Lennox HPXA12, HPXA12−018, HPXA12−024, HPXA12−030, HPXA12−036 Installation Instructions Manual
...
®
INSTALLATION
2002 Lennox Industries Inc.
Dallas, Texas
HPXA12 Outdoor Unit
HPXA12 Elite® outdoor units use R410A, which is an ozone
friendly HFC refrigerant. This unit must be installed with a
matching indoor blower coil and line set as outlined in the
Lennox Engineering Handbook. HPXA12 outdoor units are
designed for use in expansion valve systems only. They
are not designed to be used with other refrigerant flow control devices. An expansion valve approved for use with
R410A must be ordered separately and must be installed
prior to operating the unit.
INSTRUCTIONS
HPXA12 SERIES UNITS
HEAT PUMP UNITS
504,777M
05/04
Supersedes 02/04
Table of Contents
HPXA12 Outdoor Unit 1. . . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping & Packing List 1. . . . . . . . . . . . . . . . . . . . . . . . .
General Information 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Unit 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Refrigerant Piping 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing Existing Line Set & Indoor Coil 6. . . . . . . . . . .
Refrigerant Metering Device 7. . . . . . . . . . . . . . . . . . . . .
Manifold Gauge Set 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Valves 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak Testing 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Evacuation 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start−Up 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Charging 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Operation 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defrost System 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optional Accessories 18. . . . . . . . . . . . . . . . . . . . . . . . . .
Homeowner Information 18. . . . . . . . . . . . . . . . . . . . . . . .
HPXA12 Check List 20. . . . . . . . . . . . . . . . . . . . . . . . . . . .
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
Litho U.S.A.
IMPORTANT
This unit must be matched with an indoor coil as
specified in Lennox’ Engineering Handbook. Coils
previously charged with R22 must be flushed
Shipping & Packing List
1 − Assembled HPXA12 outdoor unit
Check the unit components for shipping damage. If you find
any damage, immediately contact the last carrier.
IMPORTANT
The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFC’s, HFC’s, and HCFC’s) as of
July 1, 1992. Approved methods of recovery, recycling or reclaiming must be followed. Fines and/or incarceration may be levied for noncompliance.
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal injury or loss of life. Installation and service must
be performed by a qualified installer or service
agency.
05/04
*2P0504*
General Information
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
WARNING
This product and/or the indoor unit it is matched with
may contain fiberglass wool.
Disturbing the insulation during installation, maintenance, or repair will expose you to fiberglass wool
dust. Breathing this may cause lung cancer. (Fiberglass 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 75379−9900
504,777M
*P504777M*
Unit Dimensions − inches (mm)
HPXA12−048
INLET AIR
INLET
AIR
INLET AIR
Top View
A
INLET
AIR
VAPOR LINE
CONNECTION
LIQUID LINE
CONNECTION
Model No. A B C
HPXA12−018
HPXA12−024
in. 24-1/4 33−1/4 32-1/2
HPXA12−030
HPXA12−036
HPXA12−042
HPXA12−048
HPXA12−060
mm 616 845 826
in. 28-1/4 37−1/4 36-1/2
mm 718 946 927
A
OUTDOOR
COIL FAN
DISCHARGE AIR
Side View
3/4
(19)
BC
ELECTRICAL
INLETS
2 (51)
COMPRESSOR
LIQUID LINE
CONNECTION
OPTIONAL UNIT
STAND-OFF KIT (4)
(Field Installed)
VAPOR &
2-3/4 (70)
Side View
Page 2
Setting the Unit
CAUTION
In order to avoid injury, take proper precaution when
lifting heavy objects.
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.
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 conditions; therefore, several factors must be considered
when positioning the outdoor unit. Unit must be positioned
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.
Installation Clearances
as
noted
as
noted
as
noted
Slab Mounting−Figure 2
When installing the 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.
The 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 build-up under the unit during a defrost cycle. Refer to roof mounting section for barrier construction if the unit must face prevailing winter winds.
Slab Mounting At Ground Level
STRUCTURE
DISCHARGE AIR
as
noted
*NOTE − A service clearance of 30" (762 mm) must be maintained on one of the sides adjacent to the control box. Clearance to one of the other three sides must be 36" (914 mm).
Clearance to one of the remaining two sides may be 12" (305
mm) and the final side may be 6" (152 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).
Figure 1
1 - Place a sound-absorbing material, such as Isomode,
under the unit if it will be installed in a location or position that will transmit sound or vibration to the living
area or adjacent buildings.
2 - Mount unit high enough above ground or roof to allow
adequate drainage of defrost water and prevent ice
build-up.
3 - In heavy snow areas, do not locate unit where drifting
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 support frame is constructed, it must not block drain holes
in unit base.
MOUNTING SLAB MUST SLOPE
AWAY FROM BUILDING.
GROUND LEVEL
Figure 2
Roof Mounting−Figure 3
Install unit a minimum of 6 inches (152 mm) above the roof
surface to avoid ice build−up 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.
Rooftop Application
Wind Barrier Construction
PREVAILING WINTER WINDS
WIND BARRIER
INLET AIR
INLET AIR
INLET AIR
INLET AIR
Figure 3
Page 3
If unit coil cannot be mounted away from prevailing winter
winds, construct a wind barrier. Size barrier at least the
same height and width as the outdoor unit. Mount barrier 24
inches (610 mm) from the sides of the unit in the direction of
prevailing winds.
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.
Refer to figure 4 for high voltage 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.
NOTE − 24V, Class II circuit connections are made in
the low voltage junction box.
Typical Field Wiring Diagram
Figure 4
Page 4
HPXA12 and Blower Unit
Thermostat Designations
(Some connections may not apply.
Refer to specific thermostat and indoor unit.)
Thermostat
Indoor
Unit
R
C
W1
G
O
Y1
power
common common
1st. stage aux. heat
indoor blower
reversing valve
compressor
R
C
W1
W2
W3
G
1st. stage aux. heat
power
Outdoor
Unit
R
C
W1
O
Y1
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, nonflare) series line sets as shown in table 1 or use field-fabricated refrigerant lines. Refer to Refrigerant Piping Guide
(Corp. 9351−L9) for proper size, type, and application of
field−fabricated lines. Valve sizes are also listed in table 1.
Plumbing Connections
HPXA12 Matched with New Indoor Coil and Line Set
If you are replacing an existing coil that is equipped
with a liquid line functioning as a metering orifice, replace the liquid line prior to installing the HPXA12 unit.
See table 1.
Table 1
Refrigerant Line Sets
Model
Valve Field Size
Connections
Liquid
Line
Vapor
Line
Recommended Line Set
Liquid
Line
Vapor
Line
L15
Line Sets
Figure 5
Outdoor Unit and Blower Unit
Thermostat Designations
(with auxiliary heat)
(Some connections may not apply.
Refer to specific thermostat and indoor unit.)
Thermostat
R
C
emergency heat
E
W1
1st. stage aux. heat
indoor blower
G
reversing valve
O
compressor
Y1
Indoor
Unit
power
common common
R
C
em.
heat rly
W1
1st. stage aux. heat
W2
W3
G
Outdoor
power
outdoor t’stat
Unit
R
C
W1
O
Y1
Figure 6
Refrigerant Piping
If the HPXA12 unit is being installed with a new indoor coil
and line set, the plumbing connections should be made as
outlined in this section. If an existing line set and/or indoor
coil is going to be used to complete the HPXA12 system,
refer to the following section that includes flushing procedures.
−18
−24
−30
−36
−42
−48
−60
3/8 in.
(10 mm)
3/8 in.
(10 mm)
3/8 in.
(10 mm)
3/4 in.
(19 mm)
7/8 in.
(22 mm)
1−1/8 in.
(29 mm)
3/8 in.
(10 mm)
3/8 in.
(10 mm)
3/8 in.
(10 mm)
3/4 in.
(19 mm)
7/8 in.
(22 mm)
1−1/8 in.
(29 mm)
L15−41
15 ft. − 50 ft.
(4.6 m − 15 m)
L15−65
15 ft. − 50 ft.
(4.6 m − 15 m)
Field
Fabricated
NOTE − Units are designed for line sets of up to fifty feet
(15m).
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 high−efficiency 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 transmission.
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 5
Refrigerant Line Sets
How To Install Vertical Runs
(new construction shown)
NOTE - Similar installation practices should be used if
line set is to be installed on exterior of outside wall.
Outside Wall
Wood Block
Between Studs
Liquid Line
Vapor Line
(wrapped with Armaflex)
Outside Wall
IMPORTANT - Refrigerant
lines must not contact wall.
Liquid LineVapor Line
Wire Tie
Inside Wall
Strap
Sleeve
Wire Tie
Wood Block
Wire Tie
Caulk
PVC Pipe
Fiberglass
Insulation
IMPORTANT - Refrigerant
lines must not contact
structure.
Strap
Sleeve
Figure 7
Page 6
Installing Horizontal Runs
To hang line set from joist or rafter,
use either metal strapping material
or anchored heavy nylon wire ties.
Floor Joist or
Roof Rafter
Refrigerant Line Sets:
Wire Tie
(around vapor line only)
8 feet
Tape or Wire Tie
8 feet
Strapping Material (around vapor line only)
Tape or Wire Tie
Metal Sleeve
Floor Joist or Roof Rafter
Strap the vapor line to the joist or rafter at 8 ft.
intervals then strap the liquid line to the vapor line.
Figure 8
Page 7
Refrigerant Line Sets:
Transition From Vertical To Horizontal
Anchored Heavy
Nylon Wire Tie
Wall
Stud
Metal
Sleeve
Vapor Line
Wrapped in
Armaflex
Strap Liquid Line
To Vapor Line
Liquid Line
Figure 9
Automotive
Muffler-Type
Hanger
Wall
Stud
Metal
Sleeve
Strap Liquid Line
To Vapor Line
Liquid Line
Vapor Line
Wrapped in
Armaflex
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 8
WARNING
Polyol ester (POE) oils used with R410A refrigerant
absorb moisture very quickly. It is very important
that the refrigerant system be kept closed as much
as possible. DO NOT remove line set caps or service valve stub caps until you are ready to make
connections.
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 system.
3 − Use silver alloy brazing rods (5 or 6 percent minimum
silver alloy for copper−to−copper brazing or 45 percent
silver alloy for copper−to−brass or copper−to−steel brazing) which are rated for use with R410A refrigerant.
Wrap a wet cloth around the valve body and the copper
tube stub. Remove light maroon washers from service
valves and shield light maroon stickers in order to protect them during brazing. 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 brazing. 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 field−provided thermal expansion valve (ap-
proved for use with R410A refrigerant) in the liquid line
at the indoor coil.
Flushing Existing Line Set & Indoor Coil
WARNING
Danger of fire. Bleeding the refrigerant
charge from only the high side may
result 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.
IMPORTANT
If this unit is being matched with an approved line
set or indoor coil which was previously charged
with R22 refrigerant, or if it is being matched with
a coil which was manufactured before January of
1999, the coil and line set must be flushed prior to
installation. Take care to empty all existing traps.
Polyol ester (POE) oils are used in Lennox units
charged with R410A refrigerant. Residual mineral
oil can act as an insulator, preventing proper heat
transfer. It can also clog the thermal expansion
valve, reducing system performance and capacity.
Failure to properly flush the system per the instructions below will void the warranty.
CAUTION
This procedure should not be performed on systems which contain contaminants (Example: compressor burn out).
Required Equipment
You will need the following equipment in order to flush the
existing line set and indoor coil: two clean R22 recovery
bottles, an oilless recovery machine with a pump down feature, and two sets of gauges (one for use with R22 and one
for use with the R410A).
Flushing Procedure
1 − Remove existing R22 refrigerant using the appropri-
ate procedure below.
If the existing outdoor unit is not equipped with
shut−off valves, or if the unit is not operational
AND you plan to use the existing R22 refrigerant to
flush the system −− Disconnect all power to the exist-
ing outdoor unit. Connect the existing unit, a clean recovery cylinder and the recovery machine according
to the instructions provided with the recovery machine. Remove all R22 refrigerant from the existing
system. Refer to gauges after shutdown to confirm
that the entire system is completely void of refrigerant.
Disconnect the liquid and vapor lines from the existing
outdoor unit.
If the existing outdoor unit is equipped with manual shut−off valves AND you plan to use NEW R22
refrigerant to flush the system −− Start the existing
R22 system in the cooling mode and close the liquid
line valve. Pump all of the existing R22 refrigerant
back into the outdoor unit. (It may be necessary to bypass the low pressure switches to ensure complete refrigerant evacuation.) When the low side system pressures reach 0 psig, close the vapor line valve. Disconnect all power to the existing outdoor unit. Refer to
Page 9
gauges after shutdown to confirm that the valves are
not allowing refrigerant to flow back into the low side of
the system. Disconnect the liquid and vapor lines from
the existing outdoor unit.
2 − Remove the existing outdoor unit. Set the new R410A
unit and follow the brazing connection procedure
which begins on the previous page to make line set
connections. DO NOT install provided R410A
check/expansion valve at this time.
Make low voltage and line voltage connections to the
new outdoor unit. DO NOT turn on power to the unit
or open the outdoor unit service valves at this
time.
Flushing Connections
INVERTED R22
CYLINDER
(Contains clean
R22 to be used for
flushing)
SERVICE VALVE
EXISTING
INDOOR COIL
EXISTING VAPOR LINE
EXISTING LIQUID LINE
3 − Remove the existing refrigerant flow control orifice or
The line set and indoor coil must be flushed with at
least the same amount of clean refrigerant that previously charged the system. Check the charge in
the flushing cylinder before proceeding.
VAPOR LINE
LIQUID LINE
SERVICE VALVE
thermal expansion/check valve before continuing with
flushing procedures. The existing devices are not approved for use with R410A refrigerant and may prevent proper flushing. Use a field−provided fitting to reconnect the lines.
IMPORTANT
HPXA12 UNIT
LOW
PRESSURE
GAUGE MANIFOLD
HIGH
PRESSURE
CLOSEDOPENED
RECOVERY
CYLINDER
TANK RETURN
INLET
DISCHARGE
RECOVERY MACHINE
Figure 11
NOTE − The inverted R22 cylinder must contain at least the
same amount of refrigerant as
was recovered from the existing
system.
Page 10
4 − Remove the pressure tap valve cores from the
HPXA12 unit’s service valves. Connect an R22 cylinder with clean refrigerant to the vapor service valve.
Connect the R22 gauge set to the liquid line valve and
connect a recovery machine with an empty recovery
tank to the gauge set.
5 − Set the recovery machine for liquid recovery and start
the recovery machine. Open the gauge set valves to
allow the recovery machine to pull a vacuum on the existing system line set and indoor coil.
6 − Invert the cylinder of clean R22 and open its valve to
allow liquid refrigerant to flow into the system through
the vapor line valve. Allow the refrigerant to pass from
the cylinder and through the line set and the indoor coil
before it enters the recovery machine.
7 − After all of the liquid refrigerant has been recovered,
switch the recovery machine to vapor recovery so that
all of the R22 vapor is recovered. All the recovery machine to pull a vacuum on the system.
NOTE − A single system flush should remove all of the
mineral oil from the existing refrigerant lines and indoor coil. A second flushing may be done (using clean
refrigerant) if insufficient amounts of mineral oil were
removed during the first flush. Each time the system
is flushed, you must allow the recovery machine
to pull a vacuum on the system at the end of the
procedure.
8 − Close the valve on the inverted R22 drum and the
gauge set valves. Pump the remaining refrigerant out
of the recovery machine and turn the machine off.
9 − Use nitrogen to break the vacuum on the refrigerant
lines and indoor coil before removing the recovery machine, gauges and R22 refrigerant drum. Reinstall
pressure tap valve cores into HPXA12 service valves.
10 −Install the provided check/expansion valve (approved
for use with R410A refrigerant) in the liquid line at the
indoor coil.
Refrigerant Metering Device
HPXA12 units are applicable to check expansion valve
systems only. See indoor coil installation instructions and
the Lennox engineering handbook for approved R410A
TXV match−ups and application information.
NOTE − R410A systems will not operate properly with an
R−22 valve.
Check Expansion Valve Systems
Check expansion valves equipped with either Chatleff or
flare−type fittings are available from Lennox. Refer to the
Engineering Handbook for applicable expansion valves
for use with specific match-ups. See table 2 for applicable
check and expansion valve kits.
If you install a check expansion valve with an indoor coil
that includes a fixed orifice, remove the orifice before
the check expansion valve is installed.
IMPORTANT
Failure to remove RFC when installing an expansion
valve to the indoor coil will result in improper operation and damage to the system.
Table 2
Indoor Check Expansion Valve Kits
Model Kit Catalog Number
HPXA12−018
HPXA12−024
HPXA12−030
HPXA12−036
HPXA12−042
HPXA12−048
HPXA12−060
See figure 12 for installation of the check expansion valve.
Metering Device Installation
distributor
expansion
o−ring
strainer
liquid line
Figure 12
Manifold Gauge Set
Manifold gauge sets used with systems charged with
R410A refrigerant must be capable of handling the higher
system operating pressures. The gauges should be rated
for use with pressures of 0 − 800 on the high side and a low
side of 30" vacuum to 250 psi with dampened speed to 500
psi. Gauge hoses must be rated for use at up to 800 psi of
pressure with a 4000 psi burst rating.
Service Valves
The liquid line and vapor line service valves (figures 13 and
14) and gauge ports are used for leak testing, evacuating,
charging and checking charge. See table 3 for torque requirements.
Each valve is equipped with a service port which has a factory−installed Schrader valve. A service port cap protects
the Schrader valve from contamination and serves as the
primary leak seal.
49L24
49L25
o−ring
valve
stub
Page 11
Table 3
Torque Requirements
Part Recommended Torque
Service valve cap 8 ft.− lb. 11 N M
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 N M
to outdoor coil
service
port cap
Service Valve
(Valve Closed)
stem cap
service
port
insert hex
wrench here
IMPORTANT
Service valves are closed to the outdoor unit and
open to line set connections. Do not open until refrigerant lines have been leak tested and evacuated. All
precautions should be exercised in keeping the system free from dirt, moisture and air.
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 using 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, and tighten it firmly. Tighten finger
tight, then tighten an additional 1/6 turn.
Schrader valve open
to line set when valve is
closed (front seated)
insert hex
wrench here
service
port
to outdoor coil
service port
cap
Schrader
valve
(valve front seated)
Service Valve
(Valve Open)
Figure 13
to indoor coil
stem cap
to indoor coil
Page 12
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 stem cap. Tighten finger tight, then tighten an
additional 1/6 turn.
Ball−Type Vapor Valve
Vapor line service valves function the same way as the other 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.
Vapor Line (Ball Type) Service Valve
(Valve Open)
To open: Rotate stem counter-clockwise 90.
to outdoor coil
service port
cap
Use adjustable wrench
To close: Rotate stem clockwise 90.
stem cap
stem
ball
(shown open)
to indoor coil
service port
Schrader valve
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 explosion: Can cause
equipment damage, injury or death.
Never use oxygen to pressurize a refrigeration 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
1 − Connect a cylinder of R410A to the center port of the
manifold gauge set.
2 − With both manifold valves closed, open the valve on
the R410A cylinder (vapor only).
3 − Open the high pressure side of the manifold to allow
the R410A into the line set and indoor unit. Weigh in a
trace amount of R410A . [A trace amount is a maximum
of 2 ounces (57 g) or 3 pounds (31 kPa) pressure.]
Close the valve on the R410A cylinder and the valve
on the high pressure side of the manifold gauge set.
Disconnect the R410A 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 manifold 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.
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 R410A
mixture. Correct any leaks and recheck.
WARNING
Refrigerant can be harmful if it is inhaled. Refrigerant must be used and recovered responsibly.
IMPORTANT
Leak detector must be capable of sensing HFC refrigerant.
Page 13
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 piping 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
as follows:
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 the vacuum
pump.
5 − Evacuate the line set and indoor unit to an absolute
pressure of 23,000 microns (29.01 inches of mercury). During the early stages of evacuation, it is desirable 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 pressure in a vacuum is equal to atmospheric pressure minus 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 cylinder 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.
WARNING
Danger of Equipment Damage.
Avoid deep vacuum operation. Do not use compressors 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 20−minute 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 vacuum pump and connect it to an upright cylinder of R410A
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 R410A cylinder and remove the manifold
gauge set.
Start−Up
IMPORTANT
Crankcase heater (if applicable) should be energized
24 hours before unit start−up to prevent compressor
damage as a result of slugging.
1 − Rotate 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 (counterclockwise) to release
refrigerant charge (contained in outdoor unit) into the
system.
4 − Replace stem caps and secure finger tight, then tight-
en an additional (1/6) one-sixth of a turn.
5 − Check voltage supply at the disconnect switch. The
voltage must be within the range listed on the unit
nameplate. If not, do not start the equipment until the
power company has been consulted and the voltage
condition has been corrected.
Page 14
6 − Set the thermostat for a cooling demand, turn on power
to indoor blower unit and close the outdoor unit disconnect to start the unit.
7 − Recheck voltage while the unit is running. Power must
be within range shown on the nameplate.
Charging
This system is charged with R410A refrigerant which operates at much higher pressures than R22. The recommended check expansion valve is approved for use with
R410A. Do not replace it with a valve that is designed to be
used with R22. This unit is NOT approved for use with coils
that include metering orifices or capillary tubes.
Processing Procedure
The unit is factory−charged with the amount of R410A refrigerant indicated on the unit rating plate. This charge is
HPXA12 COOLING CYCLE
(Showing Gauge Manifold Connections)
OUTDOOR UNIT
DISTRIBUTOR
EXPANSION/
CHECK VALVE
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 2 for refrigerant charge adjustment. A blank space is
provided on the unit rating plate to list the actual field
charge.
Table 4
Liquid Line Set
Diameter
3/8 in.
(10 mm)
*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.
Oz. per 5 ft. (grams per 1.5 m) adjust
from 15 ft. (4.6 m) line set*
3 ounces per 5 feet
(85 g per 1.5 m)
IMPORTANT
Mineral oils are not compatible with R410A. If oil
must be added, it must be a polyol ester oil.
NOTE − ARROWS INDICATE
REVERSING VALVE
DIRECTION OF REFRIGERANT FLOW
OUTDOOR
LOW
PRESSURE
GAUGE MANIFOLD
NOTE−Use gauge ports on vapor line valve and liquid valve for evacuating refrigerant lines
and indoor coil. Use vapor gauge port to measure vapor pressure during charging.
TO
R410A
DRUM
HIGH
PRESSURE
LIQUID
LINE
SERVICE
PORT
BIFLOW
FILTER / DRIER
MUFFLER
COIL
COMPRESSOR
VAPOR
SERVICE
PORT
Figure 15
VAPOR
LINE
VALV E
EXPANSION/CHECK
VALV E
INDOOR UNIT
INDOOR
COIL
Page 15
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 unit’s refrigerant metering device and the
outdoor ambient temperature.
Measure the liquid line temperature and the outdoor ambient temperature as outlined below:
1 − Connect the manifold gauge set to the service valves:
low pressure gauge to vapor valve service port
high pressure gauge to liquid valve service port
Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of R410A. See figure 15.
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 charging 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 repaired.
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 procedures outlined below.
Subcooling Method
Outdoor Temp. < 65°F (18°C)
When the outdoor ambient temperature is below 65°F
(18°C), use the subcooling method to charge the unit. It
may be necessary to restrict the air flow through the outdoor coil to achieve pressures in the 325−375 psig
(2240−2585 kPa) range. These higher pressures are necessary for checking the charge. Block equal sections of air
intake panels and move obstructions sideways until the liquid pressure is in the 325−375 psig (2240−2585 kPa) range.
See figure 16.
Blocking Outdoor Coil
*Outdoor coil should be
blocked one side
at a time with cardboard
or plastic sheet until proper
testing pressures
are reached.
cardboard or
plastic sheet
*four−sided
unit shown
Figure 16
1 − With the manifold gauge hose still on the liquid service
port and the unit operating stably, use a digital thermometer to record the liquid line temperature.
2 − At the same time, record the liquid line pressure reading.
3 − Read the liquid line pressure from the gauge and convert
it to heat pump temperature using the temperature/pressure chart for R410A refrigerant provided in table 8.
4 − Subtract the liquid line temperature from the saturation
temperature (according to the chart) to determine subcooling. (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 refrigerant. If subcooling is less than shown, add some refrigerant. Some R410A cylinders are equipped with
a dip tube which allows you to draw liquid refrigerant from the bottom of the cylinder without turning
the cylinder upside−down. The cylinder will be
marked if it is equipped with a dip tube.
Table 5
Subcooling Values for Charging
Model Number
HPXA12−18 8.5 (4.7)
HPXA12−24 12.5 (6.9)
HPXA12−30 5.5 (3.1)
HPXA12−36 8.5 (4.7)
HPXA12−42 8.5 (4.7)
HPXA12−48 7 (3.9)
HPXA12−60 7 (3.9)
Conversion Temp. − Liquid Line Temp. °F (°C)
Subcooling Values
Charging Using Normal Operating Pressures
and the Approach Method
Outdoor Temp. >
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 70°F (21°C) to 80°F (26°C).
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.
65F (18C)
Page 16
3 − Compare stabilized pressures with those provided in
)
)
table 7, Normal Operating Pressures." 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.
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 temperature. Verify the unit charge using the approach method.
The difference between the ambient and liquid temperatures should match values given in table 6. Add refrigerant to lower the approach temperature and remove it
to increase the approach temperature. Loss of charge
results in low capacity and efficiency.
5 − If the values do not agree with the those in table 6, add
refrigerant to lower the approach temperature or recover refrigerant from the system to increase the approach temperature.
Table 6
Approach Values for Charging
Model Number Approach Temperature
Liquid Line Temp. − Outdoor Ambient °F (°C)
HPXA12−18 5 (2.8)
HPXA12−24 8.0 (4.4)
HPXA12−30 12.5 (6.9)
HPXA12−36 13 (7.2)
HPXA12−42 13 (7.2)
HPXA12−48 8.5 (4.7)
HPXA12−60 12 (6.7)
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.
Outdoor Coil
Entering Air
Temp. °F (°C
65 (18.3)
75 (23.9)
85 (29.4)
95 (35.0)
105 (40.6)
115 (46.1)
Outdoor Coil
Entering Air
Temp. °F (°C
20 (−6.6)
30 (−1.1)
40 (4.4)
50 (10.0)
60 (15.5)
HPXA12−18
Liquid Vapor
223 147
270 149
312 150
360 152
406 154
463 155
HPXA12−18
Liquid Vapor
265 63
280 78
294 96
310 112
320 133
Table 7
Normal Operating Pressures
(Liquid ±10 and Vapor ±5 psig)
Cooling Operation
HPXA12−24 HPXA12−30 HPXA12−36 HPXA12−42 HPXA12−48 HPXA12−60
Liquid vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor
254 130 244 136 262 135 260 133 240 126 250 123
290 134 282 139 304 138 300 135 280 130 300 132
335 137 325 141 349 141 345 137 320 134 345 137
382 140 375 143 399 143 397 139 360 136 378 140
433 143 426 145 454 146 452 142 415 137 430 142
490 146 485 147 514 149 510 145 470 139 497 145
Heating Operation
HPXA12−24 HPXA12−30 HPXA12−36 HPXA12−42 HPXA12−48 HPXA12−60
Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor
295 59 340 60 278 59 288 60 315 60 282 57
315 72 350 75 290 72 297 70 325 74 300 70
335 87 362 90 305 89 310 85 340 90 310 82
350 103 374 110 317 105 325 105 360 106 325 92
375 120 390 132 333 128 344 127 380 128 335 100
Page 17
Table 8
R410A Temperature/Pressure Chart
Temp.°F Pressure Psig Temp.°F Pressure Psig Temp. °F Pressure Psig Temp. °F Pressure Psig
32 100.8 63 178.5 94 290.8 125 445.9
33 102.9 64 181.6 95 295.1 126 451.8
34 105.0 65 184.3 96 299.4 127 457.6
35 107.1 66 187.7 97 303.8 128 463.5
36 109.2 67 190.9 98 308.2 129 469.5
37 111.4 68 194.1 99 312.7 130 475.6
38 113.6 69 197.3 100 317.2 131 481.6
39 115.8 70 200.6 101 321.8 132 487.8
40 118.0 71 203.9 102 326.4 133 494.0
41 120.3 72 207.2 103 331.0 134 500.2
42 122.6 73 210.6 104 335.7 135 506.5
43 125.0 74 214.0 105 340.5 136 512.9
44 127.3 75 217.4 106 345.3 137 519.3
45 129.7 76 220.9 107 350.1 138 525.8
46 132.2 77 224.4 108 355.0 139 532.4
47 134.6 78 228.0 109 360.0 140 539.0
48 137.1 79 231.6 110 365.0 141 545.6
49 139.6 80 235.3 111 370.0 142 552.3
50 142.2 81 239.0 112 375.1 143 559.1
51 144.8 82 242.7 113 380.2 144 565.9
52 147.4 83 246.5 114 385.4 145 572.8
53 150.1 84 250.3 115 390.7 146 579.8
54 152.8 85 254.1 116 396.0 147 586.8
55 155.5 86 258.0 117 401.3 148 593.8
56 158.2 87 262.0 118 406.7 149 601.0
57 161.0 88 266.0 119 412.2 150 608.1
58 163.9 89 270.0 120 417.7 151 615.4
59 166.7 90 274.1 121 423.2 152 622.7
60 169.6 91 278.2 122 428.8 153 630.1
61 172.6 92 282.3 123 434.5 154 637.5
62 195.5 93 286.5 124 440.2 155 645.0
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.
Service Light Operation
The thermostat is not included with the unit and must be
purchased separately. Some outdoor thermostats incorporate isolating contacts and an emergency heat function
(which includes an amber indicating light). The service light
thermostat will enable the emergency heat light function on
the room thermostat.
Emergency Heat (Amber Light)
An emergency heat function is designed into some room thermostats. This feature is applicable when isolation of the 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 relays 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 unit
shutdown, but it should also be used following a power outage if power has been off for over an hour and the outdoor
temperature is below 50°F (10°C). System should be left in
the emergency heat mode at least six hours to allow the
crankcase heater sufficient time to prevent compressor
slugging.
Filter Drier
The unit is equipped with a large−capacity biflow filter drier
which keeps the system clean and dry. If replacement is
necessary, order another of the same design and capacity.
The replacement filter drier must be suitable for use with
R410A refrigerant.
Page 18
Defrost System
Low Pressure Switch
The HPXA12 is equipped with an auto−reset low pressure
switch which is located on the vapor line. The switch shuts
off the compressor when the vapor pressure falls below the
factory setting. This switch is ignored during defrost operation and when the outdoor temperature goes below 15°F.
The switch closes when it is exposed to 60 psig and opens
at 25 psig. It is not adjustable.
HPXA12 Defrost Control Board
Note − Component Locations Will Vary With Board Manufacturer
pressure switch
circuit connections
High Pressure Switch
The HPXA12 is equipped with an auto−reset high pressure
switch (single−pole, single−throw) which is located on the
liquid line. The switch shuts off the compressor when discharge pressure rises above the factory setting. The switch
is normally closed and is permanently adjusted to trip
(open) at 640 + 10 psig (4412 + 69 kPa).
NOTE − A Schrader core is under the pressure switches.
diagnostic LEDs
defrost interval
timing pins
reversing valve
coil
sensor
Y2
Figure 17
DELAY
Y2
24V terminal strip
connections
field select
temperature pins
ambient
sensor
Page 19
Demand Defrost System
The demand defrost controller uses basic differential temperature means to detect when the system performs poorly because of ice build−up on the outdoor coil. The controller also uses self−calibrating" principles to calibrate itself
when the system starts and after every time the system
defrosts. The control board has the following components: defrost relays, anti−short cycle timed−off control,
pressure switch/safety control, 5−trip lockout circuit,
manufacturing test mode, ambient and coil temperature
sensors, field selectable termination temperature pins, and
a field low voltage connection terminal strip. See figure 17.
The control monitors ambient temperature, outdoor coil
temperature and total run time to determine when a defrost cycle is required. Two temperature probes are permanently attached to the control. The coil temperature
probe is designed with a spring clip to allow mounting to
the outside coil tubing. The location of the coil sensor is
important for proper defrost operation.
NOTE − The logic of the demand defrost board accurately
measures the performance of the system as frost accumulates on the outdoor coil. This typically will translate into
longer running time between defrost cycles as more frost
accumulates on the outdoor coil before the board initiates
defrost cycles.
The temperature probes cannot be removed from the control. The control and the attached probes MUST be replaced as a unit. Do not attempt to cut or splice probe wires.
Diagnostic LEDs
The defrost board uses two LEDs for diagnostics. The
LEDs flash a specific sequence according to the diagnostic condition. See table 9.
HI−PS/LO−PS Terminals
The unit’s automatic reset pressure switches are wired to
the PS terminals. The high−pressure switch is factory
wired to the HI−PS terminal, and the low−pressure switch
is factory−wired to LO−PS terminal.
The path between Y1 (input) and Y1 Out is interlocked
through the pressure switches. When one of the pressure
switches trip, the board will cycle off the compressor and
the 5−strike counter in the board will count one strike.
5−Strike Lockout Feature
The internal control logic of the board counts the pres-
sure switch trips only while the Y1 (Input) line is active. If
a pressure switch opens and closes twice during a Y1
(Input), the control logic will reset the pressure switch
trip counter to zero at the end of the Y1 (Input). If the
pressure switch opens for a fifth time during the current
Y1 (Input), the control will enter a lockout condition.
The 5−strike pressure switch lockout condition can be
reset by cycling OFF the 24−volt power to the control
board or by shorting the TEST pins. All timer functions
(run times) will also be reset.
If a pressure switch opens while the Y1 Out line is en-
gaged, a 5−minute short cycle will occur after the switch
closes.
Delay Mode
The defrost board has a field−selectable function to reduce
occasional sounds that may occur while the unit is cycling
in and out of the defrost mode. When a jumper is installed
on the DELAY pins, the compressor will be cycled off for 30
seconds going in and out of the defrost mode. Units are
shipped with jumper installed on DELAY pins.
NOTE − The 30 second off cycle is not functional when jumpering the TEST pins.
Operational Description
The defrost control board has three basic operational
modes: normal, defrost, and calibration.
Normal Mode
The demand defrost board monitors the O line, to determine the system operating mode (heat/cool), outdoor ambient temperature, coil temperature (outdoor coil) and
compressor run time to determine when a defrost cycle is
required.
Defrost Mode
Refer to table 9 for demand defrost operation.
Calibration Mode
The board is considered uncalibrated when power is applied to the board, after cool mode operation, or if the coil
temperature exceeds the termination temperature when it
is in heat mode. Calibration of the board occurs after a defrost cycle to ensure that there is no ice on the coil. During
calibration, the temperature of both the coil and the ambient sensor are measured to establish the temperature differential which is required to allow a defrost cycle.
Page 20
Table 9
Improper refrigerant charge
tion
Defrost Control Board Diagnostic Led
LED 1 LED 2 Condition Possible Cause(s) Solution
1
No power (24V) to board terminals
OFF OFF Power problem
ON ON Coil sensor problem
OFF ON Ambient sensor problem
FLASH FLASH Normal operation
5−Strike pressure lockout
ON OFF
(Short test pins or reset
24V power to board to
override lockout)
ON FLASH
Low pressure switch circuit
open during Y1 demand
High pressure switch cir-
FLASH ON
cuit open during Y1 demand
ALTERNATING
FLASH
ALTERNATING
FLASH
5−minute delay
(Jumper test pins to override delay)
R & C.
2
Board failure.
1
Coil temperature outside of sensor
range.
2
Faulty sensor wiring connections at
board or poor sensor contact on coil.
3
Sensor failure.
1
Ambient temperature outside of
sensor range.
2
Faulty sensor wiring connections at
board or sensor.
3
Sensor failure.
Unit operating normally or in standby
mode.
1
Restricted air flow over indoor or
outdoor coil.
2
Improper refrigerant charge.
3
Improper metering device opera-
tion.
.
4
Poor contact between coil sensor
.
and coil.
Thermostat demand for cooling or
outdoor operation. Unit operating in
5−minute anti−short−cycle mode.
Demand Defrost Operation
The demand defrost control board initiates a defrost cycle based on either frost detection or time.
Frost Detection − If the compressor runs longer than 34 minutes and the actual difference between the clear coil and frosted coil temperatures exceeds
the maximum difference allowed by the control, a defrost cycle will be initiated.
IMPORTANT − The demand defrost control board will allow a greater accumulation of frost and will initiate fewer defrost cycles than a time/temperature
defrost system.
Time − If 6 hours of heating mode compressor run time has elapsed since the last defrost cycle while the coil temperature remains below 35°F (2°C),
the demand defrost control will initiate a defrost cycle.
Actuation − When the reversing valve is de−energized, the Y1 circuit is energized, and the coil temperature is below 35°F (2°C), the board logs the
compressor run time. If the board is not calibrated, a defrost cycle will be initiated after 34 minutes of heating mode compressor run time. The control
will attempt to self−calibrate after this (and all other) defrost cycle(s). Calibration success depends on stable system temperatures during the 20−minute
calibration period. If the board fails to calibrate, another defrost cycle will be initiated after 90 minutes of heating mode compressor run time. Once the
defrost board is calibrated, it will use demand defrost logic to initiate a defrost cycle. A demand defrost system initiates defrost when the difference between the clear coil and frosted coil temperatures exceeds the maximum difference allowed by the control OR after 6 hours of heating mode compressor
run time has been logged since the last defrost cycle.
Termination − The defrost cycle ends when the coil temperature exceeds the termination temperature or after 14 minutes of defrost operation. If the
defrost is terminated by the 14−minute timer, another defrost cycle will be initiated after 34 minutes of run time.
Test Mode − When Y1 is energized and 24V power is being applied to the board, a test cycle can be initiated by placing the termination temperature
jumper across the Test" pins for 2 to 5 seconds. If the jumper remains across the Test" pins longer than 5 seconds, the control will ignore the test pins
and revert to normal operation. The jumper will initiate one cycle per test.
1
Check control transformer power
(24V).
2
If power is available and LED(s) are
unlit, replace board and all sensors.
1
Sensor function will resume when
coil temperature is between −20°F
and 110°F.
2
Check sensor wiring connections at
board and sensor contact on coil.
3
Replace board and all sensors.
1
Sensor function will resume when
coil temperature is between −20°F
and 110°F.
2
Check sensor wiring connections at
board and sensor.
3
Replace board and all sensors.
None required.
1
Remove any blockages or restric-
tions. Check outdoor fan motor for
proper operation.
2
Check approach, superheat & sub-
cooling temperatures.
3
Check system pressures. Repair
leaks. Replace metering device.
4
Make sure that sensor is properly
positioned on coil and that firm contact is established. Refer to service
manual for proper placement.
None required.
Page 21
Maintenance
Optional Accessories
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 disconnect 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
season, the system should be checked as follows:
Outdoor Unit
1 - Clean and inspect outdoor coil (may be flushed with a
water hose). Ensure power is off before cleaning.
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 all 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 insufficient heating or cooling occurs, the unit
should be gauged and refrigerant charge should be
checked.
Refer to the Engineering Handbook for optional accessories 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
Stand−off Kit
Sound Cover
Low Ambient Kit
Monitor Kit
Mild Weather Kit
Homeowner Information
In order to ensure peak performance, your system must be
properly maintained. Clogged filters and blocked airflow
prevent your unit from operating at its most efficient level.
Ask your Lennox dealer to show you where your indoor
unit’s filter is located. It will be either at the indoor unit
(installed internal or external to the cabinet) or behind a return air grille in the wall or ceiling. Check the filter monthly
and clean or replace it as needed.
Disposable filters should be replaced with a filter of the
same type and size. If you are unsure about the filter you
need for your system, call your Lennox dealer for assistance.
IMPORTANT
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__________.
Turn off electrical power to the unit at the disconnect
switch before performing any maintenance. The unit
may have multiple power supplies.
Many indoor units are equipped with reusable foam filters. These filters can be cleaned with a mild soap and
water solution. Rinse the filter thoroughly and let it dry
completely before it is returned to the unit or grille.
The filter and all access panels must be in place any
time the unit is in operation.
Your system may be equipped with an electronic air cleaner which will provide respiratory relief by removing up to 90
percent of all airborne particles which pass through it. If it
is, ask your dealer to instruct you on its maintenance.
Your indoor coil is equipped with a drain pan to collect condensate formed as your system removes humidity from the
inside air. Have your dealer show you where the main condensate drain (and auxiliary drain, if applicable) runs and
how to check the drain for any obstruction.
It is also very important to provide unrestricted airflow to the
outdoor unit. Leaves, trash or shrubs crowding the unit
cause the outdoor unit to work harder and use more energy. Keep shrubbery trimmed away from the unit and period-
Page 22
ically check for debris which may have collected around the
unit.
Heat Pump Operation
Your new Lennox heat pump has several characteristics
that you should be aware of:
Your heat pump satisfies heating demand by delivering
large amounts of warm air into the living space. This is quite
different from gas- or oil-fired furnaces or an electric furnace which deliver lower volumes of considerably hotter air
to heat the space.
Do not be alarmed if you notice frost on the outdoor coil in
the winter months. Frost develops on the outdoor coil during the heating cycle when temperatures are below 45°F
(7°C). An electronic control activates a defrost cycle lasting
5 to 15 minutes at preset intervals to clear the outdoor coil
of the frost. During the defrost cycle, you may notice steam
rising from the outdoor unit. This is a normal occurrence.
The thermostat may engage auxiliary heat during the defrost cycle to satisfy a heating demand; however, the unit
will return to normal operation at the conclusion of the defrost cycle.
Your Lennox HPXA12 heat pump is equipped with a compressor crankcase heater which protects the compressor
from refrigerant slugging during cold weather operation. If
power to your unit has been interrupted for several hours
or more, set the room thermostat selector to the Emergency Heat" setting to obtain temporary heat without the risk
of serious equipment damage. In this operating mode, all
heating demand will be satisfied by auxiliary heat. Compressor operation is locked out during Emergency Heat operation. After a six-hour compressor crankcase heater
warm-up period, the thermostat can be switched to the
Heat" setting and normal operation will resume.
Thermostat Operation
Though your thermostat may vary somewhat from the description below, its operation will be similar.
Temperature Setting Levers
Most heat pump thermostats have two temperature selector levers: one for heating and one for cooling. Set the levers or dials to the desired temperature setpoints for both
heating and cooling. Avoid frequent temperature adjustment; turning the unit off and back on before pressures
equalize puts stress on the unit compressor.
Fan Switch
In AUTO or INT (intermittent) mode, the blower operates
only when the thermostat calls for heating or cooling. This
mode is generally preferred when humidity control is a
priority. The ON or CONT mode provides continuous indoor blower operation, regardless of whether the compressor or auxiliary heat are operating. This mode is required
when constant air circulation or filtering is desired.
System Switch
Set the system switch for heating, cooling or auto operation. The auto mode allows the heat pump to automatically
switch from heating mode to cooling mode to maintain predetermined comfort settings. Many heat pump thermostats
are also equipped with an emergency heat mode which
locks out heat pump operation and provides temporary
heat supplied by the auxiliary heat.
Indicating Light
Most heat pump thermostats have an amber light which indicates when the heat pump is operating in the emergency
heat mode.
Temperature Indicator
The temperature indicator displays the actual room temperature.
Programmable Thermostats
Your Lennox system may be controlled by a programmable
thermostat. These thermostats provide the added feature
of programmable time-of-day setpoints for both heating
and cooling. Refer to the user’s information manual provided with your particular thermostat for operation details.
Preservice Check
If your system fails to operate, check the following before
calling for service:
Check to see that all electrical disconnect switches are
ON.
Make sure the room thermostat temperature selector is
properly set.
Make sure the room thermostat system switch is proper-
ly set.
Replace any blown fuses, or reset circuit breakers.
Make sure unit access panels are in place.
Make sure air filter is clean.
Locate and record unit model number before calling.
Page 23
HPXA12 Check List
Job Name
Job Location
Installer
Unit Model No.
Nameplate Voltage
Rated Load Ampacity
Maximum Fuse or Circuit Breaker
Electrical Connections Tight?
Indoor Blower RPM
Cooling (2nd stage)
Liquid Line Pressure
Heating (2nd stage)
Liquid Line Pressure
Refrigerant Lines:
Service Valves Fully Opened?
Sequence of Operation
Heating Correct Cooling Correct
Leak Checked?
Start−Up and Performance Check List
S.P. Drop Over Indoor (Dry)
Service Valve Caps Tight?
Job No.
City
City
Serial No.
Amps: 1st stage
Indoor Filter Clean?
Vapor Pressure
Vapor Pressure
Properly Insulated?
Date
State
State
Service Technician
2nd Stage
Supply Voltage (Unit Off)
Outdoor Coil Entering Air Temp.
Refrigerant Charge Checked?
Refrigerant Charge Checked?
Outdoor Fan Checked?
Voltage With Compressor Operating
Thermostat
Calibrated? Properly Set? Level?
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