Lennox LB57113BM Installation Insrtuctions

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INSTALLATION INSTRUCTIONS FOR LOW AMBIENT CONTROL KIT LB-57113BM (27J00)

USED WITH SINGLE-COMPRESSOR HEAT PUMP UNITS

Litho U.S.A.

502,818M
11/98
Supersedes 3/96

®

E1998 Lennox Industries Inc.

Dallas, Texas

LOW AMBIENT CONTROL KIT

KITS COMMON TO HEATING
AND COOLING EQUIPMENT

INSTALLATION INSTRUCTIONS

SHIPPING AND PACKING LIST

Package 1 of 1 contains:

1- Low ambient pressure switch assembly (S11)

1- 36" (914 mm) length of 1/4" (6.35 mm) copper tube

with flare nuts

1- Relay

1- 20ĆFoot length of wire

4- 20" Lengths of wire

1- Bag assembly each containing:

8-Wire nuts

2-Saddle valves

4-#10-16 X 5/8" S.D.S.T. screws

1-Schrader depressor tee with seal cap

APPLICATION

The low ambient pressure switch (S11) cycles the
outdoor fan while allowing compressor operation in the
cooling cycle. This intermittent fan operation results in
a high evaporating temperature which allows the
system to operate without icing the evaporator coil and
losing capacity. This kit is designed for use in ambient
temperatures no lower than 30°F.
Lennox recommends a belly-band style crankcase heater
(P-8-8852, 240v, 45w) be added to compressors which
do not have one. A freezestat (LB-62858CA) should also
be added to any system using a low ambient kit.

NOTE - Do not use this low ambient kit on units with
capillary tube metering devices. Install an expansion
valve metering device if using this kit.

INSTALLATION

A-Pressure Switch Assembly

1- Disconnect power to unit.
2- Remove compressor compartment access panel.
3- Install valve depressor tee discharge line gauge port.
4- Install pressure switch in compressor compartment

with screws provided. Switch should be installed in a
vertical position higher than mid-point of compressor.
See figure 1.

FIGURE 1

TYPICAL INSTALLATION

S11 LOW AMBIENT

PRESSURE SWITCH

HIGH

PRESSURE

SWITCH

COMPRESSOR

DISCHARGE

LINE

S24 LOSS

OF CHARGE

SWITCH

VALV E

DEPRESSOR

TEE

SHOCK

LOOP

5- Connect copper line to low ambient pressure

switch and open side of depressor tee (provided).
Provide a shock loop in copper tubing to prevent
breakage from vibration. Tighten connections.
Depressor tee port with valve core is used as
service port. If necessary, valve core can be moved
to other leg of tee.

B-Low Ambient Pressure Switch Setting (S11)

One of two types of pressure switches are provided. The
Ranco switch has one square and one round adjustment
knob and the Alco switch has two square adjustment
knobs.

Ranco Model

The low ambient pressure switch provided in the kit is
factory set for 285 psig (1965 kPa) cut-in and 140 psig
(965 kPa) cut-out.

If necessary, adjust low ambient pressure switch as
follows:

1-Rotate round knob to set cut-in pressure. Refer to right

set of indicating numbers on face of control. See
figure 3.

2- Rotate square knob to set differential indicator to 145

psig (999 kPa). Refer to left set of indicating numbers.

Alco Model

If necessary, adjust low ambient pressure switch as
follows:

1-Rotate the square knob located on the left to set cut-in

pressure. Refer to left set of indicating numbers on
face of control. See figure 2.

2- Rotate the square knob located on the right to set

differential indicator to 145 psig (999 kPa). Refer to
right set of indicating numbers.

3- Use only terminals 1 and 4 when connecting wiring.

NOTE - Disregard Cut out minus Diff. is Cut In"
statement on face of control. This does not apply in this
application.

C-Low Ambient Relay (K58)

1- Install low ambient relay in control box.

LOW AMBIENT PRESSURE SWITCH S11 DETAIL

RANCO MODEL

ROUND CUT-IN

SQUARE DIFFERENTIAL

ADJUSTMENT KNOB

DIFFERENTIAL

PRESSURE READĆ

OUT ON LEFT

PRESSURE SWITCH IS FACTORY-SET AT 285 PSIG CUT-IN
AND 145 PSIG DIFFERENTIAL (140 PSIG CUT-OUT)

ALCO MODEL

ROUND CUT-IN

ADJUSTMENT

KNOB

SQUARE DIFFERENTIAL

ADJUSTMENT KNOB

ADJUSTMENT

KNOB

CUT-IN PRESSURE

READOUT ON

RIGHT

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CUT-IN PRESSURE

READOUT ON LEFT

DIFFERENTIAL

PRESSURE READĆ

OUT ON RIGHT

FIGURE 2

WIRING

Low ambient pressure switch S11 is wired in series with
outdoor fan relay or compressor contactor (single-stage
or speed units).

S11 LOW AMBIENT CONTROL SWITCHES

OUTDOOR FAN DIRECTLY (LINE VOLTAGE)

TO R" LOW

VOLT

TERM STRIP

K4

DEFROST

RELAY

TO O" LOW
VOLT TERM

STRIP

D

2 31

5 64

8

97

TO K1-1

K31 PIN 5

REMOVE THIS WIRE

Low ambient kits are shown with optional arrows on unit
wiring diagrams. If unit wiring diagram is not available or
does not show the low ambient kit, refer to appropriate
wiring diagram in figures 3 through 13 for wiring
connections.

S11

LOW AMBIENT

PRESSURE

SWITCH

1

4

REMOVE THIS

WIRE

COMP C"

L1

REVERSING

VALV E

K58 LOW
AMBIENT

RELAY

31

64

97

TO 24V COM

FIELD WIRING
FACTORY WIRING

SEE SCHEMATIC FIGURE 4

FIGURE 3

B4

OUTDOOR

FAN MOTOR

TO C12 TERM C

TO K1-1

TO C12

TERMINAL F

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TYPICAL SINGLE-COMPRESSOR HEAT PUMP UNIT WIRING DIAGRAM

(S11 LOW AMBIENT CONTROL SWITCHES OUTDOOR FAN DIRECTLY)

SEE PICTORIAL FIGURE 3

FIGURE 4

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