Lennox 4HP18LT User Manual

INSTALLATION AND MAINTENANCE INSTRUCTIONS

4HP18LT Series

Split System Heat Pump

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WARNING

The equipment covered in this manual is to be installed by trained and experienced service
and installation technicians. Improper installation, modification, service, or use can cause
electrical shock, fire, explosion, or other conditions which may cause personal injury , death,
or property damage. Use appropriate safety gear including safety glasses and gloves
when installing this equipment.

W ARNING

Risk of electrical shock. Disconnect all remote power
supplies before installing or servicing any portion of the
system. Failure to disconnect power supplies can result
in property damage, personal injury , or death.

INSTALLATION ....................................................2

CONNECTION DIAGRAM....................................4

TABLE OF CONTENTS

W ARNING

Installation and servicing of air conditioning equipment
can be hazardous due to internal refrigerant pressure
and live electrical components. Only trained and qualified
service personnel should install or service this equipment.
Installation and service performed by unqualified persons
can result in property damage, personal injury , or death.

WARNING

Sharp metal edges can cause injury. When installing
the unit, use care to avoid sharp edges.

START-UP..........................................................13

OPERATION ......................................................18

MAINTENANCE .................................................23

Manufactured By

Allied Air Enterprises, Inc.

A Lennox International Inc. Company

215 Metropolitan Drive

West Columbia, SC 29170

*506470-01*

506470-01 Issue 1007

Page 1

INSTALLATION

General

Read this entire instruction manual, as well as the
instructions supplied in separate equipment, before
starting the installation. Observe and follow all
warnings, cautions, instructional labels, and tags.
Failure to comply with these instructions could result
in an unsafe condition and/or premature component
failure.

These instructions are intended as a general guide only for
use by qualified personnel and do not supersede any national
or local codes in any way . The installation must comply with
all provincial, state, and local codes as well as the National
Electrical Code (U.S.) or Canadian Electrical Code (Canada).
Compliance should be determined prior to installation.

4HP18LT condensing units use R410A which is an ozone­friendly HFC refrigerant. The unit must be installed with a
matching indoor coil and line set. A filter drier approved for
use with R410A is inst alled in the unit.

IMPORTANT: This product has been designed and
manufactured to meet ENERGY STAR criteria for energy
efficiency when matched with appropriate coil components.
However, proper refrigerant charge and proper air flow are
critical to achieve rated capacity and efficiency . Inst allation
of this product should follow the manufacturer’s refrigerant
charging and air flow instructions. Failure to confirm proper

charge and airflow may reduce energy efficiency and
shorten equipment life.

Inspection of Shipment

Upon receipt of equipment, carefully inspect it for possible
shipping damage. If damage is found, it should be noted on
the carrier’s freight bill. Take special care to examine the
unit inside the carton if the carton is damaged. Any concealed
damage discovered should be reported to the last carrier
immediately, preferably in writing, and should include a
request for inspection by the carrier’s agent.

If any damages are discovered and reported to the carrier
DO NOT INST ALL THE UNIT, as claim may be denied.

Check the unit rating plate to confirm specifications are
as ordered.

Location of Unit

Outdoor units operate under a wide range of weather
conditions; therefore, multiple factors must be considered
when positioning the unit. The unit must be positioned to
give adequate clearances for sufficient airflow and servicing.
Refer to Figure 1 for installation clearances.

Installation Clearances

36”

36” *

36”

When servicing or repairing HV AC components, ensure the
fasteners are appropriately tightened. T able 1 shows torque
values for fasteners.

Torque Table

Fastener Torque

Stem Caps 8 ft. lbs.

Service Port Caps 8 ft. lbs.

Sheet Metal Screws

#8 Machine Screws

#10 Machine Screws

Compressor Bolts

Table 1

16 in. lbs.

16 in. lbs.

28 in. lbs.

90 in. lbs.

36” *

* A service clearance of 30" must be maintained on

one of the sides adjacent to the control box.
Clearance to one of the other three sides must be
36". Clearance to one of the remaining two sides may

be 12" and the final side may be 6".
A clearance of 24" must be maint ained between units.
48" clearance required on top of unit. Maximum soffit

overhang is 36".

Figure 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..

506470-01 Issue 1007

Page 2

• Install the unit high enough above the ground or roof to
allow adequate drainage of defrost water and prevent
ice buildup.

• In heavy snow areas, do not locate the unit where drifting
snow will occur. The unit base should be elevated above
the depth of average snows.

NOTE: Elevation of the unit may be accomplished by
construction a frame using suitable materials. If a
support frame is constructed, it must not block drain
holes in unit base.

• When installed in areas where low ambient temperatures
exist, locate unit so winter prevailing winds do not blow
directly into outdoor coil.

• Locate unit away from overhanging roof lines which
would allow water or ice to drop on, or in front of, coil or
into unit.

If unit coil cannot be mounted away from prevailing winter
winds, a wind barrier should be constructed (See Figure 3).
Size the barrier at least the same height and width as the
outdoor unit. Mount barrier 24” from the sides of the unit in
the direction of the prevailing winds.

Slab Mounting

When installing a unit at grade level, install on slab high
enough above 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° or 2” per 5’.
This will prevent ice from building up under the unit during a
defrost cycle. Refer to following roof mounting section for
barrier construction if unit must face prevailing winter winds.

Slab Mounting

Discharge Air

Building

Structure

Mounting Slab

Ground Level

Figure 3

Electrical Wiring

All field wiring must be done in accordance with the National
Electrical Code (NEC) recommendations, Canadian
Electrical Code (CEC) and CSA Standards, or local codes,
where applicable.

Refer to the furnace or blower coil installation instructions
for additional wiring application diagrams and refer to unit
rating plate for minimum circuit ampacity and maximum
overcurrent protection size.

W ARNING

Unit must be grounded in accordance with national and
local codes. Failure to ground unit properly can result in
personal injury or death.

Figure 2

Roof Mounting

Install unit at a minimum of 6” above surface of the roof 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.

506470-01 Issue 1007

WARNING

Line voltage is present at all components when unit is
not in operation on units with single pole contactors.
Disconnect all remote electric power supplies before
opening access panel. Unit may have multiple power
supplies. Failure to disconnect all power supplies could
result in personal injury or death.

Page 3

Figure 4

1. Install line voltage power supply to unit from a properly
sized disconnect switch. Any excess high volt age field
wiring should be trimmed or secured away from the low
voltage field wiring.

Refrigerant Piping

If the 4HP18L T unit is being inst alled with a new indoor coil
and line set, the refrigerant connections should be made as
outlined in this section. If an existing line set and/or indoor
coil will be used to complete the system, refer to this section
as well as the section that follows entitled - Flushing
Existing Line Set and Indoor Coil.

If this unit is being matched with an approved line set or
indoor coil which was previously charged with R-22
refrigerant, the line set and coil must be flushed prior to
installation. If the unit is being used with and existing indoor
coil which was equipped with a liquid line which served as a
metering device (RFCI), the liquid line must be replaced prior
to the installation of the 4HP18L T unit.

Field refrigerant piping consists of liquid and suction lines
from the outdoor unit (sweat connections) to the indoor coil
(flare or sweat connections).

Select line set diameters from Table 2 to ensure that oil
returns to the compressor. Size vertical suction riser to
maintain minimum velocity at minimum capacity.
Recommended line length is 50’ or less. If more than 50’
line set is required, contact Technical Services. Table 2
shows the diameters for line sets up to 100’ although vertical
lift applications and trapping requirements need to be
reviewed with Technical Services for line sets over 50’.

2. Ground unit at unit disconnect switch or to an earth
ground. To facilitate conduit, a hole is in the bottom of
the control box. Connect conduit to the control box
using a proper conduit fitting. 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 high voltage field wiring diagram.
A complete unit wiring diagram is located inside the unit
control box cover.

3. Install room thermostat on an inside wall that is not
subject to drafts, direct sunshine, or other heat sources.

4. Install low voltage wiring from outdoor to indoor unit
and from thermostat to indoor unit. (See Wire Diagram
on page 27.)

5. Do not bundle any excess 24V control wire inside
control box. Run control wire through installed wire tie
and tighten wire tie to provide low voltage strain relief
and to maintain seperation of field-installed low and high
voltage circuits.

Installing Refrigerant Line

During the installation of an air conditioning system, it is
important to properly isolate the refrigerant line to prevent
unnecessary vibration. Line set contact with the structure
(wall, ceiling, or floor) may cause objectionable noise when
vibration is translated into sound. As a result, more energy
or vibration can be expected. Close attention to line set
isolation must be observed.

Following are some points to consider when placing and
installing a high-efficiency outdoor unit:

506470-01 Issue 1007

Page 4

Placement

Install unit away

from windows

Two 90° elbows installed in lineset
will reduce lineset vibration

Be aware that some localities are adopting sound ordinances
based on how noisy the unit is at the neighbor’s home, 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 bedroom window . Glass has a verry high
level of sound transmission. Figure 5 shows how to place
the outdoor unit and line set to reduce line set vibration.

Brazing Connection Procedure

1. Cut ends of refrigerant lines square (free from nicks or
dents). Debur the ends. The pipe must remain round; do
not pinch end of 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.

Line Set Isolation

Illustrations on pages 6 and 7 demonstrate procedures which
ensure proper refrigerant line set isolation. Figure 6 shows
how to install line sets on horizontal runs. Figure 7 shows
how to make a transition from horizontal to vertical. Figure
8 shows how to install line sets on vertical runs.

Refrigerant Line Set Diameters (in.)

Liquid Line

Line Set Length and Size

BTUH

12 f t . 25 ft. 50 ft. 75 ft. 100 ft.

24,000

36,000

48,000

60,000

3/8 3/8 3/8 3/8 3/8

3/8 3/8 3/8 3/8

3/8 3/8 3/8 1/2

3/8 3/8 3/8 1/2

1/2

1/2

1/2

3. Use silver alloy brazing rods (5% or 6% silver alloy for
copper-to-copper brazing or 45% silver alloy for copper-to­brass or copper-to-steel brazing) which are rated for use
with R410A refrigerant.

4. Remove the Schrader core assemblies before brazing to
protect them from damage due to extreme heat. Replace
the cores when brazing is complete.

5. Remove light maroon washers from service valves and
shield light maroon stickers to protect them during brazing.
Wrap a wet cloth around the valve body and copper tube
stub to protect it from heat damage.

Outside Unit Placement & Installation

S uction Line

Line Set Length and Size

BTUH

12 f t . 25 ft. 50 ft. 75 ft. 100 ft.

24,000

36,000

48,000

60,000 1/8 1/8 1-1/8

3/4 3/4

7/8

7/8

3/4 3/4

7/8

7/8

For installations exceeding 50’, contact

T echnical Services.

Table 2

7/8

7/87/8

1-1/8

1-1/8

7/8

1-1/8

1-1/8

1-1/8

Figure 5

506470-01 Issue 1007

Page 5

6. Braze the line set to the service valve. Quench the joints

with water or a wet cloth to prevent heat damage to the
valve core and opening port. The tube end must stay

bottomed in the fitting during final assembly to ensure
proper seating, sealing, and rigidity .

7. Install the thermal expansion valve which is sold

separately and which is approved for use with R410A
refrigerant in the liquid line at the indoor coil (see Refrigerant

Metering Device on page 9).

Refrigerant Line Sets: Installing Horizont al Runs

CAUTION

When flushing existing line set and/or indoor coil, be sure to
empty all existing traps. 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 system as explained
in these instructions will void warranty .

To hang line set from joist or rafter,
use either metal strapping material
or anchored heavy nylon wire ties.

Strapping Material

(around vapor line only)

8’

Floor Joist or

Roof Rafter

Metal Sleeve

Floor Joist or Roof Rafter

Wire Tie

(around vapor line only)

Tape or Wire Tie

8’

Strap the vapor line to the joist or rafter
at 8 intervals then strap the liquid line

’

to the vapor line.

Tape or Wire Tie

Figure 6

506470-01 Issue 1007

Page 6

Refrigerant Line Sets: Transition from Vertical to Horizontal

Heavy Nylon

Wall

Stud

Metal Sleeve

Anchored

Wire Tie

Strap Liquid
Line to Vapor
Line

Liquid Line

Vapor Line Wrapped

–

in Armaflex

Figure 7

Muffler-Type

Wall

Stud

Metal Sleeve

Automotive

Hanger

Strap Liquid
Line to Vapor
Line

Liquid Line

Vapor Line Wrapped

–

in Armaflex

Refrigeraant Line Sets: Installing Vertical Runs (new construction shown)

NOTE: Similar installation practices

should be used if line set is to be
installed on exterior of outside wall.

Vapor Line Wrapped

IMPORTANT:

Refrigerant

lines must not

contact structure.

Outside Wall

Wood Block

Between Studs

with Armaflex

Outside Wall

Liquid Line

Caulk

IMPORTANT: Refrigerant
lines must not contact wall.

Vapor Line

Liquid Line

Wire Tie

Inside Wall

Strap

Sleeve

Wire Tie

Wood Block

Wire Tie

Strap

PVC Pipe

506470-01 Issue 1007

Fiberglass
Insulation

Figure 8

Sleeve

Page 7

Flushing Existing Line Set and Indoor Coil

This procedure should not be performed on systems
which contain contaminant s, such as compressor burn
out.

Required Euipment

The following equipment is needed to flush the existing line
set and indoor coil (See Figure 9). T wo clean R-22 recovery
bottles, an oil-less recovery machine with a “pump down”
feature, and two sets of gauges (one for use with R-22 and
one for use with R410A).

from the existing system. Refer to the gauges after shutdown
to confirm that the entire system is completely void of
refrigerant. Disconnect the liquid and suction lines from the
existing outdoor unit.

If the existing outdoor unit is equipped with manual shutoff
valves AND new R-22 refrigerant will be used to flush the
system:

Start the existing R-22 refrigerant system in cooling mode
and close the liquid line valve. Pump all the existing R-22
refrigerant back into the outdoor unit.

Flushing Procedure

IMPORTANT: The line set and/or indoor coil must be
flushed with at least the same amount of refrigerant that
previously charged the system. Check the charge in the
flushing cylinder before flushing the unit.

1. Remove existing R-22 refrigerant using the appropriate

procedure.

If the existing outdoor unit is not equipped with shutoff valves,
or if the unit is not operational AND the existing R-22
refrigerant will be used to flush the system:

Disconnect all power to the existing 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 R-22 refrigerant

Flushing Connections

(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 suction line valve. Disconnect all power to the existing
outdoor unit. Refer to the 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 suction
lines from the existing outdoor unit.

2. Remove the existing outdoor unit. Set the new R410A
unit and follow the brazing connection procedure outlined
previously on this page to make line set connections. Do

not install the R410A thermal expansion valve at this
time.

3. 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.

Figure 9

506470-01 Issue 1007

Page 8

4. Remover the existing R-22 refrigerant flow control orifice

or thermal expansion valve before continuing with flushing
procedures. R-22 flow control devices are not approved for
use with R410A refrigerant and may prevent proper flushing.
Use a field-provided fitting to reconnect the lines.

5. Remove the pressure tap valve cores from the 4HP18L T

units service valves. Connect an R-22 cylinder with clean
refrigerant to the suction service valve. Connect the R-22
gauge set to the liquid line valve and connect a recovery
maching with an empty recovery tank to the gauge set.

6. 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.

7. Invert the cylinder of clean R-22 and open its valve to

allow liquid refrigerant to flow in to the system through the
suction 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.

An R410A system will not operate properly with an R-22
metering device.

Install the refrigerant metering device as shown in Figure
1 1. Do not twist cap tubes when loosening the seal nut from
the orifice housing. Use wrench to back up the distributor.

8. Af ter all of the liquid refrigerant has been recovered, switch

the recovery machine to vapor recovery so that all of the R­22 vapor is recovered. Allow the recovery machine to pull a
vacuum on the sytem.

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.

After each system flush, allow the recovery machine to
pull a vacuum on the system at the end of the procedure.

9. Close the valve on the inverted R-22 cylinder and the

gauge set valves. Pump the remaining refrigerant out of
the recovery machine and turn the machine off.

10. Use nitrogen to break the vacuum on the refrigerant

lines and indoor coil before removing the recovery machine,
gauges, and R-22 refrigerant drum. Re-install pressure tap
valve cores into the 4SHP18L T unit’s service valves.

11. Install the fixed orifice (or thermal expansion valve

approved for use with R410A refrigerant) in the liquid line at
the indoor coil.

Refrigerant Metering Device

4HP18LT units are designed for use with TXV systems.
Refer to the appropriate following section for information on
installing the chosen refrigerant metering device.

Figure 10

Expansion Valve Systems

Expansion valves equipped with Chatleff-type fittings are
available from the manufacturer. See Table 3 for proper
TXV for each unit.

TXV Data

MODEL PART NUMBER

4HP18LT- 24

4HP18LT - 36

4HP18LT - 48, -60 H4TXV03

T able 3

To install an expansion valve (See Figure 10 above):

1. Separate the distributor assembly and remove the piston
orifice and used teflon seal. Insert nozzle end of the
expansion valve along with a new teflon seal into the
distributor and tighten to 20 - 30 ft. lbs. Use backup wrench
on all wrench flats. Overtightening will crush the teflon

seal and may cause a leak.

H4TXV01

H4TXV02

506470-01 Issue 1007

2. Attach liquid line portion of distributor assembly along
with new teflon seal to the inlet of the expansion valve.
Tighten to 20 - 30 ft. lbs. Use backup wrench on all wrench
flats. Overtightening will crush the teflon seal and may

cause a leak.

Page 9