Lennox 12HPB Series

Page 1
©1997 Lennox Industries Inc.
Corp.9504-L1
12HPB
Service Literature
Revised 10-2004
12HPB SERIES UNITS
The 12HPB is a residential split-system heat pump. The
series is designed for use with expansion valves (TXV). All
12HPB units utilize scroll compressors.
Information contained in this manual is intended for use by
qualified service technicians only. All specifications are subject
to change.
This manual is divided into sections which discuss the
major components, refrigerant system, charging proce-
dure, maintenance and operation sequence.
12HPB series units are available in 2, 2 -1/2, 3, 3 -1/2, 4
and 5 ton capacities. All major components (indoor blower
and coil) must be matched according to Lennox recom-
mendations for the compressor to be covered under war-
ranty. Refer to the Engineering Handbook for approved
system matchups.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect electronic
components. Take precautions during unit instal-
lation and service to protect the unit’s electronic
controls. Precautions will help to avoid control
exposure to electrostatic discharge by putting
the unit, the control and the technician at the
same electrostatic potential. Neutralize electro-
static charge by touching hand and all tools on an
unpainted unit surface before performing any
service procedure.
WARNING
Refrigerant can be harmful if it is inhaled. Refriger-
ant must be used and recovered responsibly.
Failure to follow this warning may result in person-
al injury or death.
SPECIFICATIONS
Model No. 12HPB24 12HPB30 12HPB36
Net face area sq ft (m
2
)
Outer coil 15.21 (1.41) 15.21 (1.41) 15.21 (1.41)
Outdoor
Net face area - sq. ft. (m
2
)
Inner coil 5.44 (0.51) 14.50 (1.35) 14.50 (1.35)
Outdoor
Coil
Tube diameter  in. (mm) & no. of rows 5/16 (8)  1.37 5/16 (8)  2 5/16 (8)  2
Fins per inch (m) 18 (709) 22 (866) 22 (866)
Diameter  in. (mm) & no. of blades 18 (457)  3 18 (457)  4 18 (457)  4
Outdoor
Motor hp (W) 1/6 (124) 1/6 (124) 1/6 (124)
O
u
td
oor
Coil
F
Cfm (L/s) 2500 (1180) 2450 (1155) 2450 (1155)
Fan
Rpm 1100 1100 1100
Watts 200 200 200
*Refrigerant charge furnished (HCFC-22) 6 lbs. 14 oz. (3.11 kg) 7 lbs. 14 oz. (3.56 kg) 8 lbs. 1 oz. (3.64 kg)
Liquid line  in. (mm) o.d. connection (sweat) 3/8 (9.5) 3/8 (9.5) 3/8 (9.5)
Vapor line  in. (mm) o.d. connection (sweat) 3/4 (19.1) 3/4 (19.1) 7/8 (22.2)
Shipping weight  lbs. (kg) 1 package 162 (73) 181 (82) 187 (85)
*Refrigerant charge sufficient for 15 ft. (4.5 m) length of refrigerant lines.

Lennox 12HPB Series Specifications

General

Brand	Lennox
Model	12HPB Series
Category	Heat Pump
Language	English

Summary

12 HPB Series Unit Overview

Electrostatic Discharge (ESD) Precautions

Safety measures to protect electronic components from static discharge during installation and service.

Series Unit Specifications

Technical details and dimensions for the 12HPB series outdoor units.

Unit Specifications and Electrical Data

Outdoor Coil and Unit Specifications

Technical data for outdoor coil dimensions, tubing, fins, motor, and refrigerant charge.

Electrical Data

Electrical ratings, voltage, amps, and fuse/breaker sizes for 12HPB units.

Unit Components

12 HPB Unit Components Diagram

Illustration showing major components of the 12HPB unit, including control box.

Control Box Details

Explanation of the control box, compressor contactor (K1), and dual capacitor (C12).

Defrost System (Pre-April 2002)

Defrost Thermostat Function

Role of the defrost thermostat in initiating and terminating defrost cycles.

Defrost Control Board Operation

Details on timing pins, time-delay, pressure switch circuit, and diagnostic LEDs.

Defrost System (April 2002 and Later)

Defrost Thermostat Operation

Operation of the defrost thermostat for newer unit versions.

Defrost Control Board Features

Details on defrost control board, wiring connections, timing, pressure switches, and diagnostics.

Compressor Description

Scroll Compressor Operation

Explanation of the scroll compressor design, operation, and properties.

Outdoor Unit Components

Outdoor Fan Motor

Details on the single-phase PSC fan motors used in 12HPB units.

Reversing Valve and Solenoid

Explanation of the electromechanical solenoid reversing valve.

Refrigerant System

Refrigerant System Components

Diagram and identification of key refrigerant system components.

Cooling Cycle Operation

Diagram illustrating the 12HPB cooling cycle with gauge connections.

Heating Cycle Operation

Diagram illustrating the 12HPB heating cycle with gauge connections.

Plumbing and Line Sets

Line Set Specifications

Table detailing Lennox line set model numbers, lengths, and pipe sizes.

Service Valve Operation

Instructions for operating liquid and vapor line service valves.

Charging Procedures

Pumping Down System

Procedure for pumping down the system to check for leaks or make repairs.

Leak Testing

Methods for leak testing the refrigerant lines and indoor coil.

Evacuating the System

Steps for evacuating the system to the required vacuum level.

Charging Methods

Approach Method (TXV Systems)

Procedure for charging using ambient and liquid line temperatures.

Subcooling Method (TXV Systems)

Procedure for charging using liquid line pressure and temperature.

Maintenance

Outdoor Unit Maintenance

Cleaning and inspection of the condenser coil and connections.

Indoor Coil Maintenance

Cleaning and inspection of the indoor coil and condensate line.

Indoor Unit Checks

Checking filters, wiring, voltage, and amp-draw on the indoor unit.

Low Voltage Field Wiring

Wiring for CB19 CBH19 ECB19 Units

Field wiring diagram for 12HPB units with specific blower coils and thermostats.

Wiring for B24 ECB24 Units

Field wiring diagram for 12HPB units with B24/ECB24 blower coils and thermostats.

Wiring Diagram and Sequence of Operation

12 HPB Wiring Diagram

Schematic showing electrical connections for 12HPB 2 through 5 ton units.

Operating Sequence

Step-by-step explanation of unit operation in cooling, heating, and defrost modes.