Introduction; Qualifications; Service Warning; Service Reminder - A.O. Smith BTR 120-400 Service Handbook

INTRODUCTION

This Service Handbook covers the water heater Model and Series numbers listed on the front cover only.
The instructions and illustrations contained in this service handbook will provide you with troubleshooting
procedures to verify proper operation and diagnose and repair common service problems.

QUALIFICATIONS

QUALIFIED INSTALLER OR SERVICE AGENCY
Installation and service of this water heater requires ability equivalent to that of a Qualified Agency (as defined
by ANSI below) in the field involved. Installation skills such as plumbing, air supply, venting, gas supply and
electrical supply are required in addition to electrical testing skills when performing service.
ANSI Z223.1 2006 Sec. 3.3.83: "Qualified Agency" - "Any individual, firm, corporation or company that either
in person or through a representative is engaged in and is responsible for (a) the installation, testing or
replacement of gas piping or (b) the connection, installation, testing, repair or servicing of appliances and
equipment; that is experienced in such work; that is familiar with all precautions required; and that has
complied with all the requirements of the authority having jurisdiction."

SERVICE WARNING

If you are not qualified (as defined by ANSI above) and licensed or certified as required by the authority
having jurisdiction to perform a given task do not attempt to perform any of the procedures described in this
service handbook. If you do not understand the instructions given in this service handbook do not attempt to
perform any procedures outlined in this service handbook.

SERVICE REMINDER

When performing any troubleshooting step outlined in this service handbook always consider the wiring
and connectors between components. Perform a close visual inspection of all wiring and connectors to and
from a given component before replacement. Ensure wires were stripped before being crimped in a wire
connector, ensure wires are crimped tightly in their connectors, ensure connection pins in sockets and plugs
are not damaged or worn, ensure plugs and sockets are mating properly and providing good contact.
Failure to perform this critical step or failing to perform this step thoroughly often results in needless down
time, unnecessary parts replacement, and customer dissatisfaction.

TOOLS RECOMMENDED

• Instruction Manual that came with the water heater.
• All tools common to installation and service of commercial water heaters such as hand tools, screwdrivers,
pipe wrenches etc.
• Hex (Allen) wrench sizes: 5/32", 1/8", 1/4" and 5/16"
• Digital manometer: Range -20.00 to +20.00" W.C. Resolution - 0.01" W.C. Required to test supply gas
pressure.
• Digital Multi Meter; capable of measuring:
• AC/DC Voltage.
• Ohms.
• DC micro amps (μA).
2 Servicing should only be performed by a Qualified Service Technician