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

1 2 Applications manual

2.8 Bosch GWH 425 HN

Features: Hydro-generated ignition 80% thermal efficiency

Endless hot water for one major application at a time Venting: 5" double wall B-vent — natural draft

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

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

Qualifies for $300 tax credit

GWH 425 HN Technical Specifications

Gas input	Natural Gas: 30,735 - 117,000 BTU
	LP Gas: 30,735 - 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: 80% LP: 80%
Dimensions	25.75" h x 16.75" w x 8.5" d
Weight	33 lbs.
Modulating gas valve	yes
Ignition	Hydro-generated
Accessories	Horizontal vent kit (AQ4) - power
	vent kit for horizontal venting
GWH 425 HN 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
(Static)	Minimum well pressure: 40 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 HN 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. 2 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 connections on the bottom of the unit Use full port ball valves for isolation valves

Application manual 11.2007 Bosch Water Heating