Bosch 125B LP 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 LP Specifications

General

Brand	Bosch
Model	125B LP
Category	Water Heater
Type	Tankless
Maximum Temperature	140°F
Energy Factor	0.82
Ignition Type	Electronic
Venting	Direct Vent
Fuel Type	Liquid Propane
Temperature Range	98°F to 140°F

Summary

Installation and Operating Instructions

Specifications

Rules for Safe Operation

Essential safety guidelines for operating the water heater to prevent hazards.

Venting the Heater

Procedures and requirements for proper venting of flue gases for safe operation.

Gas Connections

Detailed steps for making safe and correct gas supply connections to the appliance.

Lighting Instructions

Step-by-step guide for safely lighting the pilot burner.

Maintenance & Service

Trouble Shooting

Common issues, their causes, and solutions for diagnosing and fixing problems.

Safety and Installation Location Guidelines

General Rules for Safe Operation

Outlines essential rules and codes to follow for safe operation and installation.

Proper Location for Installing Your Heater

Combustion Air Requirements and Clearances

Combustion Air Requirements

Details the necessary combustion air supply for proper and safe operation.

Mounting the Heater

Mounting Installation Procedures

Venting the Water Heater

Vertical Gas Vent Requirements

Details requirements for vertical gas vent installation, including height and slope.

Draft Checking and High Altitude Venting

How to Check the Draft

High Altitude Venting Requirements

Specifies requirements for venting at high altitudes, including vent size.

Gas Connections and Pressure Settings

Gas Inlet Pipe and Regulator Installation

Instructions for installing the gas regulator and connecting the gas inlet pipe.

Maximum Inlet Gas Flow Pressure Settings

Gas Piping and Line Sizing

Gas Line Sizing for Natural Gas

Gas Line Sizing for LP Gas

Operating Instructions and Pilot Lighting Safety

Water Connections

Safety Before Lighting the Pilot

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

Heater Operation and Maintenance

Pilot Lighting Instructions

Setting Water Temperature

Troubleshooting Common Issues

Pilot Light Not Lighting

Diagnosing and resolving issues where the pilot light fails to ignite.

Pilot Flame Goes Out

Troubleshooting why the pilot flame extinguishes after the button is released.

Burners Not Igniting

Identifying causes and solutions for main burners failing to ignite.

Pilot Goes Out After Use

Water Too Hot or Too Cold

Temperature Fluctuations / Unit Deactivation