Unpacking the GWH 425 PN heater
This heater is packed securely.
Before installing the unit, be certain you have the
correct heater for your type of Gas - Propane or
Natural Gas. Identification labels are found on the
shipping box, and on the rating plate which is located on
the right side panel of the cover.
Type of gas
The box includes:
• Pressure relief valve
• Mounting screws
• Product registration card
• Installation manual
• Incandescent particle tray.
Do not lose this manual, there is a charge for a
Please complete and return the enclosed product
The GWH 425 PN is not approved or designed for:
• Manufactured (mobile) homes, RV's or boats
• Heating or other recirculating/pumping applications*
• Solar/preheat backup or high temperature booster
• Installation in a bathroom.
* This includes domestic hot water circulator pump loop
systems that may be installed in home hot water system
prior to installing this unit. An approved recirculation
design can be found in chapter 3.10. Contact BBTNA
if further instruction is needed.
General rules to follow for safe
1. You should follow these instructions when you install
your heater. In the United States: The installation must
conform with local codes or, in the absence of local
codes, the National Fuel Gas Code ANSI Z223.1/
In Canada: The Installation should conform with CGA
B149.(1,2) INSTALLATION CODES and /or local
2. Carefully plan where you install the heater. Proper
clearances must be followed.
3. The appliance must be isolated from the gas supply
piping system by closing its individual manual gas
shutoff valve (not supplied with heater) during any
pressure testing at pressures in excess of ½ Psig (3.5
The appliance and its gas connection must be leak
tested before placing the appliance in operation.
4. Keep water heater area clear and free from
combustibles and flammable liquids. Do not locate the
heater over any material which might burn.
5. Correct gas pressure is critical for the optimum
operation of this heater. Gas piping must be sized to
provide the required pressure at the maximum output of
the heater, while all the other gas appliances are in
operation. Check with your local gas supplier, and see
the chapter 3.7 and 3.8 to verify proper gas line sizing.
6. Should overheating occur or the gas supply fail to
shut off, turn off the gas supply at the manual gas shut
off valve, on the gas line. Note: manual gas shutoff valve
is not supplied with the heater.
7. Do not use this appliance if any part has been
underwater. Immediately call a qualified service
technician to inspect the appliance and to replace any
part of the control system and any gas control which
has been underwater.
BOSCH is constantly improving its
products, therefore specifications are
subject to change without prior notice.
6 720 608 034