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Applications manual | 11.2007Bosch Water Heating
Applications manual
| 13
2.9 Bosch GWH 425 PN
Features:
Standing pilot ignition
78% thermal effi ciency
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 Specifi cations
Power input Natural Gas: 31,000 - 117,000 BTU
LP Gas: 31,000 - 117,000 BTU
Minimum fl ow 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 Effi ciency 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 Specifi cations
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"
LISTED VENT CAP
MINIMUM 6
FEET (1.8M)
LISTED GAS VENT
ESTABLISH A ONE
FOOT RISE BEFORE
ANY ELBOWS
Fig. 4 Venting confi guration
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.