Bosch Appliances GWH 425 PN/HN4GWH 4254, GWH 260 PN/HN2 manual GWH 425 PN Technical Specifications

Applications manual 13

2.9 Bosch GWH 425 PN

Features:

Standing pilot ignition

78% thermal efficiency

Endless hot water for one major application at a time

Modulating gas valve — constant temperature at varying flow rates Model GWH 425 PN N for natural gas (NG) supply

Model GWH 425 PN L for liquid propane (LP) supply 15-year warranty

GWH 425 PN Technical Specifications

Power input	Natural Gas: 31,000 - 117,000 BTU
	LP Gas: 31,000 - 117,000 BTU
Minimum flow to activate	0.6 gallons per minute (gpm)
Flow rates	45˚F rise @ 4.2 gpm
	55˚F rise @ 3.4 gpm
	65˚F rise @ 2.9 gpm
	77˚F rise @ 2.4 gpm
	90˚F rise @ 2.1 gpm
Thermal Efficiency	NG: 78% LP: 78%
Dimensions	25.75" h x 16.75" w x 8.5" d
Weight	33 lbs.
Modulating gas valve	yes
Ignition	Standing pilot
Accessories	Horizontal vent kit (AQ4) - power
	vent kit for horizontal venting
GWH 425 PN Installation Specifications
Gas connection	¾" Male NPT
Water connections	¾" Male NPT
NG gas pressure	Minimum: 7" W.C.
	Maximum: 14" W.C.
LP gas pressure	Minimum: 11" W.C.
	Maximum: 14" W.C.
Water pressure	Minimum: 30 PSI
	Maximum: 150 PSI
Electrical supply	120VAC - plugs in
Vertical venting	5" minimum diameter - natural
	draft
Horizontal venting	AQ4 horizontal vent kit required
	for horizontal terminations

GWH 425 PN Installation Clearances

Top (A)	12"
Front (B)	4"
Back	0"
Sides	4"
Floor (C)	12"

LIS TED VE NT C AP

MINIMUM 6

FE ET (1.8M)

LIS TED G AS VE NT

E S TAB LIS H A ONE

F OOT R IS E B E F OR E

ANY E LB OW S

Fig. 4 Venting configuration

Installation guidelines:

Venting:

5" minimum diameter — do not reduce vent size. Refer to installation manual for vent material options

Do not combination vent with any power vented appliances.

Establish a one-foot rise before any elbows

Minimum vent height - 6 feet.

Horizontal sections must slope upwards at least ¼" for every foot of the horizontal length and be properly supported.

Gas piping:

Heater will not function properly without adequate supply gas pressure.

Any appliance connector should be ¾" minimum diameter

Plumbing:

Install the included pressure relief valve and pipe to suitable drain.

Minimum piping diameter is ¾".

Do not solder directly to the bottom of the unit. Use full port ball valves for isolation valves.

Bosch Water Heating Applications manual 11.2007