Introduction - A.O. Smith BTH 120 Service And Parts Manual

This service handbook is designed to aid in servicing and troubleshooting A. O. Smith BTH water
heaters in the field. No duplication or reproduction of this book may be made without the express
written authorization of the A. O. Smith Water Products Company.
The following text and illustrations will provide you with a step by step procedure to verify proper
installation, operation and troubleshooting procedures. Additional quick reference data is included to
assist you in servicing this product.
The information contained in this handbook is designed to answer commonly faced situations encoun-
tered in the operation of the BTH product line and is not meant to be all inclusive. If you are
experiencing a problem not covered in this handbook, please contact the A. O. Smith Technical
Information Department at 1-800-527-1953 or your local A. O. Smith Water Products company
representative for further assistance. This handbook is intended for use by licensed plumbing
professionals and reference should be made to the instruction manual accompanying the product.
This handbook contains supplemental information to the BTH instruction manual.
Qualifications: Installation or service of this water heater requires ability equivalent to that of a
licensed tradesman in the field involved. Plumbing, venting, gas supply and electrical testing skills are
required.
Tools Required:
• Phillips head screw driver
• Flat tip screw drivers
• Set of marked drill bits
• Electric multimeter tester
• Gas pressure gauge or manometer (gauge - AOS part number 8099-2)
• Water pressure gauge (AOS part number 4798)
• Draft gauge
• Thermometer (AOS part number 4870 - range 0 thru 220°F)
• 1/2 inch socket with extension for removal of the cleanout
• 1 1/8 inch socket for removal of the anode
• 1 inch socket for hot surface igniter removal
• Pipe wrench for union disconnect
*Note: Also, have a copy of the instruction manual for the model and series BTH
that you are servicing.
Revision 2 includes an added Multiple Venting statement on page 3 and a new Blower Motor Ohms
Resistance Table on page 25. The Pressure Switch Table on page 32 was expanded/revised.
A. O. Smith Water Products Company
Irving, Texas 2000©
BTH HANDBOOK INTRODUCTION
2
Service Handbook
Training Department