Introduction; Qualifications; Service Warning; Service Reminder - A.O. Smith 100 Series Service Handbook

This Service Manual covers the models and series numbers listed on the front cover only. The instructions and illustrations contained
in this manual 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 boiler/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."
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 Manual. If you do not understand the
instructions given in this manual do not attempt to perform any procedures outlined in this manual.
This product requires start-up certification by an qualified service agent that has been trained by the factory for this specific product.
Call 1-800-527-1953 to locate the nearest qualified service agency and arrange a factory certified start-up.

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 manual. If you do not understand the instructions given
in this manual do not attempt to perform any procedures outlined in this manual.

SERVICE REMINDER

When performing any troubleshooting step outlined in this manual 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 REQUIRED

• Instruction Manual that came with the boiler/water heater.
• All hand tools common to installation and service of commercial water heaters and boilers such as torch, pipe wrenches etc.
• TORX® T40 or 5 mm hex wrench - for setting gas mixture at gas valve.
• 3 mm or 7/64 inch hex (Allen) wrench - for setting gas mixture at gas valve.
• 6 mm allen key, Long (8-10") T handle 1/8 inch hex (allen key) wrench for Blower removal and installation.
• Hex (Allen) wrench sizes: 1/2", 5/32", 1/8", 1/4" and 5/16" or TORX® T25/T40 - for Burner, and 24V Gas Valve removal and
installation.
• Two Manometers or Pressure Gauges.
• One - U tube manometer or gauge for measuring supply gas pressure.
• One (optionally two) digital Manometer(s) range -20.00 to +20.00" W.C., resolution 0.01" W.C. Recommend UEI model
EM200, TPI model 620 or equivalent. Used to measure manifold gas pressures and to test performance of pressure
switches. Optional second digital manometer can be used in place of U tube manometer for measuring supply gas
pressures.
• True RMS Digital Multi Meter DMM, recommend UEI model DL289 or Fluke equivalent. Capable of measuring:
• AC/DC Voltage.
• Ohms.
• DC micro amps (μA) - flame sensing current.
• AC amp meter- recommend UEI model DL289 or equivalent.
• Combustion analyzer capable of measuring:
• CO2 (carbon dioxide).
• CO (carbon monoxide).
• Draft Pressure.
• Exhaust Temperature (vent gases).
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INTRODUCTION

Servicing should only be performed by a Qualified Service Agent