Bosch Pro Tankless GWH-425-HNO-N User Manual

GWH 425 HNO OUTDOOR MODEL
For exterior use only
Electronic Ignition
Suitable for heating potable water only - Not approved for space heating purposes
GWH-425-HNO-N - Natural Gas
GWH-425-HNO-L - Liquefied Petroleum (LP) Gas
8 716 473 148 US (05.12) AL
Warning: If the information in this manual 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
vapor and liquids in the vicinity of this or any other
appliance.
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.
In the Commonwealth of Massachusetts this
product is approved only for seasonal use.
Installation must be performed by a licensed
plumber or gas fitter.
Upon completion of the installation, these
instructions should be handed to the user of the
appliance for future reference.
What to do if you smell gas
• Close gas valve.
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any
phone in your building.
• If you cannot reach your gas supplier, call the fire
department.
• Immediately call your gas supplier from a neighbor’s
phone. Follow the gas supplier’s instructions.
• Installation and service must be performed by a
qualified installer, service agency or the gas supplier.

Bosch Pro Tankless GWH-425-HNO-N Specifications

General

Type	Tankless
Brand	Bosch
Model	GWH-425-HNO-N
Fuel Type	Natural Gas
Maximum Temperature	140°F
Energy Efficiency	82%
Minimum Activation Flow	0.5 GPM
Warranty	15 years heat exchanger, 5 years parts

Summary

Warning and Safety Information

General Safety Precautions

Covers crucial safety precautions for operating and installing the water heater, including warnings about fire and explosion risks.

Gas Leak and Flammable Vapor Dangers

Provides guidance on handling gas leaks and the dangers of flammable vapors near the appliance, emphasizing immediate actions.

Appliance Details

Technical Specifications

Installation Instructions

Location, Clearances, and Mounting

Gas Piping and Connections

Details gas supply line requirements, connections, high altitude adjustments, and sizing, plus leak detection.

Gas Pressure and Water Connections

Electrical Connections

Specifies electrical requirements, grounding, and power supply connections for the heater, adhering to codes.

Operation Instructions

Safety Procedures and Gas Detection

Provides critical safety guidelines and steps to take if a gas leak is detected before or during operation.

Lighting, Shut-off, and Temperature Setting

Maintenance and Service

Troubleshooting

Pilot and Burner Ignition Issues

Provides solutions for when the pilot will not light or burners fail to ignite or stay lit.

Water Temperature and Flow Problems

Addresses issues with fluctuating temperatures, water being too hot, or not hot enough.

Fifteen Year Limited Warranty

Warranty Terms and Claims