Page 6
R
C
W1
Y1
O
G
R
C
W1
W2
W3
G
reversing valve
Outdoor Unit 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 6
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 7
Refrigerant Piping
If the HPXA15 unit is being installed 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 is going to be used to
complete the HPXA15 system, refer to the following sec-
tion which includes flushing procedures.
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.
Refrigerant Connections
HPXA15 Matched with New Indoor Coil and Line Set
If an existing indoor coil which was equipped with an
RFCI metering device is being replaced, the liquid line
must also be replaced prior to the installation of the
HPXA15 unit.
Table 1
Refrigerant Line Sets
M d l
Valve Field Size
Connections
Recommended Line Set
Model
Liquid
Line
Vapor
Line
Liquid
Line
Vapor
Line
L15
Line Sets
−024
−030
−036
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
−042
−048
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
−060
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 50 feet (15
m). For applications longer than 50 feet, consult the Len-
nox Refrigerant Piping Guide (Corp. 9351−L9)
.
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 high−efficiency outdoor unit:
