Bosch 125B NG User Manual

WARNING: Improper installation, adjustment,
alteration, service or maintenance can cause injury or
property damage. Refer to this manual. For assistance
or additional information consult a qualified installer,
service agency or the gas supplier.
Upon completion of the installation, these instructions
should be handed to the user of the appliance for future
reference.
In the Commonwealth of Massachusetts this product
must be installed by a licensed plumber or gas fitter.
INSTALLATION AND OPERATING INSTRUCTIONS FOR AUTOMATIC
INSTANTANEOUS TYPE WATER HEATERS FOR USE WITH NATURAL AND
LIQUEFIED PETROLEUM GAS
MODEL 125B LP and 125B NG (Flow Modulated)
Suitable for heating potable water only
Not approved for space heating purposes
Intended for variable flow applications with steady cold water inlet temperatures only
WARNING
If the information in this manual is not followed exactly, a
fire or explosion may result causing property damage,
personal injury or death.
FOR YOUR SAFETY
Do not store or use gasoline or other flammable,
combustible or corrosive 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 neighbor’s
phone. Follow the gas supplier’s 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.
Specifications....................................... Page 2
Rules for safe operation ..................... Page 4
Locating the Heater ............................ Page 4
Combustion Air Requirements .......... Page 5
Mounting the Heater ........................... Page 6
Venting the Heater .............................. Page 7
Gas Connections ..............................Page 10
Water Connections ...........................Page 12
Safety before lighting the pilot .......Page 12
Lighting instructions ..........................Page 13
Setting water temperature ...............Page 13
Maintenance & Service ....................Page 13
Trouble Shooting................................Page 14
Diagram of AquaStar ........................Page 19
Components and Parts List ............ Page 20
Warranty ............................................. Page 22
TABLE OF CONTENTS
6 720 607 030 US (05.12) AL

Bosch 125B NG Specifications

General

Brand	Bosch
Model	125B NG
Category	Water Heater
Language	English

Summary

Introduction and Safety

For Your Safety

Essential safety precautions for operating the water heater and general warnings.

What To Do If You Smell Gas

Immediate actions to take if a gas leak is detected to prevent fire or explosion.

Product Specifications and Features

AquaStar 125B LP and 125B NG Specifications

Technical data and specifications for the AquaStar 125B models, including input and pressure.

Features

Key benefits and design aspects of the AquaStar water heater, such as material and efficiency.

Unpacking the Aquastar Heater

Instructions and components included with the Aquastar heater package.

Installation Guidelines

General Rules to Follow for Safe Operation

Essential safety rules and precautions for installing and operating the heater.

Proper Location for Installing Your Heater

Guidelines for selecting the correct and safe location for the water heater.

Combustion Air Requirements

Specifications for ensuring adequate combustion and ventilation air supply.

Clearances

Minimum distances required from combustible and non-combustible materials.

Mounting Installation

Instructions and recommendations for securely mounting the water heater on a wall.

Venting Procedures

Venting

Detailed requirements for venting the water heater to the outside.

Vertical Gas Vent

Guidelines for vertical gas vent installation, including pipe size and height.

Masonry Chimney Venting

Requirements for connecting the heater to masonry chimneys.

Gas and Water Connections

Gas Connections

Instructions and guidelines for connecting the gas supply line.

Gas Line Sizing

Recommendations for sizing gas pipes for Natural Gas and LP Gas.

Water Connections

Details on how to connect the water inlet and outlet pipes to the heater.

Operation, Lighting, and Temperature Control

Connecting the Pressure Relief Valve (PRV)

Instructions for installing the pressure relief valve (PRV) correctly.

Operating Instructions

Steps to follow before and during the initial operation of the heater.

Safety Before Lighting the Pilot

Crucial safety checks and warnings before attempting to light the pilot.

Lighting Instructions

Step-by-step guide for lighting the pilot and main burners.

Setting Water Temperature

How to adjust the water temperature control knob and gas control slide.

Maintenance and Troubleshooting

Maintenance and Service

Recommended schedule and procedures for maintaining the water heater.

Trouble Shooting

Common problems and their solutions for the AquaStar water heater.

Pilot Light Will Not Light

Common causes and solutions when the pilot light fails to ignite.

Pilot Lights But Flame Goes Out

Troubleshooting steps if the pilot flame extinguishes after release.

Burners Do Not Ignite

Reasons why the main burners may not ignite when hot water is used.

Pilot Light Goes Out During or After Use

Diagnosing issues where the pilot light extinguishes during or after operation.

Water Is Too Hot

Adjusting settings to lower the hot water temperature output.

Water Is Not Hot Enough

Troubleshooting low hot water temperature issues.

Hot Water Temperature Fluctuates / Unit Deactivated

Addressing issues with unstable or fluctuating hot water temperatures.

Diagrams and Parts Identification

Diagram of AquaStar 125B

Visual representation of the AquaStar 125B water heater's external components.

Interior Components Diagram and Parts List

Detailed diagram and list of internal parts of the AquaStar 125B.

Warranty and Support

Limited Warranty

Details of the warranty coverage, including heat exchanger and other parts.

Service Labor Costs

Information regarding labor costs not covered by the warranty.

How to Make a Claim

Procedure for submitting a warranty claim for parts or replacement.