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A.O. Smith BL-80 - User Manual

A.O. Smith BL-80
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Instruction Manual
PRINTED 1215 324258-002
KEEP THIS MANUAL IN THE POCKET ON HEATER FOR FUTURE REFERENCE
WHENEVER MAINTENANCE ADJUSTMENT OR SERVICE IS REQUIRED.
ULTRA LOW NOX COMMERCIAL GAS WATER HEATERS
For Your Safety
AN ODORANT IS ADDED TO THE GAS USED
BY THIS WATER HEATER.
MODELS BL-80/BL-100
Series 100
INSTALLATION - OPERATION - SERVICE
- MAINTENANCE - LIMITED WARRANTY
PLACE THESE INSTRUCTIONS ADJACENT TO HEATER AND NOTIFY OWNER TO KEEP FOR FUTURE REFERENCE.
Read and understand this instruction
manual and the safety messages
herein before installing, operating or
servicing this water heater.
Failure to follow these instructions and
safety messages could result in death
or serious injury.
This manual must remain with the
water heater.
500 Tennessee Waltz Parkway
Ashland City, TN 37015
Low Lead Content
WARNING: If the information in these
instructions is not followed exactly, a fire
or explosion may result causing property
damage, personal injury or death.
Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other appliance.
WHAT TO DO IF YOU SMELL GAS:
Do not try to light any appliance.
Do not touch any electrical switch; do
not use any phone in your building.
Immediately call your gas supplier
from a neighbors phone. Follow the
gas suppliers instructions.
If you cannot reach your gas supplier,
call the fire department.
Installation and service must be
performed by a qualified installer,
service agency or the gas supplier.

Table of Contents

Questions and Answers

  • K
    kevin41Aug 17, 2025
    Why is my A.O. Smith Water Heater leaking?
    • R
      robertsonjessicaAug 17, 2025
      Water leaks in your A.O. Smith water heater can stem from several causes. One potential reason is improperly sealed connections at the hot or cold supply, relief valve, drain valve, or thermostat threads. Try tightening these threaded connections to resolve the issue. Also, inspect nearby appliances and water lines for leaks that may appear to be coming from the water heater. Condensation may be another cause. In this case, refer to the CONDENSATION section.
  • H
    hsandovalAug 19, 2025
    Why is my A.O. Smith Water Heater not producing enough hot water?
    • A
      Anthony ThompsonAug 19, 2025
      Several factors can cause an A.O. Smith water heater to not produce enough hot water. The heater might not be lit, or the thermostat isn't on. In this case, refer to the LIGHTING INSTRUCTIONS. The thermostat might be set too low (refer to TEMPERATURE REGULATION). The heater could be undersized, so reduce hot water use. Low gas pressure can also be a factor, so contact your gas supplier. If the incoming water is unusually cold, allow more time for the heater to reheat. Leaking hot water pipes or fixtures should be checked and repaired by a plumber. Finally, a high-temperature limit switch may have been activated, in which case you should contact a service technician.
  • C
    Charles JacobsonAug 23, 2025
    Why does my A.O. Smith Water Heater pilot keep going out?
    • C
      Carol ColemanAug 23, 2025
      A pilot outage in your A.O. Smith water heater may be due to several reasons. The pilot burner might be dirty, so clean the pilot assembly. A thermocouple malfunction is another possibility, requiring replacement of the pilot assembly and/or thermocouple. A defective gas control could also be the cause, necessitating replacement of the gas control. Additionally, ensure the thermocouple tip is correctly positioned in contact with the pilot flame; if not, insert the thermocouple correctly.
  • O
    oscar72Aug 26, 2025
    What to do if A.O. Smith BL-80 burner will not stay lit?
    • J
      Jeffrey StoneAug 26, 2025
      If the burner in your A.O. Smith water heater won't stay lit, it could be due to a thermocouple malfunction. Consider replacing the pilot assembly and/or thermocouple. Another potential cause is a defective gas control, which would require replacing the gas control.
  • C
    clarkbryanAug 28, 2025
    Why is my A.O. Smith BL-80's T&P valve leaking?
    • D
      dbranchAug 28, 2025
      A leaking T&P valve in your A.O. Smith water heater can occur due to thermal expansion in a closed water system. Install a thermal expansion tank to resolve this issue and DO NOT plug the T&P valve. It can also happen due to an improperly seated valve. Check the relief valve for proper operation, and again, DO NOT plug the T&P valve.
  • C
    cranetiffanyAug 30, 2025
    Why won't the pilot light on my A.O. Smith BL-80 Water Heater light?
    • M
      mramosAug 31, 2025
      If the pilot on your A.O. Smith water heater won't light, ensure the gas control knob is correctly positioned (refer to LIGHTING INSTRUCTIONS). Also, check that the main gas supply is on and turn on the main gas shutoff valve if necessary. Finally, a thermocouple malfunction could be the cause, requiring replacement of the pilot assembly and/or thermocouple.
  • M
    Mr. Philip DonovanSep 2, 2025
    Why is my A.O. Smith Water Heater water too hot?
    • J
      Jerry BlackSep 3, 2025
      If the water from your A.O. Smith water heater is too hot, the thermostat might be set too high. Refer to the TEMPERATURE REGULATION section for instructions on adjusting it.
  • Z
    Zachary NobleSep 5, 2025
    Why does my A.O. Smith BL-80 smell bad?
    • D
      Diana BrockSep 5, 2025
      Smelly water in your A.O. Smith water heater can be attributed to a high sulfate or mineral content in the water supply. To address this, drain and flush the heater thoroughly, then refill it. Another cause might be bacteria in the water supply, in which case you should chlorinate or aerate the water supply.
  • T
    Tyler SteeleSep 8, 2025
    Why is my A.O. Smith Water Heater making sizzling or rumbling sounds?
    • X
      xmccormickSep 8, 2025
      Sizzling or rumbling sounds in your A.O. Smith water heater are often caused by sediment or calcium buildup in the bottom of the tank. To resolve this, clean the sediment from the tank. Refer to the Draining instructions in the Maintenance section of the manual.
  • J
    Judy MeyersSep 12, 2025
    What causes sooting in an A.O. Smith BL-80?
    • S
      Susan MartinSep 12, 2025
      Sooting in your A.O. Smith water heater is caused by improper combustion. No adjustment is available. Contact a service technician to determine the cause.

Summary

Safe Installation, Use, and Service

Safety Alert Symbol and Definitions

Explains the safety alert symbol and the meanings of DANGER, WARNING, and CAUTION.

Product Approvals and Certifications

Lists AHRI, Low Lead Content, and UL certifications for the water heater.

General Safety Information

Burn Hazards and Hot Water Safety

Warns about burn risks from hot water and provides scald prevention measures.

Fire and Explosion Hazards

Details safety measures against fire, explosion, and gas leaks.

Carbon Monoxide and Ventilation Safety

Addresses carbon monoxide risks and the importance of adequate ventilation.

Property Damage Prevention

Lists precautions to avoid property damage related to water heater operation.

Introduction and Preparation

Abbreviations and Installer Qualifications

Lists abbreviations used and defines requirements for qualified installers.

Installation Preparation Steps

Outlines the initial steps required before performing the installation.

Installation Considerations

Rough-In Dimensions and Specifications

Provides essential physical dimensions for planning the installation.

Recovery Ratings and Performance

Details water heater recovery rates for various temperature rises.

Thermometers and Location Facts

Thermometer Installation and Burn Hazards

Discusses thermometer installation and hot water burn risks.

Location Considerations and Property Damage

Guides on choosing locations and preventing property damage from leaks.

Flammable Vapor Location Risks

Warns about fire/explosion hazards in areas with flammable vapors.

High Altitude and Clearances

High Altitude Carbon Monoxide Risks

Addresses CO hazards and requirements for installations at high altitudes.

Required Installation Clearances

Specifies minimum clearances from combustible materials for safety.

Combustion Air and Ventilation Safety

Emphasizes CO risks and the need for outdoor combustion air.

Insulation, Hard Water, and Pumps

Insulation Blanket Installation Guidelines

Provides instructions and warnings for installing insulation blankets.

Hard Water Treatment Recommendations

Suggests water softening for hard water conditions to protect equipment.

Circulation Pumps

Circulating Pump Wiring Diagrams

Shows electrical hookup diagrams for circulation pumps.

Installation Requirements

Gas Supply System Requirements

Details low and high pressure gas supply system requirements.

Gas Pressure Requirements

Specifies minimum and maximum gas pressure requirements for models.

Supply Gas Regulator Guidelines

Instructs on the proper use and installation of gas supply regulators.

Mixing Valves

DANGER BURN Hazard with Mixing Valves

Warns about burn risks and scald prevention with mixing valves.

Mixing Valve Installation and Use

Guides on selecting and installing mixing valves for temperature control.

Water Piping

WARNING Toxic Chemical Hazard

Warns against connecting to non-potable water systems.

Potable and Space Heating Water Use

Clarifies suitability for potable and space heating applications.

Closed Water Systems

Explains closed water systems and their implications for thermal expansion.

Thermal Expansion

Details the effects of thermal expansion in closed systems.

Temperature-Pressure Relief Valve

WARNING Explosion Hazard

Warns about explosion risks related to temperature-pressure relief valves.

T&P Valve Compliance and Installation

Specifies requirements for T&P valve rating, sizing, and certification.

Temperature-Pressure Relief Valve (Continued)

T&P Valve Safety, Piping, and Testing

Covers discharge piping, burn hazards, and safe operation testing.

Filling the Water Heater

Preventing Damage During Filling

Advises to fill the tank before operation to prevent damage.

Step-by-Step Filling Procedure

Detailed steps for correctly filling the water heater tank.

Air Requirements

Carbon Monoxide and Fresh Air Needs

Reiterates CO risks and the necessity of adequate fresh air.

Air Supply for Confined Spaces

Unconfined vs. Confined Space Air Needs

Defines spaces and specifies air requirements for each.

Direct Vent & Exhaust Fan Air Considerations

Explains how direct vent appliances and exhaust fans affect air supply calculations.

Louvers, Grilles, and Opening Calculations

Factors affecting opening size and methods for calculating required air openings.

Outdoor Air Requirements for Confined Spaces

Outdoor Air Through Horizontal Ducts

Details air intake requirements through two horizontal ducts.

Outdoor Air Through Vertical Ducts

Details air intake requirements through two vertical ducts.

Air From Other Indoor Spaces

Discusses air intake requirements from adjacent indoor spaces.

Venting

WARNING Carbon Monoxide and Venting Hazards

Reinforces carbon monoxide risks related to improper venting.

Venting (Continued)

Vent Dampers

Discusses the use, certification, and removal of vent dampers.

Vent Pipe Sizing and Installation

Guides on correct vent pipe diameter and installation practices.

Vent Pipe Clearances and Fire Hazards

Specifies clearances required between vent pipes and combustible materials.

WARNING Carbon Monoxide Gas Escape

Warns about carbon monoxide escape due to improper venting.

Gas Piping

WARNING Fire and Explosion Hazard

Warns about fire and explosion risks associated with gas piping.

Gas Supply Line Sizing Tables

Provides tables for sizing gas supply lines based on input and length.

Gas Piping Installation and Testing

Details installation, leak testing, and pressure testing of gas piping.

Sediment Trap and Gas Control Connection

Illustrates sediment trap installation and gas control valve connection.

Sediment Traps

Sediment Trap Installation and Purpose

Explains the installation and function of sediment traps in gas lines.

WARNING Fire and Explosion Hazard

Reiterates fire/explosion risks from gas line contaminants.

Safety Before Lighting

General Pre-Lighting Warnings

Provides crucial safety warnings before attempting to light the unit.

What to Do If You Smell Gas

Step-by-step instructions for responding to a gas leak.

Lighting Instructions

Pilot Lighting Procedure

Detailed step-by-step guide for lighting the pilot light.

DANGER Hotter Water Warning

Warns about increased scald risk with hotter water settings.

Temperature Regulation

DANGER BURN Hazard and Scald Prevention

Warns about burn hazards and scald prevention measures.

Setting the Thermostat and Mixing Valves

Guides on adjusting thermostat settings and using mixing valves.

For Your Information

Start Up Conditions

Discusses initial conditions upon starting the water heater.

Condensation Explanation

Explains the causes and effects of condensation in the water heater.

Operational Conditions

Checking Gas Input Rate

Details how to check gas input rate and compare to rating plate.

Smelly Water Causes and Solutions

Explains causes of smelly water and potential solutions.

Hydrogen Gas in Hot Water Faucets

Discusses hydrogen gas risks at hot water faucets and precautions.

High Water Temperature Shut Off System

Explains the automatic high temperature shut-off feature.

Periodic Maintenance

Venting System Inspection

Guides on inspecting the venting system for safety and proper function.

Burner Inspection and Cleaning

Details how to inspect and clean the burner assembly.

Housekeeping Recommendations

Recommends regular cleaning around the water heater base.

Anode Rod Inspection and Testing

Anode Rod Function and Maintenance

Explains anode rod's role in corrosion protection and inspection.

Property Damage Prevention

Advises on preventing water heater damage during maintenance.

Temperature-Pressure Relief Valve

T&P Valve Testing and Safety Hazards

Details T&P valve testing procedures and associated risks.

T&P Valve Compliance and Explosion Risk

Covers T&P valve requirements and explosion hazards.

Lime Deposit Removal Procedure

Lime Formation and Cleaning Recommendations

Discusses lime deposits and their removal from tanks.

Deliming Using Flo-Jug Method

Deliming Solvent Selection (UN LIME)

Recommends UN LIME and provides part numbers for deliming.

Tank Cleanout and Preparation Steps

Details tank cleaning and preparation for the deliming process.

Flo-Jug Kit Preparation and Use

Instructions for preparing and using the deliming transfer kit.

Draining and Flushing

DANGER Burn Hazard during Draining

Warns about burn risks during draining operations.

To Drain the Water Heater Storage Tank

Procedure for draining the water heater tank.

To Flush the Water Heater Storage Tank

Procedure for flushing the water heater tank.

Leakage Checkpoints

Leakage Source Identification

Identifies common sources of water leaks in the water heater.

Checking Threaded Connections for Leaks

Provides steps to check and fix leaks at threaded connections.

Troubleshooting Guidelines

Water Leaks and T&P Valve Issues

Solutions for water leaks and T&P valve problems.

Pilot and Burner Issues

Solutions for pilot not lighting or burner not staying lit.

Hot Water and Sound Issues

Solutions for not enough hot water, too hot, and unusual sounds.

Sooting and Vent Gas Odors

Solutions for sooting and vent gas odors.

Water Piping Diagrams

Single Flue - (1 Unit) Piping Diagram

Illustrates a suggested piping configuration for a single unit.

Water Piping Diagrams (Continued)

Single Flue - (1 Unit) with Vertical Storage Tank

Piping diagram for a unit with a vertical storage tank.

Water Piping Diagrams (Continued)

Single Flue - (1 Unit) with Horizontal Storage Tank

Piping diagram for a unit with a horizontal storage tank.

Water Piping Diagrams (Continued)

Single Flue - (1 Unit) with Mixing Valve

Piping diagram for a unit with a mixing valve and two temperatures.

Water Piping Diagrams (Continued)

Single Flue - (2 Units) Piping Diagram

Piping diagram illustrating two single-flue units.

Water Piping Diagrams (Continued)

Single Flue - (2 Units) Two Temperature

Piping diagram for two units with pre-heater/booster configuration.

Commercial Water Heater Limited Warranty

Warranty Effective Periods

Outlines coverage for tank leaks and part failures.

Whats Covered Under Warranty

Details what is covered under the limited warranty terms.

Whats Not Covered Under Warranty

Lists exclusions from the warranty coverage.

Warranty Limitations and Disclaimers

Specifies limitations and disclaimers of the warranty.

Service Inquiries and Contact Information

Provides information for contacting service support and required details.

A.O. Smith BL-80 Specifications

General IconGeneral
BrandA.O. Smith
ModelBL-80
CategoryWater Heater
LanguageEnglish

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