User manual BOSCH GWH 425 PN

[. . . ] GWH 425 PN INDOOR MODEL Flow Modulated with Standing pilot Suitable for heating potable water only - Not approved for space heating purposes (Intended for variable flow applications with steady cold water inlet temperatures) GWH-425-PN-N GWH-425-PN-L Warning: If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or death. Do not store or use gasoline or other flammable vapor and liquids in the vicinity of this or any other appliance. Improper installation, adjustment, alteration, service or maintenance can cause injury or property damage. For assistance or additional information consult a qualified installer, service agency or the gas supplier. [. . . ] Loosen the two set screws at the bottom of the water valve where it connects to the gas valve. If the set screws are seized, STOP and call Bosch tech support before proceeding. Forcing and snapping seized set screws may cause irrevocable damage to the water valve and gas valve assemblies. Separate the two halves of the water valve by removing the five screws on the left side of the water valve. Rebuilding the water valve Several parts within the water valve should be replaced every 3 to 5 years depending on water quality and usage. The parts list and instructions can be found on our website at www. boschpro. com. Failure to rebuild the water valve can result in decreased performance or damage to the heater. The GWH 425 PN requires periodic maintenance. The below time maintenance intervals should kept the unit operating for many years. Every year B Inspect inlet water filter screen ( 5. 2) B Inspect pilot assembly and flame ( 5. 3) B Inspect burner assembly ( 5. 4) Every 2 years B Lubricate and clean water valve ( 5. 2) Every 3 to 5 years B Rebuild water valve ( 5. 2) B Clean pilot assembly and clean or replace orifice ( 5. 3) 5. 3 Pilot Inspecting pilot The pilot should burn with a clean sharp blue flame. Cleaning pilot assembly Shut off gas supply to the heater using installer supplied manual gas shutoff. Push upwards on other end of pilot gas tubing to release it from burner mount. Remove brass hex headed pilot orifice from gas valve (located near base of pilot gas tubing). Soak orifice and pilot gas tubing in carburetor cleaner for 30 minutes. Reinstall the pilot gas tubing following removal instructions in reverse. Caution: Do not ream or poke orifice as it will enlarge orifice opening. 5. 2 Water valve The water valve is the main control that tells the heater to fire. If the periodic maintenance is neglected, more costly damage may occur over time. Inspecting inlet water filter screen Shut off the installer supplied cold water isolation valve to the heater. Position a bucket under the heater's water valve assembly to catch any water that may drain from the heater. Remove the filter retaining clip located at base of water valve (see Fig. Lubricating the water valve A more detailed instruction is available on our website at www. boschpro. com. Shut off the installer supplied cold water isolation valve to the heater. Position a bucket under the heater's water valve assembly to catch any water that may drain from the heater. [. . . ] 29 Components Diagram 6 720 608 034 25 Interior components and diagram parts list 8. 3 Item 1 2 3 4 5 6 7 8 9 10 10 11 12 13 14 15 16 17 17 18 19 20 20 21 22 22 23 24 25 26 27 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 Parts list Description Front cover Shield Temp control knob Draft Diverter Exhaust pipe union Ø128 Angle bracket Trade mark badge Heat exchanger Cold water pipe Main burner NG Main burner LP Connector Piezo clip (x10) Sparking plug Pilot gas pipe Tube (x10) Pilot screen Gas valve LP Gas valve NG Throttle housing Washer (x10) Pilot injector LP Pilot injector NG Pilot valve Poppet valve head (2) NG Poppet valve head (3) LP Electromagnet Electromagnet cap Valve operation housing Guide plate Gas pressure regulator LP Gas pressure regulator NG Water valve Watervalve pushrod (10x) Diaphragm (L) Inlet water connection Selector screw Piezo igniter Fixing bracket Ignition lead Thermocouple Flue gas safety device Washer (x10) Heat exchanger washer Threaded bushing Connector Water filter Outlet Hose Water connection clip Plunger Volumetric water governor ECO Temperature limiter Venturi Hot water pipe Gas supply pipe Cover Reference 8 705 431 246 0 8 705 506 817 0 8 702 000 295 0 8 705 505 442 0 8 705 504 046 0 8 708 003 192 0 8 701 103 135 0 8 705 406 275 0 8 700 715 061 0 8 708 120 618 0 8 708 120 619 0 8 705 209 062 0 8 701 201 019 0 8 748 107 089 0 8 700 707 369 0 8 740 609 002 0 8 700 507 067 0 8 707 021 396 0 8 707 021 395 0 8 705 502 067 0 8 701 004 044 0 8 708 200 326 0 8 708 200 327 0 8 708 500 301 0 8 708 500 358 0 8 708 500 359 0 8 707 201 028 0 8 703 305 283 0 8 708 008 069 0 8 701 000 380 0 8 707 406 083 0 8 707 406 084 0 8 707 006 344 0 8 703 204 051 0 8 700 503 084 0 8 700 306 110 0 8 708 500 304 0 8 708 108 051 0 8 701 302 181 0 8 704 401 040 0 8 707 202 083 0 8 707 206 445 0 8 701 004 043 0 8 700 103 658 0 8 700 306 148 0 8 700 306 187 0 8 700 507 059 0 8 700 703 139 0 8 701 201 020 0 8 703 502 039 0 8 705 705 034 0 8 707 206 017 0 8 707 206 132 0 8 708 205 279 0 8 700 715 178 0 8 700 715 351 0 8 705 500 105 0 Table 5 26 6 720 608 034 Fifteen Year Limited Warranty 9 Fifteen Year Limited Warranty costs associated with service, removal or re-installation of the original water heater or a replaced water heater. General BOSCH PRO water heaters are warranted by the Manufacturer (BOSCH) through BBT North America. BBT North America (BBTNA) will furnish a replacement heat exchanger and will furnish a replacement of any other part which fails in normal use and service within the applicable periods specified below, in accordance with the terms of this warranty. The BBTNA replacement will be warranted for the unexpired portion of the original warranty. This warranty will be valid only for water heaters in possession of the original purchaser as recorded on the warranty card. [. . . ]