć1/4 (57)
48 (1219)
DISCHARGE AIR
CONTROL BOX
15Ć1/2
(394)
OPTIONAL HAIL GUARD
(Field In talled All Coil Side )
49Ć3/4 (1264) 35Ć3/4 (908)
OPTIONAL DISCONNECT
(Factory In talled)
BASE BASE
6Ć1/2
(165)
VAPOR LINE
(Either Side)
OPTIONAL HAIL GUARD
(Field In talled All Coil Side )
46-1/2
(1181)
43-1/4
(1099)
11-1/2
(292)
1-1/4
(32)

Page 3
HP29-120 Serie Dimen ion - inche (mm)
CORNER WEIGHT
Model No
AA BB CC DD
Model No. lb . kg lb . kg lb . kg lb . kg
HP29-120 130 59 183 83 183 83 130 59
CENTER OF GRAVITY
Model No
EE FF
Model No. inch mm inch mm
HP29-120 25 635 17-3/4 451
SIDE VIEW
TOP VIEW
58Ć5/8
(1489)
OUTDOOR COIL
OUTDOOR COIL
OUTDOOR FANS AND
GUARDS (2)
CONTROL
BOX
LIFTING HOLES
(For Rigging)
FORKLIFT SLOTS
(Both Side )
DISCHARGE AIR
INLET AIR
ELECTRICAL
INLETS
(Either Side)
LIQUID LINE
(Either Side)
2Ć1/8
(54) 6Ć1/2 (165)
4Ć3/4
(121)
AA BB
CCDD
CENTER OF
GRAVITY
EE
FF
CONTROL
BOX
34
(864)
49
(1245)
COMPRESSOR
CONTROL
BOX
ACCESS
3Ć1/4
(83)
OPTIONAL DISCONNECT
(Factory In talled)
OPTIONAL 115 VOLT OUTLET
(Factory In talled In ide Unit)
SERVICE VIEW
15Ć1/2
(394)
OPTIONAL HAIL GUARD
(Field In talled Both Side )
60Ć3/8 (1534) 35Ć3/4 (908)
BASE BASE
SUCTION LINE
(Either Side)
3-1/2
(89)
OPTIONAL HAIL GUARD
(Field In talled Both Side )

Page 4
HP29-090 Unit Part Arrangement
FIGURE 1
OUTDOOR FAN
(B4)
CONTROL BOX
VAPOR LINE
SERVICE VALVE
LOSS OF CHARGE SWITCH (S24) LOW AMBIENT SWITCH
(S11)
FAN GUARD
COMPRESSOR
(B1)
LIQUID LINE
SERVICE VALVE
DEFROST PRESSURE
SWITCH (S46)
REVERSING
VALVE
HIGH PRESSURE SWITCH
(S4)
DEFROST THERMOSTAT
(S6)
HP29-120 Unit Part Arrangement
FIGURE 2
OUTDOOR FANS
(B4, B5)
CONTROL BOX
LOSS OF CHARGE
SWITCH (S24)
FAN GUARD
COMPRESSOR
(B1)
LIQUID LINE
SERVICE VALVE
DEFROST PRESSURE
SWITCH (S46)
DEFROST THERMOSTAT
(S6)
REVERSING
VALVE
LOW AMBIENT SWITCH
(S11) HIGH PRESSURE
SWITCH (S4)
VAPOR LINE
SERVICE VALVE

Page 5
HP29-090 Control Box Arrangement
FIGURE 3
DISCONNECT
SWITCH
S48
COMPRESSOR
CONTACTOR
K1
GROUND
LUG
TRANSFER RELAY
K8
OUTDOOR FAN
RELAY K10
CMCI
DEFROST/TIMER
LOW AMBIENT
BY-PASS RELAY
K58
DEFROST
RELAY K4
RELAY SWITCH
K6
TERMINAL STRIP
TB14
CAPACITOR C1
HP29-120 Control Box Arrangement
FIGURE 4
DISCONNECT
SWITCH
S48
COMPRESSOR
CONTACTOR
K1
CAPACITORS C1, C2
GROUND
LUG
TERMINAL
STRIP TB14
RELAY SWITCH
K6
CMCI DEFROST/TIMER
DEFROST
RELAY K4
LOW AMBIENT
BY-PASS
RELAY K58
TRANSFER
RELAY
K8
OUTDOOR FAN
RELAY K10
OUTDOOR FAN
RELAY K68
LOW AMBIENT
THERMOSTAT S41

Page 6
WARNING
Product contain fibergla wool.
Di turbing the in ulation in thi product during
in tallation, maintenance, or repair will expo e you
to fibergla wool du t. Breathing thi may cau e
lung cancer. (Fibergla wool i known to the State
of California to cau e cancer.)
Fibergla wool may al o cau e re piratory, kin,
and eye irritation.
To reduce expo ure to thi ub tance or for further
information, con ult material afety data heet
available from addre hown below, or contact your
upervi or.
Lennox Indu trie Inc.
P.O. Box 799900
Dalla , TX 75379-9900
Setting the Unit
Re er to unit dimensions on page 1 or sizing mounting
slab, plat orms or supports. Re er to igure 5 or installation
clearances.
Slab Mounting
When installing unit at grade level, install on a level slab
high enough above grade to allow adequate drainage o
water. Top o slab should be located so run-o water rom
higher ground will not collect around unit.
Roof Mounting
Install unit at a minimum o 4 inches above sur ace o the
roo . Care must be taken to ensure weight o unit is properly
distributed over roo joists and ra ters. Either redwood or
steel supports are recommended.
NOTE - 48 IN. (1219 mm) clearance required on top of unit.
INSTALLATION CLEARANCES
FIGURE 5
HP29-090
HP29-120
OUTDOOR COIL
OUTDOOR COIL
OUTDOOR COIL
OUTDOOR COIL
36
(914)*
36
(914)
36
(914)*
36
(914))*
36
(914)
36
(914)*
36
(914)*
36
(914)**
*One of the the e clearance di tance may be reduced to 18" (457 mm).
**Thi clearance may be reduced to 12" (305 mm).
FIGURE 6
CAUTION - Do not walk on unit.
IMPORTANT - ALL PANELS MUST
BE IN PLACE FOR RIGGING.
LIFTING POINT SHOULD BE DIRECTLY
ABOVE CENTER OF GRAVITY
506
626
230
284
UNIT *WEIGHT
LBS. KG.
*Maximum weight with all available
actory-installed accessories.
HP29-090
HP29-120
RIGGING INSTRUCTIONS

Page 7
Rigging the Unit for Lifting
Rig unit or li ting by attaching our cables to holes in unit
base rail. See igure 6.
1 - Detach wooden base protection be ore rigging.
2 - Connect rigging to the unit base using both holes in
each corner.
3 - All panels must be in place (with spreader bars) or rigĆ
ging.
4 - Place ieldĆprovided spreader bars in place just above
top edge o unit. The rame must be o adequate
strength and length. (Spreader bars prevent damage to
top o unit.)
Electrical
Wiring must con orm to current standards o the National
Electric Code (NEC), Canadian Electrical Code (CEC) and
local codes. Re er to the blower coil or urnace installation
instructions or additional wiring application diagrams and
re er to unit rating plate or minimum circuit ampacity and
maximum overcurrent protection size.
WARNING
Unit mu t be grounded in accordance with
national and local code .
Electric Shock Hazard.
Can cau e injury or death.
Line Voltage
To acilitate conduit, knockouts are provided in cabinet
panel. Re er to igure 7 or ield wiring diagram.
NOTE - Units are approved for se with copper cond cĆ
tors only.
24V, Cla II Circuit
24V, Class II circuit connections are made up below control
box. Route wire in conduit to bottom o control box.
NOTE - A complete nit wiring diagram is located inside the
control box panel.
FIGURE 7
RED
YELLOW
GREEN
GREEN
GRAY
RED
YELLOW
GREEN
GREEN
GRAY
HP29 UNIT
THERMOSTAT
CB17/CBH17 BLOWER COIL
(With EH17 Electric Heat Section)
HP29 UNIT THERMOSTAT
CB17/CBH17
BLOWER COIL
FIELD WIRING DIAGRAM -- HP29 WITH AUXILIARY ELECTRIC HEAT
FIELD WIRING DIAGRAM -- HP29 WITHOUT AUXILIARY ELECTRIC HEAT

Page 8
TYPICAL UNIT WIRING DIAGRAM HP29-090
FIGURE 8
*P533542W*
*2P1100*

Page 9
TYPICAL UNIT WIRING DIAGRAM HP29-120
FIGURE 9
*P533543W*
*2P1100*

Page 10
Plumbing
Field re rigerant piping consists o liquid and vapor lines
rom the heat pump unit. Piping may be brought into the
unit through either side. Remove the knockouts on the
mullions and install the provided rubber grommets into the
piping holes. Remove the plugs rom the liquid and vapor
lines. Re er to table 1 or ieldĆ abricated re rigerant line
sizes or runs up to 50 linear eet (15 m).
TABLE 1
REFRIGERANT LINE SIZES
UNIT LIQUID LINE VAPOR LINE
HP29-090 5/8 in. (16 mm) 1-3/8 in. (35 mm)
HP29-120 5/8 in. (16 mm) 1-3/8 in. (35 mm)
Refrigerant Line Brazing Procedure
1 - End o re rigerant line must be cut square, kept round,
ree rom nicks or dents and deburred (I.D. and O.D.)
2 - Wrap a wet cloth around the valve body when brazing
to prevent possible heat damage to the valve core and
port.
3 - Install ilter drier, provided with unit, in the liquid line as
close as possible to the expansion device.
Refrigerant Line Limitation
Unit applications with line set lengths up to 50 linear eet
(15 m) (excluding equivalent length o ittings) may be
installed using re rigerant line sizes as outlined in table 1.
Refrigerant line from 50 to 100 linear feet (15 to 30 m)
hould be ized in accordance with the following ecĆ
tion. The maximum line length is 100 eet (30 m).
Maximum suction rise must not exceed 45 linear eet
(13.7 m) and maximum liquid head must not exceed 45
linear eet (13.7 m).
Re er to the re rigerant piping guideline manual (Corp.
9351-L9) i line lengths exceed 50 eet (15 m). In these
applications, you must install a liquid line solenoid valve
at the evaporator coil. In addition, use expansion valves
only (RFC and capĆtube expansion devices are not acĆ
ceptable). In applications where the lines exceed 75 eet
(23 m), install the solenoid valve with a nonĆrecycling
pumpĆdown control.
NOTE - When refrigerant line solenoid valves are installed,
velocities sho ld not exceed 300 fpm (1.5 m s) in order to
avoid liq id line hammer.
All units are equipped with a low ambient (head pressure)
control to allow or cooling down to 0°F (-18°C).
Due to the additional re rigerant required to ill the lines,
the likelihood o slugging is greatly increased with lines
that are over 50 eet (15 m) in length. An incremental inĆ
crease in liquid line size results in a 40 to 50 percent inĆ
crease in liquid to ill the line. There ore, it is desirable to
use the smallest liquid line size possible.
Pipe Sizing, Line Layout and De ign
[Line et length from 50 - 100 linear feet
(15 - 30 m)]
Start by making a sketch o the system showing relative
locations o the heat pump unit and the indoor coil, length o
each piping segment, elbows, tees, valves, etc. This in orĆ
mation will be used to determine the equivalent length o
the piping run. Also, take note o any di erence in elevation
between the outdoor and indoor units. Vapor and liquid li t
must be considered to ensure proper pipe sizing.
Liquid Line Function and De ign
The liquid line must convey a ull column o liquid rom the
outdoor unit to the metering device at the indoor coil withĆ
out lashing. In order to ensure this, liquid line pressure
drop and pressure across the expansion device and disĆ
tributor must be considered.
TABLE 2
HCFCĆ22 SATURATION TEMPERATURES
(Conden ing Temperature at Different Pre ure )
HCFCĆ22 Pre ure Temperature Table (P ig)
Degree F (°C) HCFC22 Degree F (°C) HCFC22 Degree F (°C) HCFC22 Degree F (°C) HCFC22 Degree F (°C) HCFC22
-40 (-41) 0.6 18 (-8) 41.1 36 (2) 63.3 75 (24) 133.4 120 (49) 262.5
-30 (-34) 4.9 20 (-7) 43.3 38 (3) 66.1 80 (27) 145.0 125 (52) 280.7
-20 (-28) 10.2 22 (-6) 45.5 40 (4) 69.0 85 (29) 157.2 130 (54) 299.7
-10 (-23) 16.6 24 (-4) 47.9 45 (7) 76.6 90 (32) 170.0 135 (57) 319.6
0 (-18) 24.1 26 (-3) 50.3 50 (10) 84.7 95 (35) 183.6 140 (60) 340.3
10 (-12) 32.9 28 (-2) 52.7 55 (13) 93.3 100 (38) 197.9 145 (63) 362.0
12 (-11) 34.9 30 (-1) 55.2 60 (16) 102.4 105 (41) 212.9 150 (66) 384.6
14 (-10) 36.9 32 (0) 57.8 65 (18) 112.2 110 (43) 228.6 155 (68) 406.3
16 (-9) 39.0 34 (1) 60.5 70 (21) 122.5 115 (46) 245.2 160 (71) 433.3

Page 11
HCFCĆ22 LIQUID LINE PRESSURE DROP/VELOCITY
At 45°F Evaporating Temperature and 125°F Conden ing Temperature
30
25
20
15
10
9
8
7
6
5
4
3
2
1.5
1.0
.9
.8
.7
10 9 8 7 6 5 4 3 2 1.5 1.0 .9 .8 .7 .6 .5 .4 .3 .2
HCFCĆ22 LIQUID LINE PRESSURE DROP (lb ./100 Feet)
COOLING CAPACITY (TONS)
30
25
20
15
10
9
8
7
6
5
4
3
2
1.5
1.0
.9
.8
.7
COOLING CAPACITY (TONS)
10 9 8 7 6 5 4 3 2 1.5 1.0 .9 .8 .7 .6 .5 .4 .3 .2
HCFCĆ22 LIQUID LINE PRESSURE DROP (lb ./100 Feet)
NOTE - Shaded area denotes nacceptable velocity range.
FIGURE 10
12.5
To se this chart, first find capacity (tons) on left side of chart. To find pipe size, proceed right to smallest pipe size. Press re drop (vertical line)
and velocity (diagonal lines) can then be determined for the pipe size selected. For example, for 10 ton nit, select 5/8 in. O.D. line.
EXAMPLE:
10 TON UNIT
5/8 IN. O.D. LINE 4.25
PSI DROP PER 100
FEET
275 FPM VELOCITY
40 30 20 15
40 30 20 15

Page 12
TABLE 3
Equivalent Length in Feet of Straight Pipe
for Valve and Fitting
Line
Size
O.D.
in.
Globe
Valve
Angle
Valve
90°
Long*
Radiu
Elbow
45°
Long*
Radiu
Elbow
Tee
Line
Tee
Branch
3/8 7 4 0.8 0.3 0.5 1.5
1/2 9 5 0.9 0.4 0.6 2.0
5/8 12 6 1.0 0.5 0.8 2.5
3/4 14 7 1.3 0.6 0.9 3.0
7/8 15 8 1.5 0.7 1.0 3.5
1Ć1/8 22 12 1.8 0.9 1.5 4.5
1Ć3/8 28 15 2.4 1.2 1.8 6.0
1Ć5/8 35 17 2.8 1.4 2.0 7.0
2Ć1/8 45 22 3.9 1.8 3.0 10
2Ć5/8 51 26 4.6 2.2 3.5 12
Long radi s elbow. M ltiply factor by 1.5 for short radi s elbow eq ivaĆ
lent length.
Lennox equipment above ive tons in capacity typically opĆ
erates at a saturated condensing temperature o 125°F
(280psi per table 2). Lennox equipment is designed to hold
a charge allowing 10°F subcooling at 95°F ambient. The
condensing temperature and the subcooling are used to
calculate the maximum allowable pressure drop as deĆ
tailed below.
NOTE - 95°F ambient is an arbitrary temperat re chosen to
represent typical s mmer operating conditions sed to calĆ
c late maxim m allowable press re drop. This temperaĆ
t re (and the corresponding s bcooling) may vary with reĆ
gional climate.
Example -- Calculating maximum allowable pressure
drop: Find the maximum allowable liquid line pressure
drop o a unit operating at 10°F subcooling and 125°F (280
psi) condensing temperature. Subtract 10°F subcooling
temperature rom 125°F condensing temperature to equal
115°F subcooled liquid temperature (245 psi / point at
which lash gas will begin to orm). Subtract 245 psi subĆ
cooled pressure rom 280 psi condensing pressure to ind a
maximum allowable pressure drop o 35 psi.
To calculate actual pressure drop in the liquid line, calcuĆ
late pressure drop due to riction and pressure drop due to
vertical li t and add the two.
Pressure drop due to riction in the pipe or other devices
must all be considered. Pressure drop ratings or di erent
pipe sizes are given in igure 10. Pressure drop ratings o
ieldĆinstalled devices are typically supplied by the
manu acturer.
Pressure drop due to vertical li t (1/2 pound per oot) is typĆ
ically high and can be a limiting actor in the design o the
system.
The liquid re rigerant pressure must be su icient to produce
the required low through the expansion device. Liquid reĆ
rigerant ( ree o lash gas) should be delivered to the expanĆ
sion valve at a minimum o 175psi to ensure the 100 psi necĆ
essary to produce ull re rigerant low at the rated capacity.
Example -- Liquid Line Pipe Sizing
Given: 10Ćton heat pump unit on ground level with a 10Ćton
indoor coil on the third level above ground and a total o 96
linear eet o piping. Unit is charged with 10°F subcooling at
125°F condensing temperature (280 psi HCFCĆ22 liquid).
Re er to igure 11.
Find: Select tube size rom igure 10.
10 TON
HEAT PUMP
UNIT
10 TON
INDOOR
COIL
53 FT.
3 FT. 40 FT.
GIVEN: 10 TON EVAPORATOR
10 TON HEAT PUMP UNIT
WITH 10°F SUBCOOLING at 125°F
LENGTH OF LINE -- 96 FT.
FIND: LIQUID LINE SIZE
LIQUID LINE SIZING EXAMPLE
FIGURE 11
FILTER/DRIER
4.25 psi
100 t. x 98 t. = 4.17psi
ANSWER; 5/8 IN. O.D. COPPER TUBING CAN BE USED. PRESSURE LOSS DOES NOT
EXCEED MAXIMUM ALLOWABLE PRESSURE DROP (6°F TO 7°F SUBCOOLING WILL
BE AVAILABLE AT THE EXPANSION VALVE) AND VELOCITY IS ACCEPTABLE.
SELECT A PROPOSED TUBING
SIZE: 5/8in. COPPER
SOLUTION: PRESSURE DROP
CANNOT EXCEED 35 psi.
TOTAL PRESSURE DROP=
TOTAL FRICTION LOSSES + LIFT LOSSES + FILTER/DRIER
TOTAL EQUIVALENT LENGTH =
LINEAR LENGTH + EQUIVALENT LENGTH OF FITTINGS
TWO 90° LONG RADIUS ELBOWS @ 5/8in. O.D. = 1 t. EQUIV. FT. EA.
TOTAL EQUIVALENT LENGTH = 98 t.
TOTAL FRICTION LOSSES =
LIFT LOSSES = 40 t. x 1/2psi per oot = 20psi
TOTAL PRESSURE DROP = 20 psi + 4.17 psi + 1 psi = 25.17 psi
FILTER DROP = 1 psi (by manu acturer)
Figure 10 illustrates the relationship between liquid line sizĆ
ing, pressure drop per 100 eet, velocity range and tonĆ
nage. Enter igure 10 rom the le t and extend to the right to
the smallest tube size that will not exceed 300 pm velocity.
Solution: For a 10Ćton system, 5/8 inch O.D. line with 4.25
psi per 100 eet drop (per igure 10) is selected. Now, calcuĆ
late pressure drop due to riction and liquid li t to determine i
this is a good selection.
The total riction drop or the application will include 96 eet
o 5/8 inch O.D. pipe plus 1 equivalent oot per elbow (two
elbows) to equal 98 equivalent eet.
In a 10Ćton system, expect 4.25 psi drop per 100 eet o
5/8 inch O.D. copper (per igure 10). Multiply 4.25/100
by 98 equivalent eet to calculate the total riction loss o
4.17 psi.
Add the pressure drop caused by vertical li t. When
HCFCĆ22 re rigerant is used, there is 1/2 psi pressure drop
per oot o vertical li t. In this application, which has a
40Ćfoot (12 m) vertical lift, add a 20 psi pressure drop
because of the lift.

Page 13
Finally, consider the impact o the ilter drier to the liquid,
line which has a 1 psi pressure drop (this number provided
by manu acturer).
Add the three components o pressure drop together to
ind that the total pressure drop in this 5/8 inch line equals
25.17 psi which is well within our acceptable range. The
5/8 inch line, there ore, is a good selection because it is
well below the maximum allowable pressure drop, is in a
satis actory velocity range, uses minimum re rigerant and
provides su icient pressure at the expansion valve.
Alternative Sizing: Suppose 3/4 inch O.D. line with 1.6
psi drop per 100 eet had been selected. The total equivaĆ
lent length is equal to the linear length (96 eet) plus the
equivalent length o the ittings ( rom table 3, two 90° ells
at 1.25 eet each). The total equivalent length is 98.5 eet.
The total riction drop would have been 1.6/100 multiplied
by 98.5 = 1.57 psi. When the pressure drop due to li t (20
psi) and the ilter drier (1 psi) are added we ind that the
total pressure drop or 3/4 inch line equals 22.57 psi.
Though the 3/4 inch line provides a lower pressure drop,
the larger diameter pipe will require more re rigerant
which will increase the risk o re rigerant slugging. In addiĆ
tion, the smaller line will be less costly. The smaller line
should be used.
Vapor Line Function and De ign
The vapor line returns re rigerant vapor and oil rom the
evaporator to the compressor. Vapor line design is critical.
The design must minimize pressure loss in order to
achieve maximum unit e iciency and provide adequate oil
return to the compressor under all conditions.
Because oil separates rom re rigerant in the evaporator,
the vapor velocity must be adequate to sweep the oil along
the pipe. Horizontal vapor lines require a minimum o 800
pm velocity or oil entrainment. In order to ensure oil enĆ
trainment, vapor line risers require a minimum velocity o
1200 pm (1500 pm is pre erred) regardless o the length
o the riser.
Figure 14 illustrates the relationship between vapor line
sizing, pressure drop, velocity and cooling capacity. Use
this chart to determine vapor line pressure drop and velocĆ
ity. As the pipe size increases, so does the capacity reĆ
quired to ensure oil entrainment.
Vertical li t has no signi icant e ect on system capacity.
However, systems lose approximately 1 percent o capacĆ
ity or every pound o pressure drop due to riction in the vaĆ
por line. In order to calculate capacity loss, irst estimate
pressure drop in the total equivalent length o the piping run
(re er to igure 14). Capacity ratings given in the Lennox
Engineering Handbook include the loss or a 25 eet re rigĆ
erant line. There ore, subtract the pressure loss o 25 eet
o piping rom the total calculated or your particular apĆ
plication.
OUTDOOR
UNIT
INDOOR
UNIT
DETERMINING VAPOR LINE CAPACITY LOSS
IF PRESSURE DROP IS KNOWN
Total Pressure Drop
For Equivalent Length
25 t.
Line
Once Pressure Drop Is Found:
Btuh lost = 1% x (Total Press. Drop minus 25 t.) x rated capacity
FIGURE 12
Total Pressure Drop
Minus Press. Drop in
25 t. o Line
When an indoor coil is located above or on the same level
as the heat pump, the vapor line must rise to the top o the
evaporator. See igure 13. This helps prevent liquid rom
migrating to the compressor during the o cycle. Traps
should also be installed at the bottom o all vertical risers or
migration protection in the o cycle.
OUTDOOR
UNIT
INDOOR
COIL
VAPOR LINE PIPING
Indoor Coil Above or On Same Level with Outdoor Unit
FIGURE 13
OUTDOOR
UNIT
INDOOR
COIL
VAPOR LINE
VAPOR LINE
If eq ipment is on same level, inverted trap sho ld still be sed
in order to prevent liq id migration to compressor d ring off cycle.
TRAP
RAISE PIPE
TO TOP LEVEL
OF COIL
INSTALL TRAPS AT
BOTTOM OF
EACH RISER
Horizontal vapor lines should be level or slightly sloped toĆ
ward the heat pump unit. Pipe must avoid dips or low spots
that can collect oil. For this reason, hard copper should be
used, especially on long horizontal runs.
As with liquid line sizing, begin by making a sketch o the
layout complete with ittings, driers, valves etc. Measure
the linear length o each line and determine the number o
ells, tees, valves, driers etc. Add equivalent length o itĆ
tings (table 3) to linear length o pipe to get total equivalent
length used in determining riction loss. Again, re er to
manu acturer's data or pressure drop in ormation on acĆ
cessory components. The resultant pressure drop must be
considered.

Page 14
HCFCĆ22 VAPOR LINE PRESSURE DROP/VELOCITY PER 100 FT. OF LINE
At 45°F Evaporating Temperature and 125°F Conden ing Temperature
30
25
20
15
10
9
8
7
6
5
4
3
2
1.5
1.0
.9
.8
.7
10 9 8 7 6 5 4 3 2 1.5 1.0.9 .8 .7 .6 .5 .4 .3 .2
HCFCĆ22 VAPOR LINE PRESSURE DROP (lb ./100 Feet)
COOLING CAPACITY (TONS)
30
25
20
15
10
9
8
7
6
5
4
3
2
1.5
1.0
.9
.8
.7
COOLING CAPACITY (TONS)
10 9 8 7 6 5 4 3 2 1.5 1.0.9 .8 .7 .6 .5 .4 .3 .2
HCFCĆ22 VAPOR LINE PRESSURE DROP (lb ./100 Feet)
NOTE - Shaded area denotes nacceptable velocity range.
FIGURE 14
40 30 20 15
40 30 20 15
EXAMPLE: 10 TON UNIT
1Ć3/8 IN. O.D. LINE
3.3 PSI DROP PER 100 FEET
2400 FPM VELOCITY
12.512.5
To se this chart, first find capacity (tons) on left side of chart. To find pipe size, proceed right to smallest pipe size. Press re drop (vertical line) and
velocity (diagonal lines) can then be determined for the pipe size selected. For example, for 10 ton nit, select 1Ć3/8 in. O.D. line.
Example -- Vapor Line Pipe Sizing
Given: 7Ć1/2 ton heat pump with indoor coil lower than outĆ
door coil. Application includes 82 linear eet o piping and 4
ells. There is a 20Ć oot vertical li t and 62 eet o horizontal
run. Re er to igure 15.
Find: Select tube size rom igure 14.
Solution: 1Ć1/8 inch O.D. line with 6 psi per 100 eet presĆ
sure drop and 2900 pm velocity is selected. Now, calculate
pressure drop due to riction to determine i this is a good
selection.

Page 15
FIGURE 15
INDOOR COIL
EXAMPLE Ć Indoor Coil Below Outdoor Unit
VAPOR LINE
SUCTION RISER
OIL TRAP
20 FT.
2 FT.
60 FT.
From table 3, our ells at 1.8 equivalent eet each equals 7.2
equivalent eet. When added to the 82 eet o pipe, the total
equivalent eet becomes 89.2 eet (round up to 90 eet).
Multiply 6/100 by 90 equivalent eet to calculate total riction
loss o 5.4 psi.
Use igure 14 to calculate the pressure drop in 25 eet o 1Ć1/8
inch line. Multiply 6/100 by 25 eet to calculate riction loss o
1.5 psi. This loss has already been included in the capacity
given in Lennox' Engineering Handbook, so it should be subĆ
tracted rom the total.
The capacity lost in the total equivalent length" o the reĆ
rigerant line (using igures 12 and 14) equals 1 percent x
(5.4 - 1.5) x 90,000.
Btuh lost= 0.01 x (3.9) x 90,000 = 3510
Capacity loss or the line selected is approximately 3.9
percent.
The preceding calculation shows that this is a workable
system, but it will result in losses in both capacity and e iĆ
ciency.
Alternative Sizing: Using the same (7Ć1/2 ton) example,
this time select 1Ć3/8 inch O.D. line. 1Ć3/8 inch O.D. line with
2 psi per 100 eet pressure drop has 1760 pm velocity. Now
calculate pressure drop due to riction loss to determine i
this is a better selection.
From igure 3, our ells at 2.4 equivalent eet each equals
9.6 equivalent eet. When added to the 82 eet o pipe, the
total equivalent eet becomes 91.6 eet (round up to 92
eet).
Multiply 2/100 by 92 equivalent eet to calculate total riction
loss o 1.8 psi.
Use igure 14 to calculate the pressure drop in 25 eet o
1Ć3/8 inch line. Multiply 2/100 by 25 eet to calculate riction
loss o 0.5 psi. This loss has already been included in the
capacity given in Lennox' Engineering Handbook, so it
should be subtracted rom the total.
The capacity lost in the total equivalent length" o the reĆ
rigerant line (using igures 12 and 14) equals 1 percent x
(1.8 - 0.5) x 90,000.
Btuh lost= 0.01 x (1.3) x 90,000 = 1170
Capacity loss or the line selected is approximately 1.3
percent.
The conditions in this example will allow either 1Ć1/8 inch or
1Ć3/8 inch vapor line to be used, since capacity loss is miniĆ
mized and velocity is su icient to return oil to the compresĆ
sor.
Service Valve
The liquid line and vapor line service valves and gauge
ports are accessible inside o the unit. These gauge ports
are used or leak testing, evacuating, charging and checkĆ
ing charge.
IMPORTANT - Service valves are closed to line set conĆ
nections. Do not open ntil refrigerant lines and indoor coil
have been leak tested and evac ated. All preca tions
sho ld be exercised to keep the system free from dirt,
moist re and air.
Liquid Line Service Valve
All HP29 units use liquid line service valves as shown in igĆ
ure 16. A Schrader valve is actory installed. A service port
is supplied to protect the Schrader valve rom contaminaĆ
tion and serve as the primary leak seal.
LIQUID LINE SERVICE VALVE (VALVE OPEN)
FIGURE 16
SCHRADER
VALVE
SERVICE PORT
SERVICE
PORT
CAP
INSERT HEX
WRENCH HERE
INLET (TO
INDOOR
COIL)
OUTLET (TO
COMPRESSOR)
STEM CAP
SCHRADER VALVE OPEN
TO LINE SET WHEN VALVE IS
CLOSED (FRONT SEATED)
SERVICE
PORT
SERVICE
PORT
CAP
RETAINING RING STEM CAP
INSERT HEX
WRENCH HERE
LIQUID LINE SERVICE VALVE (VALVE CLOSED)
(VALVE
FRONT
SEATED)
INLET (TO
INDOOR
COIL)
OUTLET (TO
COMPRESSOR)

Page 16
To Acce 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 inger tight, then an additional 1/6 turn.
To Open Liquid Line Service Valve:
1 - Remove stem cap with an adjustable wrench.
2 - Using service wrench and 5/16 inch hex head extenĆ
sion back the stem out counterclockwise until the valve
stem just touches the retaining ring.
3 - Replace stem cap. Tighten inger tight, then tighten an
additional 1/6 turn.
WARNING
Do not attempt to back eat thi valve. Attempt to
back eat thi valve will cau e nap ring to explode
from valve body under pre ure of refrigerant. PerĆ
onal injury and unit damage will re ult.
To Clo e Liquid Line Service Valve:
1 - Remove stem cap with an adjustable wrench.
2 - Using service wrench and 5/16 inch hex head extension,
turn stem clockwise to seat the valve. Tighten irmly.
3 - Replace stem cap and tighten inger tight, then tighten
an additional 1/6 turn.
Vapor Line Service Valve
VAPOR LINE (BALL TYPE) SERVICE VALVE
(VALVE OPEN)
SCHRADER VALVE
SERVICE
PORT
STEM CAP
STEM
USE ADJUSTABLE WRENCH
ROTATE STEM CLOCKWISE 90° TO CLOSE
ROTATE STEM COUNTERCLOCKWISE 90° TO OPEN
BALL
(SHOWN OPEN)
TO OUTDOOR COIL
TO INDOOR COIL
SERVICE PORT
CAP
FIGURE 17
All HP29 units are equipped with a ull-service ball valve
on the vapor line, as shown in igure 17. One service port
that contains a Schrader valve core is present in this
valve. A cap is also provided to seal o the service port.
The valve is not rebuildable so it must always be replaced
i ailure has occurred.
Opening the Vapor Line Service Valve
1 - Remove the stem cap with an adjustable wrench.
2 - Using a service wrench, turn the stem counterclockĆ
wise or 1/4 o a turn.
3 - Replace the stem cap and tighten it irmly.
Clo ing the Vapor Line Service Valve
1 - Remove the stem cap with an adjustable wrench.
2 - Using a service wrench, turn the stem clockwise or 1/4
o a turn.
3 - Replace the stem cap and tighten it irmly.
Leak Te ting
A ter the line set has been connected to the indoor and outĆ
door units, the line set connections and indoor unit must be
checked or leaks.
WARNING
Never u e oxygen to pre urize refrigeration or air
conditioning y tem. Oxygen will explode on conĆ
tact with oil and could cau e per onal injury. When
u ing high pre ure ga uch a nitrogen or CO2 for
thi purpo e, be ure to u e a regulator that can conĆ
trol the pre ure down to 1 or 2 p ig (6.9 to 13.8 kPa).
U ing an Electronic Leak Detector or Halide
1 - Connect the hoses to the service ports With both manĆ
i old valves closed, open the valve on the HCFCĆ22
cylinder (vapor only). Open the liquid line and vapor
line service valves.
2 - Open the high pressure side o the mani old to allow
HCFCĆ22 into the line set, indoor unit, and the outdoor
unit. Weigh in a trace amount o HCFCĆ22. [A trace
amo nt is a maxim m of 2 o nces (57g) refrigerant or
3 po nds (31 kPa) press re]. Close the valve on the
HCFCĆ22 cylinder and the valve on the high pressure
side o the mani old gauge set. Disconnect HCFCĆ22
cylinder.
3 - Connect a cylinder o nitrogen with a pressure regulatĆ
ing valve to the center port o the mani old gauge set.
4 - Connect the high pressure hose o the mani old gauge
set to the service port o the vapor line valve. (Normally,
the high press re hose is connected to the liq id line
port, however, connecting it to the vapor port better
protects the manifold ga ge set from high press re
damage.)
5 - Connect the nitrogen cylinder to the center port on the
mani old gauge set.
6 - Adjust nitrogen pressure to 150 psig (1034 kPa). Open
the valve on the high side o the mani old gauge set
which will pressurize line set and indoor unit.
7 - A ter a short period o time, open a system port to make
sure the re rigerant added is adequate to be detected.
(Amounts o re rigerant will vary with line lengths.)
Check all joints or leaks, then purge the nitrogen and
HCFCĆ22 mixture. Correct any leaks and recheck.

Page 17
Evacuation & Dehydration
IMPORTANT
Unit are hipped with a holding charge of dry air and
helium which mu t be removed before the unit i
evacuated and charged with refrigerant.
Evacuating the system o noncondensables is critical or
proper operation o the unit. Noncondensables are gases
that will not condense under temperatures and pressures
present during operation o an air conditioning system. NonĆ
condensables and water vapor combine with re rigerant to
produce substances that corrode copper piping and comĆ
pressor parts.
1 - Connect mani old gauge set to the service valve ports
as ollows: low pressure gauge to vapor line service
valve; high pressure gauge to liquid line service valve.
IMPORTANT - Compressors (as with any refrigerant
compressor) sho ld never be sed to evac ate a refrigĆ
eration or air conditioning system.
NOTE - A temperat re vac m ga ge, merc ry vac Ć
m or thermoco ple ga ge sho ld be sed. The s al
Bo rdon t be ga ges are inacc rate in the vac m
range.
2 - Open the vapor line and liquid line valves to evacuate
the unit.
3 - Connect the vacuum pump (with vacuum gauge) to the
center port o the mani old gauge set.
4 - Open both mani old valves and start vacuum pump.
5 - Evacuate the outdoor unit, the line set, and the indoor
unit to an ab olute pre ure o 23 mm o mercury or
approximately 1 inch o mercury. During the early
stages o evacuation, it is desirable to close the manĆ
i old gauge valve at least once to determine i there is a
rapid rise in ab olute pre ure. A rapid rise in presĆ
sure indicates a relatively large leak. I this occurs, the
leak testing procedure must be repeated.
NOTE - The term absolute pressure means the total
act al press re within a given vol me or system,
above the absol te zero of press re. Absol te presĆ
s re in a vac m is eq al to atmospheric press re miĆ
n s vac m press re.
6 - When the absolute pressure reaches 23 mm o mercuĆ
ry, close the mani old gauge valves, turn o the vacuĆ
um pump and disconnect the mani old gauge center
port hose rom vacuum pump. Attach the mani old cenĆ
ter port hose to a nitrogen cylinder with pressure reguĆ
lator set to 150 psig (1034 kPa) and purge the hose.
Open the mani old gauge valves to break the vacuum
in the line set and indoor unit. Close the mani old
gauge valves.
CAUTION
Danger of Equipment Damage.
Avoid deep vacuum operation. Do not u e compre Ć
or to evacuate a y tem.
Extremely low vacuum can cau e internal arcing
and compre or failure.
Damage cau ed by deep vacuum operation will void
warranty.
7 - Shut o the nitrogen cylinder and remove the mani old
gauge hose rom the cylinder. Open the mani old
gauge valves to release the nitrogen rom the line set,
indoor unit, and the outdoor unit.
8 - Reconnect the mani old gauge to the vacuum pump.
Turn the pump on and continue to evacuate the outĆ
door unit, line set, and indoor unit. Evacuate until the
absolute pressure does not rise above .5 mm (500 miĆ
crons) o mercury within a 20-minute period a ter you
shut o the vacuum pump and close the mani old
gauge valves.
10- When the absolute pressure requirement above has
been met, disconnect the mani old hose rom the vacuĆ
um pump and connect it to an upright cylinder o
HCFCĆ22 re rigerant. Open the mani old gauge valves
to break the vacuum in the outdoor unit, line set, and inĆ
door unit. Close mani old gauge valves. Shut o
HCFCĆ22 cylinder and remove the mani old gauge set.
Start-Up
IMPORTANT
Crankca e heater hould be energized 24 hour beĆ
fore unit tart-up to prevent compre or damage a
a re ult of lugging.
1 - Rotate the an to check or rozen bearings or binding.
2 - Inspect all actory and ield-installed wiring or loose
connections.
3 - Re er to charging section to accurately charge and
check the charge on this unit.
4 - Check voltage supply at the disconnect switch. The
voltage must be within range listed on unit nameplate.
I not, do not start equipment until the power company
has been consulted and the voltage condition corĆ
rected.
5 - Set thermostat or a cooling demand, turn on power to
blower and close heat pump unit disconnect switch to
start.
6 - Recheck unit voltage with unit running. Power must be
within range shown on unit nameplate. Check amperĆ
age draw o unit. Re er to unit nameplate or correct
running amps.

Page 18
Three-Pha e Compre or Rotation
ThreeĆphase scroll compressors must be phased sequenĆ
tially to ensure that the compressor rotates and operates
correctly. When the compressor starts, a rise in discharge
and drop in suction pressures indicate proper compressor
phasing and operation. I discharge and suction pressures
do not per orm normally, ollow the steps below to correctly
phase in the unit.
1 - Disconnect the power to the unit.
2 - Reverse any two ield power leads to the unit.
3 - Reconnect the power to the unit.
The discharge and suction pressures should operate withĆ
in their normal startĆup ranges.
NOTE - The compressor's noise level will be significantly
higher when the phasing is incorrect. The compressor will
not provide cooling when the nit is not correctly phased.
Contin ed backward operation of the compressor to d e to
incorrect phasing will ca se the compressor to cycle on inĆ
ternal protector.
Charging
Units are shipped with a holding charge o dry air and/or
helium. which must be removed be ore the unit is evacuĆ
ated and charged with re rigerant. In new installations,
the recommended and most accurate method o chargĆ
ing is to weigh the re rigerant into the unit as outlined in
table 4 and the ollowing procedure.
Weighing in the Charge
(TXV Systems, < 60°F Outdoor Temperature)
1 - Recover the re rigerant rom the unit.
2 - Conduct a leak check, then evacuate as previously
outlined.
3 - Weigh in the actory charge as shown on the outdoor
unit's rating plate.
Checking Charge U ing Normal Operating Pre ure
I weighing acilities are not available, or i charge needs
to be checked, use the ollowing method:
1 - Attach gauge mani olds and operate unit in cooling
mode until system stabilizes (approximately ive minĆ
utes).
2 - Use a thermometer to accurately measure the outdoor
ambient temperature.
3 - Apply the outdoor temperature to table 5 to determine
normal operating pressures.
4 - Compare the normal operating pressures to the presĆ
sures obtained rom the gauges. Minor variations in
these pressures may be expected due to di erences in
installations. Signi icant di erences could mean that
the system is not properly charged or that a problem
exists with some component in the system. Correct
any system problems be ore proceeding.
5 - Use approach method to con irm the readings, or adĆ
just the re rigerant charge.
Charge Verification
The re rigerant charge can be veri ied using the approach
method i the outdoor ambient temperature is 60°F or
above. I the outdoor ambient temperature is below 60°F,
you must weigh the re rigerant into the unit to ensure propĆ
er charging.
TABLE 4
UNIT MODEL
NUMBER
MATCHED
INDOOR UNIT
HCFCĆ22 FOR 25 FEET
(7.6 m) OF LINE
LIQUID LINE
DIAMETER
ADJUSTMENT PER
FOOT (.3 m) OF LINE*
HP29 090 2
CB17/CBH17 95
23 lb (10 4 k )
5/8 in. (16 mm) 1.8 oz. (51g)
HP29-090-2 CB17/CBH17-95 23 lbs. (10.4 kg) 3/4 in. (19 mm) 2.6 oz. (74g)
HP29 120 2
CB17/CBH17 135
31 lbs (14 1 kg)
5/8 in. (16 mm) 1.8 oz. (51g)
HP29-120-2 CB17/CBH17-135 31 lbs. (14.1 kg) 3/4 in. (19 mm) 2.6 oz. (74g)
* If line length is greater than 25 feet (7.62 m), add this amo nt. If line length is less than 25 feet (7.62 m), s btract this amo nt.
NOTE - Refrigerant line sets sho ld not be longer than 100 feet (30.5 m). Refrigerant line losses ded ct from the net capacity of the sysĆ
tem. Additional refrigerant req ired for s ch systems may also pset the refrigerantĆtoĆoil ratio.
TABLE 5
NORMAL OPERATING PRESSURES
Outdoor Coil
Entering Air
Temperature
HP29-090*
Di charge
+ 10 p ig
HP29-090*
Vapor
+ 5 p ig
HP29-120**
Di charge
+ 10 p ig
HP29-120**
Vapor
+ 5 p ig
65°F (18°C) 188 69 180 64
75°F (24°C) 216 71 206 66
85°F (29°C) 248 72 236 67
95°F (35°C) 283 74 269 69
105°F (41°C) 319 76 304 70
115°F (46°C) 360 78 345 72
* HP29-090 tested with CB17/CBH17-95V. **HP29-120 tested with CB17/CBH17-135V.

Page 19
Approach Method of Charge Verification
(Expansion Valve Systems, > 60°F Outdoor Temp.)
The approach method should be used to veri y the charge
a ter the normal operating pressures have been con irmed
to be within the ranges given in table 5. Do not use the apĆ
proach method i system pressures do not match the presĆ
sures given in table 5. The approach method is not valid or
grossly overĆ or undercharged systems. A ter you have
taken the outdoor ambient and liquid line temperature
readings with the unit operating in high peed, subtract
the outdoor ambient temperature rom the liquid line temĆ
perature to determine the Approach Temperature. (Liquid
line °F - Outdoor Ambient °F = Approach temperature)
The resulting di erence (Approach Temperature) should
agree with the values given in table 6. I not, add re rigerant
to lower the approach temperature or recover re rigerant
rom the system to increase the approach temperature.
TABLE 6
APPROACH METHOD
Model
No.
Liquid Temp. Minu
Ambient Temp. °F (°C)
HP29-090 9.2 + 1 (5.0 + .5)
HP29-120 11.3 + 1 (6.0 + .5)
Note - For best res lts, the same thermometer sho ld be sed to
check both o tdoor ambient and liq id temperat res.
Sy tem Operation
Heat pump and indoor blower cycle on demand rom room
thermostat. When thermostat blower switch is moved to
ON position, indoor blower operates continuously.
HP29 units are equipped with external, bellyĆband crankĆ
case heaters. The crankcase heater should be energized
24 hours be ore unit start-up to prevent compressor damĆ
age as a result o slugging.
The scroll compressor manu acturer stipulates that all heat
pumps are to be equipped with an SPST high temperature
discharge line thermostat. I the discharge line ever reachĆ
es or exceeds 275±5°F, the thermostat will open the comĆ
pressor circuit. The switch automatically resets as the line
temperature decreases to 225±5°F.
HP29 units are equipped with a high pressure switch that is
located in the discharge line o the compressor. The switch
(SPST, manual reset, normally closed) removes power
rom the compressor when discharge pressure rises above
actory setting at 410 + 10 psi.
HP29 units are equipped with a loss o charge switch that is
located in the liquid line immediately a ter the condenser
coil. The switch (SPST, auto-reset, normally closed) reĆ
moves power rom the compressor when the liquid line
pressure drops below the 25+5 psig setting. The switch auĆ
tomatically resets once the pressure reaches 55+5 psig.
Each outdoor unit is equipped with a bypass relay which
switches control o the outdoor an(s) to the low ambient
pressure switch (and low ambient thermostat on
HP29-120) during low ambient operation. The bypass
relay is wired parallel to the compressor reversing valve
and is only energized during the cooling cycle.
Each HP29 heat pump is equipped with a low ambient
pressure switch which cycles the outdoor an during low
ambient operation. The normally closed switch opens
when liquid line pressure drops to 150 + 10 psig. The switch
automatically resets when the liquid line pressure rises to
275 + 10 psig.
HP29-120 units are equipped with a sur aceĆmounted low
ambient thermostat (normally closed) which cycles one
outdoor an during low ambient cooling operation. The
switch opens on temperature all at 55 + 5°F and automatiĆ
cally resets when temperature rises to 65 + 5°F.
The defro t thermo tat, defro t pre ure witch and
the defro t control work together to ensure that the heat
pump outdoor coil does not ice excessively during the heatĆ
ing mode.
The defro t thermo tat is located on the liquid line beĆ
tween the check/expansion valve and the distributor. When
the liquid line temperature drops below 35°F, the switch
closes and signals the defro t control that a de rost cycle
is needed. I the de rost thermostat is still closed a ter the
ield-selected compressor run time (30, 60 or 90 minutes)
has been completed, a de rost cycle begins. The de rost
cycle is limited to a maximum o 14 minutes. The defrost
cycle is terminated by the defrost press re switch. The deĆ
fro t pre ure witch is located on the heating cycle vaĆ
por line (cooling/de rost cycle discharge line). The normally
closed switch opens on a pressure rise at 275 + 10 psi to
terminate a de rost cycle. The pressure switch automatiĆ
cally resets.
The de rost control includes a pressure switch sa ety circuit
that allows or the application o an additional pressure
switch. The de rost control will lock out unit operation on the
third instance (during one demand cycle) that any auto-reĆ
set switch opens this circuit. The diagnostic LEDs will indiĆ
cate a pressure switch lockout. Re er to typical unit diaĆ
gram or application o an optional loss o charge switch.
The de rost control also provides terminal connections or
an ambient thermistor and a service light. Re er to igure 18
or de rost control parts arrangement and compressor run
timing pin adjustment. Table 7 details de rost control diagĆ
nostic LED codes.
TABLE 7
DEFROST CONTROL BOARD DIAGNOSTIC CODES
Mode LED #1 LED #2
Normal Operation/
Power to board
Simultaneous
Flash
Simultaneous
Flash
Time Delay to
Protect Compressor
Alternating
Flash
Alternating
Flash
Pressure Switch Open O On
Pressure Switch
Lockout On O
Board Mal unction On On

Page 20
DEFROST CONTROL BOARD
FIGURE 18
24V
TERMINAL
STRIP
DIAGNOSTIC
LED
PRESSURE
SWITCH
SAFETY
CIRCUIT
DEFROST
INTERVAL
TIMING PINS
AMBIENT
THERMISTOR
CONNECTION
NOTE- There is an internal
jumper between
PS1 and PS2 terminals.
SERVICE
LIGHT
CONNECTIONS
90 TEST
60 30
TIMING
JUMPER
TIMING PINS
(seconds)
Maintenance
At the beginning o each cooling season, the system
should be checked as ollows:
Outdoor Unit
1 - Clean and inspect the condenser coil. You can lush
the coil with a water hose.
2 - The outdoor an motor is prelubricated and sealed. No
urther lubrication is necessary.
3 - Visually inspect connecting lines and coils or evidence
o oil leaks.
4 - Check wiring or loose connections.
5 - Check or correct voltage at the unit while the unit is opĆ
erating and while it is o .
6 - Check amp-draw o the outdoor an motor.
Unit nameplate _________ Actual ____________ .
Check amp-draw o the compressor.
Unit nameplate _________ Actual ____________ .
NOTE - If the owner complains of ins fficient cooling,
ga ge the nit and check the refrigerant charge. ReĆ
fer to section on refrigerant charging in this instr cĆ
tion.
Indoor Coil
1 - I necessary, clean the coil.
2 - Check connecting lines and coils or evidence o oil
leaks.
3 - I necessary, check the condensate line and clean it.
Indoor Unit
1 - Clean or change ilters.
2 - Adjust the blower speed or cooling. Measure the presĆ
sure drop over the coil to determine the correct blower
CFM. Re er to the unit in ormation service manual or
pressure drop tables and procedure.
3 - On belt drive blowers, check the belt or wear and propĆ
er tension.
4 - Check all wiring or loose connections.
5 - Check or correct voltage at the unit (blower operating).
6 - Check amp-draw on blower motor.
Unit nameplate_________ Actual ____________.
WARNING
Electric hock hazard. Can cau e injuĆ
ry or death. Before attempting to perĆ
form any ervice or maintenance, turn
the electrical power to unit OFF at di Ć
connect witch(e ). Unit may have
multiple power upplie .
Job Name
Job Location
Installer
Unit Model No.
Nameplate Voltage
Minimum Circuit Ampacity
Maximum Overcurrent Protection Size
Re rigerant Lines:
Service Valves Fully Opened?
Outdoor Fan Checked?
Job No.
City
City
Serial No.
Date
State
State
Technician
Supply Amps: Condenser Fan Amps:
Amps:
Indoor Filter Clean?
Indoor Blower RPM
Electrical Connections Tight?
Supply Voltage (Unit O )
Compressor Amps:
S.P. Drop Over Evaporator (Dry)
Condenser Entering Air Temperature
Discharge Pressure Suction Pressure
COOLING SECTION
THERMOSTAT
Re rigerant Charge Checked?
Calibrated? Properly Set? Level?
Properly Insulated?
Suction Service Valve Caps Tight?
Voltage With Compressor Operating
Leak Checked?
Liquid Service Valve Caps Tight?
Blower interlocked with compressor?
Compressor Rotation Checked?