Bosch GWH 425 EF User Manual

Water heaters for use with Natural and L.P.G.
GWH 425 EF
Flow Modulated with Electronic Ignition and Power Venting
Suitable for heating potable water only - Not approved for space heating purposes
(Intended for variable flow applications with steady cold water inlet temperatures)
GWH-425-EF-N
GWH-425-EF-L
6 720 607 017 US (04.10) 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 must be installed 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. Open windows.
• 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 GWH 425 EF Specifications

General

Type	Tankless
Fuel Type	Gas
Gas Type	Natural Gas / Propane
Energy Factor	0.82
Thermal Efficiency	82%
Ignition Type	Electronic Ignition
Venting	Direct Vent
Flow Rate	4.2 GPM
Energy Efficiency Rating	Energy Star
Gas Connection	3/4" NPT
Water Connection	3/4" NPT

Summary

Safety Precautions

General Warnings

Critical safety information regarding installation, operation, and potential hazards.

Gas Leak Response

Procedure to follow in case of smelling gas, emphasizing immediate safety actions.

Installation Clearances

Views and Diagrams

Diagrams illustrating front and side views, and minimum clearances for alcove/closet installations.

Gas Connections

Gas Line Sizing

Guidelines for selecting appropriate pipe sizes for natural gas and LP gas lines based on length and BTU input.

Water Connections

Pressure Relief Valve (PRV) Installation

Instructions for installing the pressure relief valve, including placement and discharge line requirements.

Operating Instructions

Lighting and Operation

Detailed steps for igniting the pilot and main burners and operating the appliance.

Setting Water Temperature

Instructions on how to adjust the temperature selector knob for desired hot water output.