Lennox 12HPB Installation Instructions PDF
Summary of Content for Lennox 12HPB Installation Instructions PDF
Page 1 504,532M
06/04
2002 Lennox Industries Inc.
Dallas, Texas, USA
12HPB Outdoor Units
Lennox Merit Series 12HPB outdoor units are approved
and warranted only for installation with specially
matched indoor coils, line sets, and refrigerant control
devices as designated by Lennox. Refer to Lennox engi-
neering handbook for expansion valve (TXV) kits which
must be ordered separately.
Shipping and Packing List
1 Assembled 12HPB outdoor unit
Check unit for shipping damage. Consult last carrier imme-
diately if damage is found.
WARNING Improper installation, adjustment, alteration, service or maintenance can cause property damage, person- al injury or loss of life. Installation and service must be performed by a qualified installer or service agency.
IMPORTANT The Clean Air Act of 1990 bans the intentional vent- ing of refrigerant (CFCs and HCFCs) as of July 1, 1992. Approved methods of recovery, recycling or reclaiming must be followed. Fines and/or incarcera- tion may be levied for noncompliance.
INSTALLATION INSTRUCTIONS
12HPB Series Units HEAT PUMP UNITS 2 through 5 tons 504,532M 06/04
Supersedes 04/04
Table of Contents
12HPB Outdoor Units 1. . . . . . . . . . . . . . . . . . . . . . . . . . . Shipping & Packing List 1. . . . . . . . . . . . . . . . . . . . . . . . . General Information 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Setting the Unit 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electrical 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refrigerant Piping 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refrigerant Metering Device 10. . . . . . . . . . . . . . . . . . . . Manifold Gauge Set 10. . . . . . . . . . . . . . . . . . . . . . . . . . . Service Valves 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Leak Testing 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Evacuation 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . StartUp 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Charging 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System Operation 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Defrost System 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maintenance 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Optional Accessories 18. . . . . . . . . . . . . . . . . . . . . . . . . . StartUp and Performance Check List 18. . . . . . . . . . . .
RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE
General Information
These instructions are intended as a general guide and do
not supersede national or local codes in any way. Authori-
ties having jurisdiction should be consulted before installa-
tion.
WARNING This product and/or the indoor unit it is matched with may contain fiberglass wool.
Disturbing the insulation during installation, mainte- nance, or repair will expose you to fiberglass wool dust. Breathing this may cause lung cancer. (Fiber- glass wool is known to the State of California to cause cancer.)
Fiberglass wool may also cause respiratory, skin, and eye irritation.
To reduce exposure to this substance or for further information, consult material safety data sheets available from address shown below, or contact your supervisor.
Lennox Industries Inc.
P.O. Box 799900 Dallas, TX 753799900
Litho U.S.A.
Page 2
Unit Dimensions inches (mm)
Side View
vapor & liquid line
connections
discharge air
Side View
TOP VIEW
outdoor coil fan
compressor
inlet air
vapor line connection
2-3/4 (70)
A
electrical inlets
liquid line connection
4-3/8 (111)
6-3/8 (162)
6-3/8 (162)
Top View Base Section
4-3/8 (111)
4-3/8 (111)
4-3/8 (111)
4-3/8 (111)
4-3/8 (111)
compressor
coil drain outlets (around perimeter of base)
optional unit stand-off kit (4) (fieldinstalled)
BC
A
optional unit stand-off kit (4) (fieldinstalled)
2 (51)
3/4 (19)
optional unit stand-off kit (4) (fieldinstalled)
inlet air
inlet
air
inlet
air
Model No. A B C
12HPB24 12HPB30 in. 24-1/4 33-1/4 32-1/2
12HPB36 12HPB42 mm 616 819 826
12HPB48 12HPB60 in. 28-1/4 37 36-1/4
mm 718 940 921
Page 3
Setting the Unit
CAUTION In order to avoid injury, take proper precaution when lifting heavy objects.
CAUTION Sharp sheet metal edges can cause injury. When installing the unit, avoid accidental contact with sharp edges.
Outdoor units operate under a wide range of weather con-
ditions; therefore, several factors must be considered
when positioning the outdoor unit. The unit must be posi-
tioned to give adequate clearances for sufficient airflow
and servicing. A minimum clearance of 24 inches (610 mm)
between multiple units must be maintained. Refer to figure
1 for installation clearances.
36 (914 mm)
Installation Clearances
Figure 1
36* (914 mm)
*NOTE A service clearance of 30" (762 mm) must be main-
tained on one of the sides adjacent to the control box. Clear-
ance to one of the other three sides must be 36" (914 mm).
Clearance to one of the remaining two sides may be 12" (304
mm) and the final side may be 6" (152 mm).
36* (914 mm)
NOTE A clearance of 24" (610 mm) must be maintained between two units.
NOTE 48" (1219 mm) clearance required on top of unit. Maximum soffit overhang is 36" (914 mm).
36 (914 mm)
1 Place a sound-absorbing material, such as Isomode,
under the unit if it will be installed in a location or posi-
tion that will transmit sound or vibration to the living
area or adjacent buildings.
2 Install the unit high enough above the ground or roof to
allow adequate drainage of defrost water and prevent
ice buildup.
3 In heavy snow areas, do not locate the unit where drift-
ing will occur. The unit base should be elevated above
the depth of average snows.
NOTE Elevation of the unit may be accomplished by
constructing a frame using suitable materials. If a sup-
port frame is constructed, it must not block drain holes
in unit base.
4 When installed in areas where low ambient tempera-
tures exist, locate unit so winter prevailing winds do not
blow directly into outdoor coil.
5 Locate unit away from overhanging roof lines which
would allow water or ice to drop on, or in front of, coil or
into unit.
Slab Mounting Figure 2
When installing a unit at grade level, the top of the slab
should be high enough above the grade so that water from
higher ground will not collect around the unit. See figure 2.
Slab should have a slope tolerance away from the building
of 2 degrees or 2 inches per 5 feet (51 mm per 1524 mm).
This will prevent ice from building up under the unit during a
defrost cycle. Refer to the roof mounting section for barrier
construction if the unit must face prevailing winter winds.
Slab Mounting At Ground Level
discharge air
Mounting slab must slope away from building. ground level
structure
Figure 2
Roof Mounting Figure 3
Install the unit a minimum of 6 inches (152 mm) above the
roof surface to avoid ice buildup around the unit. Locate
the unit above a load bearing wall or area of the roof that
can adequately support the unit. Consult local codes for
rooftop applications.
Page 4
If unit coil cannot be mounted away from prevailing winter
winds, a wind barrier should be constructed. Size the barri-
er at least the same height and width as outdoor unit. Mount
barrier 24 inches (610 mm) from the sides of the unit in the
direction of prevailing winds.
wind barrier inlet air
prevailing winter winds
Rooftop Application Wind Barrier ConstrucTion
inlet air
inlet air
inlet air
Figure 3
Electrical
In the U.S.A., wiring must conform with current local codes
and the current National Electric Code (NEC). In Canada,
wiring must conform with current local codes and the current
Canadian Electrical Code (CEC).
Refer to the furnace or blower coil installation instructions
for additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
overcurrent protection size.
WARNING Unit must be grounded in accordance with national and local codes. Electric Shock Hazard. Can cause injury or death.
1 Install line voltage power supply to unit from a properly
sized disconnect switch.
2 Ground unit at unit disconnect switch or to an earth
ground.
NOTE To facilitate conduit, a hole is in the bottom of
the control box. Connect conduit to the control box us
ing a proper conduit fitting.
NOTE Units are approved for use only with copper
conductors.
24V, Class II circuit connections are made in the low
voltage junction box. Refer to figure 4 for field wiring
diagram.
NOTE A complete unit wiring diagram is located in
side the unit control box cover.
3 Install room thermostat (ordered separately) on an in-
side wall approximately in the center of the conditioned
area and 5 feet (1.5 m) from the floor. It should not be
installed on an outside wall or where it can be effected
by sunlight, drafts or vibrations.
4 Install low voltage wiring from outdoor to indoor unit and
from thermostat to indoor unit. See figures 5 and 6.
Page 5
Typical Wiring Field Wiring Diagram
Figure 4
*
*
* may be optional
R
C
W1
Y1
O
G
R
C
W1
W2
W3
G
reversing valve
12HPB and Blower Unit Thermostat Designations
(Some connections may not apply.
Refer to specific thermostat and indoor unit.)
Thermostat Indoor Unit
R
C
W1
Y1
O
Outdoor Unit
power power
common common
1st. stage aux. heat 1st. stage aux. heat
indoor blower
compressor
Figure 5
R
C
W1
Y1
O
G
R
C
W1
W2
W3
G
Outdoor Unit and Blower Unit Thermostat Designations
(with emergency heat) (Some connections may not apply.
Refer to specific thermostat and indoor unit.)
Thermostat Indoor Unit
Outdoor Unit
E
R
C
W1
Y1
O reversing valve
indoor blower
compressor
power power
common common
1st. stage aux. heat 1st. stage aux. heat
emergency heat em.
heat rly
outdoor tstat
Figure 6
Page 6
Refrigerant Piping
Field refrigerant piping consists of liquid and vapor lines
from the outdoor unit (sweat connections) to the indoor coil
(flare or sweat connections).
Use Lennox L15 (sweat, non-flare) series line sets as
shown in table 1 or use field-fabricated refrigerant lines.
Refer to Refrigerant Piping Guide (Corp. 9351L9) for prop-
er size, type, and application of fieldfabricated lines. Valve
sizes are also listed in table 1.
Table 1 Refrigerant Line Sets
Valve Size Connections
Recommended Line Set
Model Liquid Line
Vapor Line*
Liquid Line
Vapor Line
L15 Line Sets
24 30
3/8" (9.5 mm)
3/4" (19 mm)
3/8" (9.5 mm)
3/4" (19 mm)
L1541 15 ft. 50 ft.
(4.6 m 15 m)
36 42 48
3/8" (9.5 mm)
7/8" (22.2 mm)
3/8" (9.5 mm)
7/8" (22.2 mm)
L1565 15 ft. 50 ft.
(4.6 m 15 m)
60 3/8"
(9.5 mm) 11/8" (28.5 mm)
3/8" (9.5 mm)
11/8" (28.5 mm)
Field Fabricated
NOTE Units are designed for line sets of up to fifty feet (15
m). For applications longer than fifty feet, consult the Len-
nox Refrigerant Piping Guide (Corp. 9351L9). Select line
set diameters from table 1 to ensure that oil returns to the
compressor.
Installing Refrigerant Line
During the installation of any heat pump or a/c system, it is
important to properly isolate the refrigerant lines to prevent
unnecessary vibration. Line set contact with the structure
(wall, ceiling or floor) causes some objectionable noise
when vibration is translated into sound. As a result, more
energy or vibration can be expected. Closer attention to
line set isolation must be observed.
Following are some points to consider when placing and
installing a highefficiency outdoor unit:
1- Placement Be aware some localities are adopting
sound ordinances based on how noisy the unit is from
the adjacent property not at the original installation.
Install the unit as far as possible from the property line.
When possible, do not install the unit directly outside a
window. Glass has a very high level of sound transmis-
sion.
2- Line Set Isolation The following illustrations demon-
strate procedures which ensure proper refrigerant line
set isolation. Figure 7 shows how to install line sets on
vertical runs. Figure 8 shows how to install line sets on
horizontal runs. Figure 9 shows how to make a transition
from horizontal to vertical. Finally, figure 10 shows how
to place the outdoor unit and line set.
Page 7
Installing Vertical Runs of Refrigerant Piping (new construction shown)
PVC Pipe Fiberglass Insulation
Caulk
Outside Wall
Vapor Line (wrapped with Armaflex)
Liquid Line
IMPORTANT - Refrigerant lines must not contact
structure.
Outside Wall
Inside Wall
Liquid LineVapor Line IMPORTANT - Refrigerant lines must not contact wall.
Wood Block Between Studs
Strap
Sleeve
Wood Block
Strap
Sleeve
Wire Tie
Wire Tie
Wire Tie
NOTE - Similar installation practices should be used if line set is to be installed on exterior of outside wall.
Figure 7
Page 8
Installing Horizontal Runs of Refrigerant Piping
8 feet
8 feet
Metal Sleeve
Strapping Material (around vapor line only)
Tape or Wire Tie
Wire Tie (around vapor line only)
Floor Joist or Roof Rafter
Tape or Wire Tie
Strap the vapor line to the joist or rafter at 8 ft. intervals then strap the liquid line to the vapor line.
To hang line set from joist or rafter, use either metal strapping material or anchored heavy nylon wire ties.
Floor Joist or Roof Rafter
Figure 8
Page 9
Transitioning From Vertical To Horizontal Runs of Refrigerant Piping
Liquid Line
Vapor Line Wrapped in
Armaflex
Strap Liquid Line To Vapor Line
Metal Sleeve
Anchored Heavy Nylon Wire Tie
Automotive Muffler-Type
Hanger
Wall Stud
Wall Stud
Liquid Line
Vapor Line Wrapped in
Armaflex
Strap Liquid Line To Vapor Line
Metal Sleeve
Figure 9
Outside Unit Placement and Installation
Install unit away from windows .
Two 90 elbows installed in line set will reduce line set vibration.
Figure 10
Page 10
Brazing Connection Procedure
1 Cut ends of the refrigerant lines square (free from nicks
or dents). Debur the ends. The pipe must remain
round, do not pinch end of the line.
2 Before making line set connections, use dry nitrogen to
purge the refrigerant piping. This will help to prevent
oxidation and the introduction of moisture into the sys-
tem.
3 Use silver alloy brazing rods (5 or 6 percent minimum
silver alloy for coppertocopper brazing or 45 percent
silver alloy for coppertobrass or coppertosteel braz-
ing) which are rated for use with HCFC22 refrigerant.
Wrap a wet cloth around the valve body and the copper
tube stub. Braze the line set to the service valve.
4 Wrap a wet cloth around the valve body and copper
tube stub to protect it from heat damage during braz-
ing. Wrap another wet cloth underneath the valve body
to protect the base paint.
NOTE The tube end must stay bottomed in the fitting
during final assembly to ensure proper seating, sealing
and rigidity.
5 Install a fieldprovided thermal expansion valve (ap-
proved for use with HCFC22 refrigerant) in the liquid
line at the indoor coil.
Refrigerant Metering Device
12HPB units are used in check expansion valve systems
only. See the Lennox Engineering Handbook for approved
TXV match-ups and application information.
Check expansion valves equipped with Chatleff fittings
are available from Lennox. Refer to the Engineering
Handbook for applicable check expansion valves for use
with specific match-ups. See table 2 for applicable check
expansion valve kits.
If you install a check expansion valve with an indoor
coil that includes a fixed orifice, remove the orifice be-
fore the check expansion valve is installed.
IMPORTANT Failure to remove RFC orifice when installing an ex- pansion valve on the indoor coil will result in improp- er operation and damage to the system.
Table 2
Indoor Check And Expansion Valve Kits
Model Kit Number
12HPB24 12HPB30 12HPB36
LB85759F
12HPB42 12HPB48 12HPB60
LB85759G
See figure 11 for installation of the check expansion valve.
Metering Device Installation
expansion
valve
oring
oring
strainer
liquid line
stub
distributor
Figure 11
Manifold Gauge Set
When checking the unit charge, use a manifold gauge set
that is equipped with low loss" hoses. Do not use a man-
ifold gauge set with anything other than a low loss" hose.
See figure 12 for manifold gauge connections.
Page 11
12HPB Manifold Gauge Connections (Cooling Cycle)
outdoor coil
defrost thermostat
expansion/ check valve
biflow filter / drier
to HCFC22
drum
low pressure
high pressure
compressor
reversing valve
vapor line
valve
muffler
Note Arrows indicate direction of the refrigerant flow.
vapor service
port
expansion/check valve
Indoor Unit
Outdoor Unit
liquid line service
port
GAUGE MANIFOLD
distributor
indoor coil
Figure 12
Service Valves
The liquid line and vapor line service valves (figures 13 and
14) and and gauge ports are used for leak testing, evacuat-
ing, charging and checking charge. See table 3 for torque
requirements.
Each valve is equipped with a service port which has a fac-
toryinstalled Schrader valve. A service port cap protects
the Schrader valve from contamination and serves as the
primary leak seal.
Table 3 Torque Requirements
Part Recommended Torque
Service valve cap 8 ft. lb. 11 NM
Sheet metal screws 16 in. lb. 2 NM
Machine screws #10 28 in. lb. 3 NM
Compressor bolts 90 in. lb. 10 NM
Gauge port seal cap 8 ft. lb. 11 NM
To Access Schrader Port:
1 Remove service port cap with an adjustable wrench.
2 Connect gauge to the service port.
3 When testing is completed, replace service port cap. Tighten finger tight, then an additional 1/6 turn.
To Open Service Valve:
1 Remove stem cap with an adjustable wrench.
2 Use a service wrench with a hex head extension to back the stem out counterclockwise as far as it will go.
NOTE Use a 3/16" hex head extension for liquid line sizes or a 5/16" extension for vapor line sizes.
3 Replace stem cap. Tighten finger tight, then tighten an additional 1/6 turn.
To Close Service Valve:
1 Remove stem cap with an adjustable wrench.
2 Use a service wrench with a hex head extension to turn the stem clockwise to seat the valve. Tighten firmly.
NOTE Use a 3/16" hex head extension for liquid line sizes or a 5/16" extension for vapor line sizes.
3 Replace the stem cap. Tighten finger tight, then tighten an additional 1/6 turn.
Vapor Line (BallType) Service Valve Vapor line service valves function the same way as the oth-
er valves, the difference is in the construction. These
valves are not rebuildable. If a valve has failed, you must
replace it. A ball valve valve is illustrated in figure 14.
The ball valve is equipped with a service port with a factory
installed Schrader valve. A service port cap protects the
Schrader valve from contamination and assures a leak
free seal.
Page 12
Service Valve (Valve Closed)
Schrader valve open to line set when valve is
closed (front seated)
service port
service port cap
stem cap
insert hex wrench here
(valve front seated)
to outdoor coil
to indoor coil
Service Valve (Valve Open)
Schrader valve
service port
service port cap
insert hex wrench here
to indoor coil
to outdoor coil
stem cap
Figure 13
Ball Valve (Valve Open)
Schrader valve
service port
service port cap
stem cap
stem
Use Adjustable Wrench To open: rotate Stem Counter-clockwise 90.
To close: rotate Stem Clockwise 90.
ball (shown open)
to outdoor coil
to indoor coil
Figure 14
Leak Testing
After the line set has been connected to the indoor and
outdoor units, check the line set connections and indoor
unit for leaks.
WARNING Danger of fire. Bleeding the refrigerant charge from only the high side may re- sult in the low side shell and suction tubing being pressurized. Appplication of a brazing torch while pressurized may result in ignition of the refrigerant and oil mixture check the high and low pressures before unbrazing.
WARNING Refrigerant can be harmful if it is inhaled. Refrigerant must be used and recovered responsibly.
Failure to follow this warning may result in personal injury or death.
WARNING Danger of explosion: Can cause equip- ment damage, injury or death. Never use oxygen to pressurize a refrigera- tion or air conditioning system. Oxygen will explode on contact with oil and could cause personal injury.
WARNING Danger of explosion: Can cause equipment damage, injury or death. When using a high pressure gas such as dry nitrogen to pressurize a refrigeration or air conditioning system, use a regulator that can control the pressure down to 1 or 2 psig (6.9 to 13.8 kPa).
Using an Electronic Leak Detector or Halide 1 Connect a cylinder of HCFC-22 to the center port of the
manifold gauge set.
2 With both manifold valves closed, open the valve on
the HCFC-22 cylinder (vapor only).
3 Open the high pressure side of the manifold to allow
the HCFC-22 into the line set and indoor unit. Weigh in
a trace amount of HCFC-22. [A trace amount is a maxi-
mum of 2 ounces (57 g) or 3 pounds (31 kPa) pres-
sure.] Close the valve on the HCFC-22 cylinder and the
valve on the high pressure side of the manifold gauge
set. Disconnect the HCFC-22 cylinder.
4 Connect a cylinder of nitrogen with a pressure regulat-
ing valve to the center port of the manifold gauge set.
5 Connect the manifold gauge set high pressure hose to
the vapor valve service port. (Normally, the high pres-
sure hose is connected to the liquid line port; however,
connecting it to the vapor port better protects the man-
ifold gauge set from high pressure damage.)
6 Adjust the nitrogen pressure to 150 psig (1034 kPa).
Open the valve on the high side of the manifold gauge
set which will pressurize line set and indoor unit.
Page 13
7 After a few minutes, open a refrigerant port to ensure
the refrigerant you added is adequate to be detected.
(Amounts of refrigerant will vary with line lengths.)
Check all joints for leaks. Purge nitrogen and HCFC-22
mixture. Correct any leaks and recheck.
Evacuation
Evacuating the system of noncondensables is critical for
proper operation of the unit. Noncondensables are defined
as any gas that will not condense under temperatures and
pressures present during operation of an air conditioning
system. Noncondensables and water vapor combine with
refrigerant to produce substances that corrode copper pip-
ing and compressor parts.
IMPORTANT Use a thermocouple or thermistor electronic vacuum gauge that is calibrated in microns. Use an instrument that reads from 50 microns to at least 10,000 microns.
1 Connect manifold gauge set to the service valve ports :
low pressure gauge to vapor line service valve high pressure gauge to liquid line service valve
2 Connect micron gauge.
3 Connect the vacuum pump (with vacuum gauge) to the
center port of the manifold gauge set.
4 Open both manifold valves and start vacuum pump.
5 Evacuate the line set and indoor unit to an absolute
pressure of 23,000 microns (29.01 inches of mercu-
ry). During the early stages of evacuation, it is desir-
able to close the manifold gauge valve at least once to
determine if there is a rapid rise in absolute pressure.
A rapid rise in pressure indicates a relatively large leak.
If this occurs, repeat the leak testing procedure.
NOTE The term absolute pressure means the total
actual pressure within a given volume or system,
above the absolute zero of pressure. Absolute pres-
sure in a vacuum is equal to atmospheric pressure mi-
nus vacuum pressure.
6 When the absolute pressure reaches 23,000 microns
(29.01 inches of mercury), close the manifold gauge
valves, turn off the vacuum pump and disconnect the
manifold gauge center port hose from vacuum pump.
Attach the manifold center port hose to a nitrogen cylin-
der with pressure regulator set to 150 psig (1034 kPa)
and purge the hose. Open the manifold gauge valves
to break the vacuum in the line set and indoor unit.
Close the manifold gauge valves.
CAUTION Danger of Equipment Damage. Avoid deep vacuum operation. Do not use compres- sors to evacuate a system. Extremely low vacuums can cause internal arcing and compressor failure. Damage caused by deep vacuum operation will void warranty.
7 Shut off the nitrogen cylinder and remove the manifold
gauge hose from the cylinder. Open the manifold
gauge valves to release the nitrogen from the line set
and indoor unit.
8 Reconnect the manifold gauge to the vacuum pump,
turn the pump on, and continue to evacuate the line set
and indoor unit until the absolute pressure does not
rise above 500 microns (29.9 inches of mercury) within
a 20minute period after shutting off the vacuum pump
and closing the manifold gauge valves.
9 When the absolute pressure requirement above has
been met, disconnect the manifold hose from the vacu-
um pump and connect it to an upright cylinder of
HCFC-22 refrigerant. Open the manifold gauge valves
to break the vacuum from 1 to 2 psig positive pressure in
the line set and indoor unit. Close manifold gauge
valves and shut off the HCFC-22 cylinder and remove
the manifold gauge set.
StartUp
IMPORTANT If unit is equipped with crankcase heater, it should be energized 24 hours before unit startup to prevent compressor damage as a result of slugging.
1 Rotate the fan to check for frozen bearings or binding.
2 Inspect all factory and field-installed wiring for loose
connections.
3 After evacuation is complete, open the liquid line and
vapor line service valves to release the refrigerant
charge (contained in outdoor unit) into the system.
4 Replace the stem caps and secure finger tight, then
tighten an additional one-sixth (1/6) of a turn.
5 Check voltage supply at the disconnect switch. The
voltage must be within the range listed on the units
nameplate. If not, do not start the equipment until you
Page 14
have consulted the power company and the voltage
condition has been corrected.
6 Set the thermostat for a cooling demand. Turn on pow-
er to the indoor blower and close the outdoor unit dis-
connect switch to start the unit.
7 Recheck voltage while the unit is running. Power must
be within range shown on the nameplate.
Charging
The unit is factory charged with the amount of HCFC-22 re-
frigerant indicated on the unit rating plate. This charge is
based on a matching indoor coil and outdoor coil with a 15
foot (4.6 m) line set. For varying lengths of line set, refer to
table 4 for refrigerant charge adjustment.
Table 4
Liquid Line Set Diameter
Oz. per 5 ft. (g per 1.5 m) adjust from 15 ft. (4.6 m) line set*
3/8 in. (9.5 mm) 3 ounce per 5 ft. (85g per 1.5 m)
*If line length is greater than 15 ft. (4.6 m), add this amount. If line length is less than 15 ft. (4.6 m), subtract this amount.
The outdoor unit should be charged during warm weather.
However, applications arise in which charging must occur
in the colder months. The method of charging is deter-
mined by the units refrigerant metering device and the
outdoor ambient temperature.
Measure the liquid line temperature and the outdoor ambi-
ent temperature as outlined below:
1 Close manifold gauge set valves. Connect the man-
ifold gauge set to the service valves.
low pressure gauge to vapor valve service port
high pressure gauge to liquid valve service port
Connect the center manifold hose to an upright cylin-
der of HCFC-22.
2 Set the room thermostat to call for heat. This will create
the necessary load for properly charging the system in
the cooling cycle.
3 Use a digital thermometer to record the outdoor ambi-
ent temperature.
4 When the heating demand has been satisfied, switch
the thermostat to cooling mode with a set point of 68F
(20C). When pressures have stabilized, use a digital
thermometer to record the liquid line temperature.
5 The outdoor temperature will determine which charg-
ing method to use. Proceed with the appropriate charg-
ing procedure.
Weighing in the Charge TXV Systems
Outdoor Temp < 65F (18C)
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, the refrigerant charge should be
weighed into the unit. Do this after any leaks have been re-
paired.
1 Recover the refrigerant from the unit.
2 Conduct a leak check, then evacuate as previously
outlined.
3 Weigh in the unit nameplate charge.
If weighing facilities are not available or if you are charging
the unit during warm weather, follow one of the other proce-
dures outlined below.
Subcooling Method
Outdoor Temp. < 65F (18C)
When the outdoor ambient temperature is below 65F
(18C), use the subcooling method to charge the unit. It
may be necessary to restrict the air flow through the out-
door coil to achieve pressures in the 200250 psig
(13791724 kPa) range. These higher pressures are nec-
essary for checking the charge. Block equal sections of air
intake panels and move obstructions sideways until the liq-
uid pressure is in the 200250 psig (13791724 kPa) range.
See figure 15.
Blocking Outdoor Coil
cardboard or plastic sheet
Outdoor coil should be blocked one side
at a time with cardboard or plastic sheet until proper
testing pressures are reached.
Figure 15
1 With the manifold gauge hose still on the liquid service
port and the units pressure stabilized, use a digital
thermometer to record the liquid line temperature.
2 At the same time, record the liquid line pressure reading.
3 Use a temperature/pressure chart for HCFC-22 to de-
termine the saturation temperature for the liquid line
pressure reading.
4 Subtract the liquid line temperature from the saturation
temperature (according to the chart) to determine sub-
cooling. (Saturation temperature Liquid line tem-
perature = Subcooling)
5 Compare the subcooling value with those in table 5. If
subcooling is greater than shown, recover some refrig-
erant. If subcooling is less than shown, add some re-
frigerant.
Table 5 Subcooling Values
Model Subcooling Temp. F (C)
12HPB24 11 (6.1)
12HPB30 5 (2.8)
12HPB36 3 (1.7)
12HPB42 4 (2.2)
12HPB48 4 (2.2)
12HPB60 6 (3.3)
Page 15
Charging Using Normal Operating Pressures
and the Approach Method
Outdoor Temp. > 65F (18C)
The following procedure is intended as a general guide and
is for use on expansion valve systems only. For best results,
indoor temperature should be 70F (21C) to 80F (26C).
Monitor system pressures while charging.
1 Record outdoor ambient temperature using a digital
thermometer.
2 Attach high pressure gauge set and operate unit for
several minutes to allow system pressures to stabilize.
3 Compare stabilized pressures with those provided in
table 7, Normal Operating Pressures." Minor varia-
tions in these pressures may be expected due to differ-
ences in installations. Significant differences could
mean that the system is not properly charged or that a
problem exists with some component in the system.
Pressures higher than those listed indicate that the
system is overcharged. Pressures lower than those
listed indicate that the system is undercharged. Verify
adjusted charge using the approach method.
Approach Method
4 Use the same digital thermometer used to check out-
door ambient temperature to check liquid line tempera-
ture. Verify the unit charge using the approach method.
5 The difference between the ambient and liquid temper-
atures should match values given in table 6. If the val-
ues dont agree with the those in table 6, add refriger-
ant to lower the approach temperature or recover re-
frigerant from the system to increase the approach
temperature.
Table 6 Approach Values
Model Liquid Temp. Minus Ambient Temp.
F (C)
12HPB24 6 (3.3)
12HPB30 11 (6.1)
12HPB36 12 (6.7)
12HPB42 10 (5.6)
12HPB48 9 (5)
12HPB60 8 (4.4)
NOTE For best results, the same thermometer should be used to check both outdoor ambient and liquid temperatures.
Table 7 Normal Operating Pressures
Outdoor Coil 12HPB24 12HPB30 12HPB36 12HPB42 12HPB48 12HPB60
Air Entering Temp. F (C)
liq. +10
PSIG
vap. +5
PSIG
liq. +10
PSIG
vap. +5
PSIG
liq. +10
PSIG
vap. +5
PSIG
liq. +10
PSIG
vap. +5
PSIG
liq. +10
PSIG
vap. +5
PSIG
liq. +10
PSIG
vap. +5
PSIG
65 (183.) 144 78 140 76 152 74 152 75 146 75 146 73
75 (23.9) 170 79 164 77 178 76 179 76 171 77 175 74
85 (29.4) 199 80 194 78 208 77 210 77 198 78 206 75
95 (35) 228 81 224 79 238 78 241 78 229 79 237 76
105 (40.6) 261 82 259 80 275 81 278 79 268 81 275 77
NOTE Typical pressures only. Indoor evaporator match up, indoor air quantity, and evaporator load will cause the pressures to vary.
Page 16
IMPORTANT Use table 7 as a general guide when performing maintenance checks. This is not a procedure for charging the unit (Refer to Charging/Checking Charge section). Minor variations in these pressures may be expected due to differences in installations. Significant differences could mean that the system is not properly charged or that a problem exists with some component in the system.
System Operation
The outdoor unit and indoor blower cycle on demand from
the room thermostat. When the thermostat blower switch is
in the ON position, the indoor blower operates continuously.
Filter Drier
The unit is equipped with a biflow filter drier. See figure 12.
If replacement is necessary, order another of like design.
Crankcase Heater
IMPORTANT If unit is equipped with crankcase heater, it should be energized 24 hours before unit startup to prevent compressor damage as a result of slugging.
Emergency Heat Function (Room Thermostat)
An emergency heat function is designed into some room
thermostats. This feature is applicable when isolation of
outdoor unit is required or when auxiliary electric heat is
staged by outdoor thermostats. When the room thermostat
is placed in the emergency heat position, the outdoor unit
control circuit is isolated from power and field-provided re-
lays bypass the outdoor thermostats. An amber indicating
light simultaneously comes on to remind the homeowner
that he is operating in the emergency heat mode.
Emergency heat is usually used during an outdoor shut-
down, but it should also be used following a power outage if
power has been off for over an hour and the outdoor tem-
perature is below 50F (10C). System should be left in the
emergency heat mode at least six hours to allow the crank-
case heater sufficient time to prevent compressor slug-
ging.
Defrost System
The 12HPB defrost system includes two components: a
defrost thermostat and a defrost control.
Defrost Thermostat
The defrost thermostat is located on the liquid line between
the check/expansion valve and the distributor. When de-
frost thermostat senses 42F (5.5C) or cooler, the thermo-
stat 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 includes the combined func-
tions of a time/temperature defrost control, defrost relay,
diagnostic LEDs and terminal strip for field wiring connec-
tions. See figure 16.
The control provides automatic switching from normal
heating operation to defrost mode and back. During com-
pressor cycle (call for defrost), the control accumulates
compressor run times at 30, 60, or 90 minute fieldadjust-
able intervals. If the defrost thermostat is closed when the
selected compressor run time interval ends, the defrost
relay is energized and defrost begins.
Page 17
12HPB Defrost Control Board
24V terminal strip
High Pressure Switch Safety Circuit Connections
S4
connection for optional
high pressure switch
defrost interval
timing pins
high pressure
switch
diagnostic LEDs
Figure 16
NOTE To add pressure switch, remove factory
installed jumper
Defrost Control Timing Pins
Each timing pin selection provides a different accumu-
lated compressor run time period during one thermostat
run cycle. This time period must occur before a defrost
cycle is initiated. The defrost interval can be adjusted to
30 (T1), 60 (T2), or 90 (T3) minutes. See figure 16. The
defrost timing jumper is factoryinstalled to provide a
60minute defrost interval. If the timing selector jumper is
not in place, the control defaults to a 90minute defrost
interval. The maximum defrost period is 14 minutes and
cannot be adjusted.
A TEST option is provided for troubleshooting. The TEST
mode may be started any time the unit is in the heating
mode and the defrost thermostat is closed or jump-
ered. If the jumper is in the TEST position at power-up, the
control will ignore the test pins. When the jumper is placed
across the TEST pins for two seconds, the control will enter
the defrost mode. If the jumper is removed before an addi-
tional 5second period has elapsed (7 seconds total), the
unit will remain in defrost mode until the defrost thermostat
opens or 14 minutes have passed. If the jumper is not re-
moved until after the additional 5second period has
elapsed, the defrost will terminate and the test option will
not function again until the jumper is removed and reap-
plied.
Pressure Switch Circuit
The defrost control incorporates a pressure switch circuit
that allows the application of an optional high pressure
switch. See figure 16. During a demand cycle, the defrost
control will lock out the unit if the optional high pressure
switch opens. The diagnostic LEDs will display a pattern for
an open high pressure switch. See table 8. The unit will re-
main locked out until the switch resets or is reset.
Remove the factory-installed jumper before connecting the
optional high pressure switch to the control board.
NOTE If not using a pressure switch, the factory-installed
jumper wire must be connected.
Diagnostic LEDs
The defrost board uses two LEDs for diagnostics. The LEDs
flash a specific sequence according to the condition.
Table 8 Defrost Control Board Diagnostic LED
Mode LED 1 LED 2
Normal operation / power to board
Synchronized Flash with LED 2
Synchronized Flash with LED 1
Board failure or no power Off Off
Board failure On On
Pressure switch open Flash On
Page 18
Maintenance
WARNING Electric shock hazard. Can cause injury or death. Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at discon- nect switch(es). Unit may have multiple power supplies.
Maintenance and service must be performed by a qualified installer or service agency. At the beginning of each cooling or heating season, the system should be checked as fol- lows:
Outdoor Unit
1 Clean and inspect the outdoor coil. The coil may be flushed with a water hose. Ensure the power is turned off before you clean the coil.
2 Outdoor unit fan motor is pre-lubricated and sealed. No further lubrication is needed.
3 Visually inspect all connecting lines, joints and coils for evidence of oil leaks.
4 Check wiring for loose connections.
5 Check for correct voltage at unit (unit operating).
6 Check amp draw on outdoor fan motor. Unit nameplate__________Actual__________.
7 - Inspect drain holes in coil compartment base and clean if necessary.
NOTE If owner complains of insufficient cooling, the unit should be gauged and refrigerant charge checked. Refer to section on refrigerant charging in this instruction.
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.
Indoor Unit
1 Clean or change filters.
2 - Lennox blower motors are prelubricated and permanent- ly sealed. No more lubrication is needed.
3 Adjust blower speed for cooling. Measure the pressure drop over the coil to determine the correct blower CFM. Refer to the unit information service manual for pressure drop tables and procedure.
4 Belt Drive Blowers Check belt for wear and proper tension.
5 Check all wiring for loose connections.
6 Check for correct voltage at unit. (blower operating)
7 Check amp draw on blower motor. Motor nameplate__________Actual__________.
Optional Accessories
Refer to the Engineering Handbook for optional accesso- ries that may apply to this unit. The following may or may not apply:
Loss of Charge Kit
High Pressure Switch Kit
Compressor Monitor
Compressor Crankcase Heater
Hail Guards
Mounting Bases
Standoff Kit
Sound Cover
Low Ambient Kit
Monitor Kit
Mild Weather Kit
StartUp and Performance Check List
Startup and Performance Check List
Job Name
Job Location
Installer
Unit Model No.
Nameplate Voltage
Rated Load Ampacity
Maximum Fuse or Circuit Breaker
Refrigerant Lines:
Service Valves Fully Opened?
Outdoor Fan Checked?
Job No.
City
City
Serial No.
Date
State
State
Service Technician
Compressor Outdoor Fan
Indoor Filter Clean?Electrical Connections Tight? Supply Voltage (Unit Off)
Vapor Pressure
Thermostat
Refrigerant Charge Checked?
Calibrated? Properly Set? Level?
Properly Insulated?
Voltage
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