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G–Low Pressure Switch
An auto-reset single-pole single-throw low pressure
switch located in the suction line of the compressor
shuts off the compressor when suction pressure drops
below the factory setting. The switch is normally
closed and is permanently adjusted to trip (open) at 25
+ 5 psi. The switch automatically resets when suction
line pressure rises above 55 + 5 psi. See figure 4 for re-
set switch location.
H–Dual Capacitor
The compressor and fan on all models use permanent
split capacitor motors. A single “dual” capacitor is used
for both the fan motor and the compressor (see unit wir-
ing diagram). The fan side of the capacitor and the com-
pressor side of the capacitor have different mfd ratings.
The capacitor is located inside the unit control box (see
figure 4). Table 2 shows the ratings of the dual capacitor.
TABLE 2
Units
MFD
VAC
HS25 DUAL CAPACITOR RATING
HS25–261
HS25–311
HS25–411, -461
5
30
5
35
5
370
35
Terminal
FAN
HERM
FAN
HERM
FAN
HERM
440
HS25–211
5
25
FAN
HERM
HS25–511
HS25–651
10
40
10
55
FAN
HERM
FAN
HERM
I–Condenser Fan Motor
All units use single–phase PSC fan motors which re-
quire a run capacitor. The “FAN” side of the dual capac-
itor is used for this purpose. The specifications table on
page 1 of this manual shows the specifications of out-
door fans used in HS25s. In all units, the outdoor fan is
controlled by the compressor contactor.
IV–REFRIGERANT SYSTEM
A–Plumbing
Field refrigerant piping consists of liquid and suction
lines from the outdoor unit (sweat connections). Use
Lennox L10 series line sets as shown in table 3 or field
fabricated refrigerant lines. Refer to the piping section
of the Lennox Service Unit Information Manual
(SUI–803–L9) for proper size, type and application of
field–fabricated lines.
Separate discharge and suction service ports are pro-
vided at the compressor for connection of gauge man-
ifold during charging procedure.
Model No.
LIQUID
SUCTION
L10
LINE
LINE
LINE SETS
HS25–261
3/8 in.
5/8 in.
L10–26
20 ft. – 50 ft.
HS25–311
HS25–411
3/8 in.
3/4 in.
L10–41
20 ft. – 50 ft.
HS25–461
HS25-511
3/8 in.
7/8 in.
TABLE 3
HS25–211
3/8 in.
1-1/8 in.
HS25–651
Field Fabricate
L10–65
20 ft. – 50 ft.
B–Service Valves
The liquid line and suction line service valves and
gauge ports are accessible by removing the compres-
sor access cover. Full service liquid and suction line
valves are used. See figures 7 and 8. The service ports
are used for leak testing, evacuating, charging and
checking charge.
KNIFE EDGE SEAL
STEM CAP
SERVICE
PORT CAP
TO LINE
SET
TO
CONDENSER
COIL
LIQUID LINE SERVICE VALVE
IMPORTANT
A schrader valve is not
provided on the liquid line
service port. Valve must
be backseated to turn off
pressure to service port.
FIGURE 7
VALVE STEM
USE SERVICE
WRENCH
(PART #18P66,
54B64 or 12P95)
SERVICE PORT OPEN
TO LINE SET WHEN
FRONT SEATED AND
CLOSED (OFF)
WHEN BACK
SEATED
NO SCHRADER
1 – Liquid Line Service Valve
A full-service liquid line valve made by one of several
manufacturers may be used. All liquid line service
valves function the same way, differences are in
construction. Valves manufactured by Parker are
forged assemblies. Valves manufactured by Primore
are brazed together. Valves are not rebuildable. If a
valve has failed it must be replaced. The liquid line ser-
vice valve is illustrated in figure 7.
The valve is equipped with a service port. There is no
schrader valve installed in the liquid line service port. A
service port cap is supplied to seal off the port.
The liquid line service valve is a front and back seating
valve. When the valve is backseated the service port is
not pressurized. The service port cap can be removed
and gauge connections can be made.
