Page 5
R
C
W1
Y1
O
G
R
C
W1
W2
W3
G
reversing valve
HPXA12 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 auxiliary 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 t’stat
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 proce-
dures.
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-fabri-
cated 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, re-
place the liquid line prior to installing the HPXA12 unit.
See table 1.
Table 1
Refrigerant Line Sets
Valve Field Size
Connections
Recommended Line Set
Model
Liquid
Line
Vapor
Line
Liquid
Line
Vapor
Line
L15
Line Sets
−18
−24
−30
3/8 in.
(10 mm)
3/4 in.
(19 mm)
3/8 in.
(10 mm)
3/4 in.
(19 mm)
L15−41
15 ft. − 50 ft.
(4.6 m − 15 m)
−36
−42
−48
3/8 in.
(10 mm)
7/8 in.
(22 mm)
3/8 in.
(10 mm)
7/8 in.
(22 mm)
L15−65
15 ft. − 50 ft.
(4.6 m − 15 m)
−60
3/8 in.
(10 mm)
1−1/8 in.
(29 mm)
3/8 in.
(10 mm)
1−1/8 in.
(29 mm)
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 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.
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