Applications manual | 13 |
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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
GWH 425 PN Technical Specifications
Power input | Natural Gas: 31,000 - 117,000 BTU |
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| LP Gas: 31,000 - 117,000 BTU |
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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 |
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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 |
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GWH 425 PN Installation Specifications | |
Gas connection | ¾" Male NPT |
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Water connections | ¾" Male NPT |
NG gas pressure | Minimum: 7" W.C. |
| Maximum: 14" W.C. |
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LP gas pressure | Minimum: 11" W.C. |
| Maximum: 14" W.C. |
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Water pressure | Minimum: 30 PSI |
| Maximum: 150 PSI |
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Electrical supply | 120VAC - plugs in |
Vertical venting | 5" minimum diameter - natural |
| draft |
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Horizontal venting | AQ4 horizontal vent kit required |
| for horizontal terminations |
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GWH 425 PN Installation Clearances
Top (A) | 12" |
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Front (B) | 4" |
Back | 0" |
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Sides | 4" |
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Floor (C) | 12" |
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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 |
