Bosch GWH 425 HN
Bosch GWH 425 Hn Freezer, size: 832 KB
Bosch GWH-425-HN-N Tankless Water Heater, Indoor Use Ideal for households looking to maximize energy savings. New homeowners want the energy-efficient, endless supply of hot water only a gas tankless water heater can deliver. Elegantly engineered, these units are small, lightweight, and easy to install and maintain. Patented Bosch Hydro-Generated Ignition Technology. The Bosch engineers have proven that water can indeed make fire. The pilot is ignited by a super-concentrated spark generated by a... Read more
Part Numbers: GWH 425 HN N, GWH-425-HN-N, GWH425HNN
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User reviews and opinions
|sshriner1||8:28am on Saturday, June 5th, 2010|
|A change, & good replacement for the tank system. We replaced an electric 30 gallon hot water tank for this natural gas unit. The obvious difference,...|
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IAPMO Research and Testing, Inc. is a product certification body which tests and inspects samples taken from the supplier's stock or from the market or a combination of both to verify compliance to the requirements of applicable codes and standards. This activity is coupled with periodic surveillance of the supplier's factory and warehouses as well as the assessment of the supplier's Quality Assurance System. This listing is subject to the conditions set forth in the characteristics below and is not to be construed as any recommendation, assurance or guarantee by IAPMO Research and Testing, Inc. of the product acceptance by Authorities Having Jurisdiction.
Effective Date: Product: Issued To:
Void After: January 2011 File No. 6710
California Lead Plumbing Law Devices and Components Bosch Termotecnologia S.a. En16-km3,7 Aveiro, 3800-533 CACIA Portugal
Each fitting shall bear permanent and legible markings to identify the manufacturer. This marking shall be the trade name, trademark, or other mark known to identify the manufacturer. The product may also bear the term "California Lead Plumbing Law" or "Complies with California Lead Plumbing Law" above or in close proximity to the appropriate IAPMO R&T certification mark and if the products meet requirements of the Uniform Plumbing Code.
Plumbing products to be installed in accordance with the manufacturer's instruction. Manufactured in compliance with Section 116875 of the California Health & Safety Code and the Vermont's Lead Reduction Law. Products listed on this certificate have been tested by an IAPMO R&T recognized laboratory. 17025. This recognition has been granted based upon the laboratorys compliance to the applicable requirements of ISO/IEC
For the most accurate and updated information please visit http://pld.iapmo.org/6710
Page 2 -Rev. 7/23/2010Product: Issued To: MODELS: Model No. GWH 715 CTD R EFS LPG GWH 715 CTD R EFS NG GWH C 800 CTD R EFS LPG GWH C 800 CTD R EFS NG GWH 2400 CTD R EFS LPG GWH 2400 CTD R EFS NG GWH 2700 CTD R EFS LPG GWH 2700 CTD R EFS NG Integra 500 NG Integra 500 LPG Evolution 500 LPG Evolution 500 NG GWH 1000 P LP GWH 1000 P NG GWH 1600 P LP GWH 1600 P NG GWH 1600 H LP GWH 1600 H NG GWH 1600 PS LP GWH 1600 PS NG GWH 260 PN N GWH 260 PN L GWH 425 HN L GWH 425 HN N GWH 425 PN L GWH 425 PN N GWH 425 PS L GWH 425 PS N GWH C 920 CTD R EFS LP GWH C 920 CTD R EFS NG GWH C 920 CTD RC EFS LP GWH C 920 CTD RC EFS NG C 1210 ESC NG C 1210 ESC LP C 1210 ES NG C 1210 ES LP C 1050 ES NG C 1050 ES LP 940 ES NG 940 ES LP 940 ESO NG 940 ESO LP 520 HN NG 520 HN LP 520 PN NG Description Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall Gas fired wall hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang hang instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous instantaneous water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water water heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater heater California Lead Plumbing Law Devices and Components Bosch Termotecnologia S.a. Void After: January 2011 File No. 6710
Page 3 -Rev. 7/23/2010Product: Issued To: 830 PN PN PN ES ES LP NG LP NG LP California Lead Plumbing Law Devices and Components Bosch Termotecnologia S.a. Gas Gas Gas Gas Gas fired fired fired fired fired wall wall wall wall wall hang hang hang hang hang instantaneous instantaneous instantaneous instantaneous instantaneous water water water water water heater heater heater heater heater Void After: January 2011 File No. 6710
Page 4 -Rev. 7/23/2010Product: Issued To: California Lead Plumbing Law Devices and Components Bosch Termotecnologia S.a. Void After: January 2011 File No. 6710
ADDITIONAL COMPANY INFO:
Water heaters for use with Natural and L.P.G.
GWH 425 HN
Flow Modulated with Electronic Ignition Suitable for heating potable water only - Not approved for space heating purposes (Intended for variable flow applications with steady cold water inlet temperatures)
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. Refer to this manual. For assistance or additional information consult a qualified installer, service agency or the gas supplier. In the Commonwealth of Massachusetts this product must be installed by a licensed plumber or gas fitter. Upon completion of the installation, these instructions should be handed to the user of the appliance for future reference. What to do if you smell gas Close gas valve. Open windows. Do not try to light any appliance Do not touch any electrical switch; do not use any phone in your building If you cannot reach your gas supplier, call the fire department. Immediately call your gas supplier from a neighbors phone. Follow the gas suppliers instructions. Installation and service must be performed by a qualified installer, service agency or the gas supplier.
US (04.11) AL
TABLE OF CONTENTS WARNING : Improper installation, adjustment, alteration, service or maintenance can cause injury or property damage. Refer to this manual. For assistance or additional information consult a qualified installer, service agency or the gas supplier. Upon completion of the installation, these instructions should be handed to the user of the appliance for future reference. In the Commonwealth of Massachusetts this product must be installed by a licensed plumber or gas fitter.
Specifications... Page 3 Rules for safe operation... Page 5 Locating the Heater... Page 5 Combustion Air Requirements.. Page 6 Mounting the Heater.. Page 6 Venting the Heater.. Page 7 Gas Connections.. Page 9 Gas Piping... Page 10 Water Connections.. Page 11 Safety before turning on the heater.. Page 11 Operating instructions.. Page 12 Setting water temperature.. Page 12 Maintenance & Service.. Page 13 Trouble Shooting.. Page 13 Electrical Diagram.. Page 15 Diagram of 425HN... Page 17 Interior components diagram. Page 18 Parts List... Page 19 Flowchart... Page 20 Warranty... Page 21
If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or death.
FOR YOUR SAFETY
Do not store or use gasoline or other flammable, combustible or corrosive vapors and liquids in the vicinity of this or any other appliance.
WHAT TO DO IF YOU SMELL GAS
- Do not try to light any appliance. - Do not touch any electrical switch; do not use any phone in your building. - Immediately call your gas supplier from a neighbors phone. Follow the gas suppliers instructions. - If you cannot reach your gas supplier, call the fire department. - Installation and service must be performed by a qualified installer, service agency or the gas supplier.
Principle of Operation: When a hot water faucet is opened, the water flow through the heater causes the gas valve to open. At the same time the hydro-generator activates the electronics which sends a spark to the pilot. The flame sensor confirms the pilot has been lighted and allows the first two burners to come on. The flame sensor confirms correct activation and all burners come on. The pilot goes off. The heat exchanger coils absorb the heat generated by the burners and transfer heat to the water. When the hot water faucet is shut off, the gas valve automatically closes and the burners turn off. Your hot water faucet is an ignition key to activate the water heater, giving you control over your hot water energy use. Every time you turn off your hot water faucet, the energy consumption of your hot water returns to zero.
The heater may still operate even when improperly vented. It will, however, be less efficient and could eventually damage the heater. It could even result in human sickness or death due to oxygen deprivation and carbon monoxide poisoning. Follow the guidelines below: 1. Place your heater as close to a vent or chimney as possible. 2. National building codes require that you do not install this appliance in bathrooms, bedrooms or any occupied rooms normally kept closed. 3. Simultaneous operation of other appliances such as exhaust fans, ventilation systems clothes dryers, fireplaces or wood stoves could create a vacuum effect in your home which could cause dangerous combustion by-products to spill back into your home rather than venting to the outside through the flue. Confirm that your 425 HN is venting properly when all these other appliances are running. See section on venting. Do not obstruct the flow of combustion and ventilation air to the appliance. If installed near a clothes dryer it is very important that the dryer be properly vented. Failure to properly vent a dryer could result in a gradual accumulation of lint on the water heater fin coils and burners, leading to a dangerous condition of vent blockage and poor unsafe combustion. 4. Your hot water lines should be kept short to save energy. It is always best to have hot water lines insulated. 5. This product is neither designed nor approved for outside installations. This product is not approved for manufactured homes (mobile home), recreational vehicles (RV) or boats. Reference ANSI Z21.10.3. WARNING: The water in this water heater is cold and always remains cold except for the times that hot water is being used DO NOT INSTALL IN AN AREA WHERE IT COULD FREEZE. This heater is neither designed for nor approved for outside installation. Drain the heater entirely if freezing temperatures are anticipated in area where heater is installed by disconnecting both the inlet and outlet water connections from the heater (disconnect the outlet flex line from where it connects to the copper heat exchanger). Additionally remove the drain plug under the water valve. See Fig. 1.
PROPER LOCATION FOR INSTALLING YOUR HEATER
Carefully select the location of your new heater. For your safety and for proper heater operation, you must provide an abundant supply of combustion air and a proper venting.
Fig. 1 - Water heater drain plug
WARNING: Flammable materials, gasoline, pressurized containers, or any other items or articles that are potentially fire hazards must NOT be placed on or adjacent to the heater. The appliance area must be kept free of all combustible materials, gasoline and other flammable vapors and liquids.
COMBUSTION AIR REQUIREMENTS
The 425 HN water heater holds cold water in its copper heat exchanger and brass water valve when not in use. Because of this, any cold air that comes down through the units vent pipe is capable of freezing these components. This Installation Manual specifies the minimum vertical vent pipe and the amount of combustion air required for this unit. When all requirements are followed, the unit will operate properly and safely. However, there may still be a risk of freezing due to negative draft if all the combustion appliances in the area are not being supplied with a sufficient amount of make-up air. A wood stove or furnace may pull combustible air down through the 425 HN vent system, leaving the cold infiltrating air capable of freezing the cold water in the 425 HN heat exchanger. More make up air is the solution. Follow the instructions on venting and checking adequacy of make up air. A HVAC specialist should be used to design solutions for providing more make-up air if necessary. Observe the following instructions concerning combustion air. Appliances located in unconfined spaces: a) An unconfined space is one whose volume is greater than 50 cubic feet per 1000 Btu per hour of the combined rating of all appliances installed in the space. That would be 5850 cubic feet for the 425HN alone. b) In unconfined spaces in buildings of conventional frame, masonry, or metal construction, infiltration is normally adequate to provide air for combustion, ventilation, and dilution of flue gasses.
Appliances located in confined spaces: The confined space must be provided with two permanent openings, one commencing within 12 inches of the top and one commencing within 12 inches of the bottom of the enclosure. Each opening must have a minimum free area of one square inch per: - 1000 Btu/hr if all air is taken from inside the building. - 2000 Btu/hr if all air is taken from the outside by horizontal ducts. - 4000 Btu/hr if all air is taken from the outside by direct openings or vertical ducts. Or the confined space must be provided with one permanent opening or duct that is within 12 inches of the ceiling of the enclosure. This opening must have a minimum free area of one square inch per: - 3000 Btu/hr if all air is taken from the outside by a direct opening or vertical duct. Louvers, grills and screens have a blocking effect. If the effective free area is not known, increase the sizes of your openings by 75% if your louvers are wood and by 30% if your louvers are metal. Refer to the National Fuel Gas Code for complete information. In buildings of tight construction all air should be taken from outside.
The 425 HN is design certified for installation on a combustible wall and for installation in an alcove or closet with the minimum clearances to combustible and non combustible construction listed below A. Top 12 inches (306 mm) B. Front 4 inches (102 mm) C. Back 0 inches D. Sides 4 inches (102mm) E. Bottom 12 inches (306 mm) Clearance from vent is dependent upon the clearance rating of the venting material used. For example: type B-1 vent is approved for 1 inch clearance. Note: Typically, the minimum clearence to combustible materials should not be less than 6 for single wall flue pipe. Note that this clearance can be reduced if combustible materials are protected as per table VI of the National Fuel Gas Code or if Type B gas vent is used.
(10 X 10 in. each)
(5 X 5 in. each)
The 425HN is design certified for mounting on a wall. Secure the two L shaped hooks, which are provided with heater, to a wall surface. Place them 13 apart as shown in Fig. 2. Do not install this appliance on a carpeted wall or over floor covering which is combustible, such as carpet. The heater must be mounted on a wall using appropriate anchoring materials. If wall is a stud wall sheathed with plasterboard, it is recommended that support board(s), either 1x4s or 1/2" (minimum) plywood first be attached across a pair of studs and then the heater should be attached to the support boards. See Fig. 2. Expansion and contraction of piping due to changing water temperature in the pipes imparts movement to the heater which, if mounted directly to a brittle, friable board, such as
plasterboard, can cause failure of mounting. In earthquake-prone zones, CEC recommends that installers use a large washer and lag screw through the existing holes used to hang the heater to affix the upper third of the heater to the mounting board. To affix the lower third of the heater, CEC recommends that two new holes be drilled in the heaters frame, each one 16 inches below the top two holes, and that washers and lag screws be used to secure the lower portion of the heater to a spacing board. Before installing the unit, be certain you have the correct heater for your type of Gas Propane or Natural Gas. Identification labels are found on the shipping box, and on the rating plate which is located on the right side panel of the cover. Also, each burner orifice is stamped with a number (79 for LPG and 120 for Natural Gas).
appliance. The heater should never be common vented with a mechanically vented appliance. Single wall vent pipe is not recommended, if used consult the National Fuel Gas Code. Horizontally venting to a sidewall vent terminator or a vertically constructed vent stack along an outside wall of a building is not permissible. A Powervent (Model AQ-1), with a proof-of-draft safety interlock device, is required and is available in order to sidewall vent. Contact your dealer. In the Commonwealth of Massachusetts: Powervented applications must utilize proof-of-draft safety interlock device. A 5 inch diameter gas vent constructed of double wall Type B gas vent is recommended. 6 inch is required in elevations greater than 2000 feet, see Fig. 4. Any gas vent section that is greater than 45 degrees from the vertical is considered horizontal. Horizontal sections must slope upwards at least inch for every foot of its horizontal length and be properly supported. Keep the horizontal section short and avoid too many elbows. The minimum vertical gas vent height allowed is 6 feet; horizontal vent connectors and elbows are not to be considered in the total gas vent height. All gas vent sections must be secured to each other with sheet metal screws and be properly supported.
VERTICAL GAS VENT:
WALL STUDS 13 SUPPORT BOARD
1 X 4 SPACE BOARD
Fig. 2 - Mounting the Heater The incandescent particle tray (shipped loose in the carton with the water heater) must be attached at the bottom of the water heater front cover at the time of installation. Use the screws provided. See figure 3
The gas vent constructed of double wall Type B gas vent must terminate above the roof surface with a listed vent cap at a height thats in accordance with Figure A or B and their table, provided they are at least 8 feet (2.4 m) from a vertical wall or similar obstruction. All other gas vents that are not able to terminate within the minimum specified height allowed must terminate not less than 2 feet (0.6 m) above the highest point where its passed through the roof and at least 2 feet (0.6 m) higher than any vertical wall or similar obstruction within 10 feet (3.1 m).
Fig. 4 - Vent Adaptor for High Altitude Installations
NOTE: The 425 HN is supplied with a gas pressure regulator that must be installed on the heater before attaching the gas supply line. See fig. 5. Failure to install the gas regulator as shown in figure 5 will be a violation of CSA certification of the unit. The regulator supplied with the heater is preset for the gas shown on the rating plate to the correct pressure. It is an appliance level regulator designed for (low inlet) pressure (less than 1/ 2 Psig or 15 W.C.) DO NOT connect to an unregulated or high pressure propane line or to a high pressure commercial natural gas line.
GAS INLET PIPE
PLASTIC VENT CAP PRESSURE REGULATOR (with directional arrow on reverse side pointing upward)
Fig. 5 - Installation of Gas Pressure Regulator The pressure regulator provided with the heater is adjusted to deliver the proper gas pressure (as indicated on the rating plate and in the manual for altitude up to 2000 feet (660 meters) above sea level. On appliances being installed above 2000 ft (660 meters) elevation, the inlet gas pressure should be set at installation to the value shown below.
GAS PIPING, CONNECTIONS and Gas Regulator
Before connecting the gas supply, check the rating plate on the right side of the front cover to be sure that the heater is rated for the same gas to which it will be connected. In the United States: The installation must conform with local codes or, in the absence of local codes, the National Fuel Gas Code ANSI Z223.1/NFPA 54. In Canada: The Installation should conform with CGA B149 INSTALLATION CODES and /or local installation codes.
The gas supply piping should be sized according to the Applicable Plumbing Code for a maximum draw of 117,000 BTUH. First determine the effective length of the gas supply line by measuring the actual length of piping, and then adding 5 ft. for every elbow or T to the actual length. Use the charts below to determine the pipe diameter necessary to accommodate the BTU demand of the unit. If there are more gas drawing appliances on the line, size according to the maximum amount of BTU demand.
FOR NATURAL GAS
Maximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and a Pressure drop of 0.3 in Water Column. (Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands.
Nominal Iron Pipe Size, Internal Diameter 980 Length of Black Iron Pipe, Feet
Follow boxed numbers for piping just one 425 HN (example: 3/4 B.I. Natural Gas pipe for 30 ft. will handle 152,000 btus). For multiple appliances combine the total btu input load and then refer to applicable chart below.
Pipe to appropriate discharge Hot Cold
Fig. 7 - Pressure Relief Valve OPERATING INSTRUCTIONS Before proceeding with the operation of the heater make sure that the system is filled with water. Open the cold water inlet supply to the heater fully. Open a hot water faucet to permit the water to fill the heater and the piping and to eliminate the air trapped in the system Close the hot water faucet after the water flows freely and all the air has escaped from the system. The water heater is now ready to operate.
FOR YOUR SAFETY READ B EFORE OPERATING YOUR HOT WATER HEATER
Warning: If you do not follow these instructions exactly, a fire or explosion may result causing property damage, personal injury or loss of life. A. This appliance is equipped with electronic ignition for lighting the pilot and main burners. When turning the heater on, follow these instructions exactly. B. Before operating the unit, set the On/Off switch to the On ( ) position. The On/Off switch is located behind the flip-down coverplate on the front panel strip. Smell all around the appliance area for gas. Be sure to smell next to the floor because some gas is heavier than air and will settle on the floor. WHAT TO DO IF YOU SMELL GAS - Do not try to light any appliance. - Do not touch any electric switch; do not use any phone in your building - Immediately call your gas supplier from a neighbors phone. Follow the gas suppliers instructions. - If you cannot reach your gas supplier, call the fire department. C. Use only your hand to push in the on/off control button. Never use tools. Follow these instructions exactly. If control button is jammed, close the gas supply and call a qualified service technician. Attempted forceful repair may result in a fire or explosion. D. Do not use this appliance if any part has been under water. Immediately call a qualified service technician to inspect the appliance and to replace any part of the control system and any gas control which has been under water.
Fig. 6 - Water valve - top view
Connecting the pressure relief valve (PRV) A listed pressure relief valve supplied with the heater must be installed at the time of installation. No valve is to be placed between the PRV and the heater. No reducing coupling or other restriction may be installed in the discharge line. The discharge line must be installed such that it allows complete drainage of both the PRV and the line. The location of the PRV must be readily accessible for servicing or replacement, and be mounted as close to the water heater as possible. See Fig 7. To install the PRV, a suitable fitting connected to an extension on a T fitting can be sweated to the hot water line. Support all piping.
LIGHTING AND OPERATING INSTRUCTIONS
1. STOP! Read the safety information above on this label. 2. The gas valve must be shut off by putting the ON/OFF switch to position . Wait five (5) minutes to clear out any gas. If you smell gas, STOP! Follow B in the safety information above. If you do not smell gas, go to the next step. 3. This water heater is equipped with a safety pilot burner and an automatic ignition control system. 4. Set the ON/OFF switch (flip down cover plate on front panel strip) to the position. In this position, the water heater is ready to use. 5. If the red LED indicator light is flashing, this is a warning that the water pressure is not enough to ignite the main burner. 6. Turn the hot water faucet on to the minimum flow rate required to activate the heater. The automatic ignition system first ignites the safety pilot burner which then ignites the main burner in about 4 seconds. 7. The green LED indicator is on when the main burner is on. 8. The pilot flame will extinguish 10-30 seconds after the burners come on. The burners will remain on until the hot water tap is turned off. NOTE: On a first time initial installation, existence of air in the gas supply line and in the water line may cause some ignition delay. In that case, repeatedly open and close the hot water tap in order to restart the ignition process until all the air has been purged. TO TURN OFF GAS TO APPLIANCE Turn off the manual lever on the gas supply line to the heater and set the ON/OFF switch to the OFF ( ) position. See Fig 9.
The position you select on the temperature adjustment knob will depend on the temperature of the incoming water (50F is average in the U.S.). In warm weather regions where the incoming cold water is generally warmer, or during the hot weather months in some other areas a midway setting on the temperature adjustment knob would produce a temperature rise of about 70F, giving an output of approximately 120F. At this setting, if it is still necessary, one could mix a small amount of cold water in a shower and have a comfortable shower at about 3 gallons/minute. During the colder months, or in cold climate areas, it might be necessary to set the control to the maximum position, all the way clockwise to the right. If you supply the 425 HN, with preheated water (i.e.) in a solar installation the unit could overheat. It will then shut off on safety when the outlet temperature reaches 194F. For this type of application, purchase a solar model 125B LPS or 125B NGS. If the inlet water temperature to the water heater is very warm the heater can produce temperatures that may be found to be too hot. A temperature balance shower valve can automatically mix in cold water to reduce such hot water temperature, in the event of any temperature instability with the use of a temperature balance shower valve, refer to shower valve manufactures instructions for internal adjustment setting. Adjustments should be made to the hottest setting in the shower valve. Additionally the temperature control of the heater can be adjusted to produce a more comfortable hot water temperature.
To start and to shut down the appliance press the button . The switch is located behind the flip down cover plate on the front panel strip.
SETTING THE WATER TEMPERATURE
The 425 HN LP and 425 HN NG water heaters have a gas control that modulates burner input in response to flow. Its purpose is to ensure that the hot water temperature will remain steady, although the water flow demand might vary (down to 1/2 gal/minute). To adjust the temperature on your 425 HN, turn on a hot water faucet to its maximum flow. At the water heater, turn the large knob located beneath the main gas control on the front of the heater all the way to the right (clockwise). See Fig 8. This will produce a temperature rise of approximately 90F at flow rates between 0.5 and 2.0 gallons per minute. Given that average incoming water temperatures are 50F, this heater will produce approximately 140F water at these flow rates. Turning the dial all the way to the left (counterclockwise) will produce a temperature rise of approximately 45F for flow rates between 1.1 and 3.7 gallons per minute. It is safest to select a comfortable temperature and not have to mix in cold water.
- on - off
Green light on = main burner on. Green light off = main burner off.
If the red light is flashing, that means the water flow is not enough to ignite the burner.
Temperature Adjustment Knob Decrease temperature Increases temperature and increase flow and decreases flow
Fig. 8 - Temperature Adjustment Knob
Fig. 9 - Principles of Operation
MAINTENANCE AND SERVICE
REVIEW MAINTENANCE TABLE ON THE BACK OF THIS MANUAL. Approximately once a year, the 425 HN should be checked and cleaned. To remove the front cover, first remove the incandescent particle tray, then pull off the temperature adjustment knob and unscrew and remove the plastic collar. Pull main cover out toward you and lift up and out. THE FOLLOWING OPERATIONS SHOULD BE PERFORMED BY A QUALIFIED SERVICE PERSON: Vent System: Should be checked annually. Clean and repair as needed. Water Valve (Part # 8707002649): The water valve on this heater should be serviced periodically. Lubricate component 36 on page 18 with a small amount of silicon, faucet or lithium grease every two years to keep its o rings fresh and pushrod sliding smoothly. Every 3-5 years replace component 36 on page 18. The frequency will depend on the mineral content of the water and conditions of use or whenever signs of corrosion appear at the gas and water valve joint. Periodically check that the water inlet filter (#27 on page 18) is clean as well. NOTE: If water valve is removed, be sure to also inspect the o ring seal on the end of the right hand side water pipe before re-installing. Lubricating the o ring with lithium or faucet and valve grease is recommended.
To clean the pilot burner and/ or the pilot orifice : Turn off the gas to the unit. Set the On/Off switch to Off (position ). Remove the cover of the heater. To do so, pull off the temperature adjustment knob and unscrew and remove the plastic collar. Pull main cover out toward you and lift up and out. The pilot orifice should be cleaned or replaced. Do not enlarge the orifice. Do not use any wire or sharp object to clean orifices. Natural gas orifices are large enough that you can usually clean them by blowing through them. LP orifices, on the other hand, are too small to clean and should be replaced. To access the pilot orifice, remove 2 screws holding pilot assembly in place. Then loosen compression fittings to expose pilot orifice.
Pilot Flame: The pilot flame should burn with a clean, sharp, blue flame and should resemble the diagram in Fig. 10. If the flame is soft and yellow, the pilot burner orifice may need to be cleaned or replaced. The pilot flame should be approximately 2 inches long, extending past the flame sensor. If the flame is too small, it will not reach the flame sensor and the burners will not come on.
3mm Correct gap between pilot burner tip and electrode tip
Fig. 11 - Pilot burner with pilot orifice (Pilot assembly shown without pilot hood) Main Burner Flames: The main burner flames should be blue, with a more intense blue cone in the center core. Yellow flames could be a sign of wrong size gas orifices or dirty burners, or a blockage on the heat exchangers fins. If some burners have yellow flames while others have good flames, it is likely that dust, lint or spider webs have partially clogged the burner venturis. To clean the burners, contact a gas service person. Mineral Scale Build-up: The 425 HN heater, when operated at lower temperature settings, does not accumulate mineral build-up. If however, the heater is used at the higher temperature settings and the water has a high mineral content, periodic descaling may be necessary. The heating coils should be flushed with a descaling solution. The descaling is done only to the heat exchanger. The chemicals will damage the hydro-generator and other parts. Consult your service person.
Introduction The 425 HN burners are activated by a water flow valve. Numerous water related problems can cause this water valve to malfunction such as: Insufficient water flow volume to activate the burners at its minimum flow requirement; Dirt in the water flow valve causing it to malfunction; Sediment build-up in faucet aerators, or shower heads; Uneven pressures between cold and hot. (with single lever faucets) Plumbing cross overs. These water flow related problems can cause the heater to deliver less than its full output, or to fail to ignite or to shut down completely.
Fig. 10 - Characteristic Pilot Flame (Pilot assembly shown without pilot hood)
Problems are stated in upper case, bold face. Most common causes for the problems follow in order of likelihood. The suggested solutions require that the cover be taken off. To do this, remove incandescent particle tray, pull off the temperature adjustment knob and unscrew and remove the plastic collar. Pull main cover out toward you and lift up and out.
SPARK APPEARS AT PILOT WHEN HOT WATER TAP TURNED ON, BUT PILOT AND BURNERS WILL NOT IGNITE 1. Air in the Gas Line Normally this is a problem at time of initial installation, after the pipes have been worked on, or after a gas supply line has been allowed to empty. Bleed the air trapped in the gas line by turning the hot water faucet on and off until the air has been cleared from the line. 2. No gas to the 425 HN A. Gas cock on gas line may not be open B. Gas regulator may be shut or damaged. Replace or unlock the regulator. Note: The regulator furnished with the heater is exclusively designed for low gas pressure. Excessive pressure will lock it up. Locking usually happens when using propane gas if the gas pressure between the gas tank and the water heaters gas regulator has not been reduced. See Page 2 for recommended correct gas pressure. To unlock a regulator, consult your service person. 3. Pilot orifice or gas valve is dirty Clogging of the pilot burner can be caused by dust in the air or dirt in the gas. The pilot orifice or gas filter may need to be cleaned or replaced. 4. Pilot electrovalve switch may need to be replaced (See Fig 13). Measure milivoltage at pilot electrovalve (see Fig. 13). 5. Electronic Control Box may need to be replaced (See Fig 13). Check wire connections and test operation of electronic control box (see Fig. 13).
5. Flue gas safety device tripped Ventilate the room and operate the appliance 10 minutes later. Provide more combustion air to the room and/or inspect and correct venting system. Afterwards, if it happens again, contact your service person. WATER IS TOO HOT 1. Temperature Selection too high Turn the temperature adjustment knob counter-clockwise (to the left) to lower the maximum water temperature. Note: This will increase the activation flow rate. 2. Inlet water temperature is too hot (as with solar preheated water or high ground water temperatures) Decrease gas pressure. Note: Only the model 125B LPS or 125B NGS should be used if the inlet water is preheated. 3. Ground water temperature is very warm Reduce inlet gas supply to heater when inlet water temperature is very warm (60-70 F). See also HOT WATER TEMPERATURE FLUCTUATES / UNIT DEACTIVATED. WATER IS NOT HOT ENOUGH 1. Temperature selection too low. Change the setting. Turn the temperature adjustment knob clockwise (to the right). Note: This will decrease the activation flow rate. 2. Btu input is too low due to insufficient gas pressure It is extremely important for a tankless instantaneous water heater to have the right size gas line to obtain the correct gas pressure See specifications on page 2. Unlike storage tank water heaters, the burners of a tankless water heater must be very powerful to heat water instantaneously since they do this only at the time hot water is actually being used. It is therefore imperative that the gas pressure requirement be met exactly. Insufficient gas pressure will directly affect the water temperature at the time of usage. See page 2 for correct gas pressure settings and fig. 5 for locations where gas pressures are taken. 3. Btu input is too low due to insufficient gas supply Make sure your main gas line is fully opened. If using LP gas, be sure that the size of the propane tank is adequate to supply the required gas pressure. 4. Cold water is mixing with the hot water between the 425 HN and the outlet Compare water temperature at outlet of the 425 HN (hold the 425 HN outlet pipe with your hand) and at the tap. If these two are very different, check for mixing valve or plumbing crossover (see NO SPARK AT THE PILOT paragraph #4). 5. Parts in water valve are dirty or damaged, which will prevent the gas valve from being fully opened. Water valve maintenance needs to be performed, see #6 under NO SPARK AT THE PILOT
Fig. 14 - Diagram of 425 HN
1. Heat exchanger 2. Pilot assembly 3. Burner manifold gas pressure test nipple 4. Main gas burner 5. Pilot gas tubing 6. LED failure indicator
7. 8. 9. 10. 11. 12.
on/off switch LED operation indicator Water valve Temperature adjustment selector Gas inlet gas pressure test nipple Hose
Fig. 15 - INTERIOR COMPONENTS DIAGRAM AND PARTS LIST
INTERIOR COMPONENTS DIAGRAM AND PARTS LIST 425 HN
45 Cover Temperature adjustment knob Temperature adjustment collar Draft diverter Heat exchanger Main burner Main burner Burner assembly washer Throttle disc Pilot burner Pilot burner Pilot electrode Pilot orifice Pilot orifice Pilot tube Washer pilot tube Gas valve Gas valve Diaphragm switch Diaphragm switch Pilot electrovalve Burner electrovalve O-ring Hydro-generator Cold water pipe Outlet flex hose Washer Water valve Water valve cover Diaphragm Water inlet filter Water valve selector screw Volumetric water governor Venturi Electronic control box Flame sensor cable Electrode cable Flue Gas Sensor Set of cables Pushrod O-ring O-ring Water connection gasket Water elbow fitting Overheat sensor (ECO) Connecting pipe hot Washer Flame sensor Water valve set screw 401 051
NG LP LP LP NG NG LP
NG LP NG LP
Fig. 16 - Flow chart of 425 HN
Fifteen Year Limited Warranty
General B OSC H PRO water heaters are warranted by the Manufacturer (BOSCH) through Controlled Energy Corp. Controlled Energy Corp. (CEC) 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 CEC 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. The Heat Exchanger If the heat exchanger fails within fifteen (15) years after the original installation and operation, CEC will furnish a replacement heat exchanger. However, if the water heater is installed in other than a single family dwelling this heat exchanger warranty is limited to two (2) years from date of original installation and operation. Exceptions This warranty will not apply: 1. to defects or malfunctions resulting from failure to properly install, operate or maintain the unit in accordance with the printed instructions provided; 2. to damage or abuse, accident, neglect or freezing and other acts of nature; 3. to damage resulting from operation with either the flame sensor rod or overheat sensor removed; 4. to failure of the heat exchanger resulting from the operation of the water heater in a corrosive atmosphere or at water temperatures exceeding the maximum rating, or if the water heater is not supplied with potable water; 5. to defects or damage cause by any attachment or modification, including any energy-saving device. All Other Parts If any other part fails within three (3) years after original installation and operation, CEC will furnish a replacement part free of charge. Shipping costs In addition to supplying the replacement part(s), CEC will provide ground service delivery for these parts. Expedited or upgraded shipping will be charged to the customer. Service Labor Costs This warranty does not cover any labor costs associated with service, removal or re-installation of part(s). All such costs must be borne by the Purchaser. Additionally, this warranty does not cover any labor costs associated with service, removal or re-installation of the original water heater or a replaced water heater. Certain service labor allowances are available to PHCC member contractors, dependent on prior authorization by CEC. NOTE: the water heater must be free of damaging scale deposits and not subject to gas pressures greater than those shown on the rating plate, which must not be altered, defaced or removed. How to Make a Claim Any claim for warranty parts should be made to your local dealer, distributor or to CEC. If CEC, please contact the Technical Support Department: Controlled Energy Corp. 340 Mad River Park Waitsfield, VT 05673 Phone: 866-330-2730 www.protankless.com In most cases, the dealer or distributor will be able to promptly honor your claim and subsequently notify CEC. However, all replacements are made subject to validation by CEC of in-warranty coverage. The damaged or defective item must be made available in exchange for the replacement. Miscellaneous No one is authorized to make any other warranties on behalf of CEC. It is expressly understood that the replacement warranty of CEC shall be in lieu of any and all other warranties, express or implied, including warranties of merchantability or fitness for a particular use or purpose, and further that CEC shall not be liable for any loss or damage directly or indirectly arising from the use of the hot water heater, or for any consequential damages arising from such use (including damages from water leakage). CECs sole liability with respect to any defect shall be for the replacement of the defective part(s). Some states do not allow such limitations and exclusions, so the above may not apply to you. This warranty gives specific legal rights. You may also have other rights which vary from state to state.
MAIN TEN AN C E TAB LE see page 13
LU B R IC ATE WATER VALVE R EB U ILD WATER VALVE IN SPEC T WATER FILTER SC R EEN IN SPEC T PILOT ASSEMB LY IN SPEC T VEN T ASSEMB LY IN SPEC T MAIN B U R N ER
EVERY 2 YEAR S
EVERY 3-5 YEAR S
Replacement Parts available from North American Distributor
CONTROLLED ENERGY CORP.
340 Mad River Park Waitsfield, Vermont 05673 Phone 866-330-2730 Fax (802) 496-6924 www.protankless.com firstname.lastname@example.org VULCANO Termodomsticos S.A. Estrada de Cacia 3801 - 856 Aveiro - PORTUGAL
2004 Controlled Energy Corporation, Waitsfield, VT all rights reserved
Bosch GWH-425-HN-N Tankless Water Heater, Indoor Use Ideal for households looking to maximize energy savings. New homeowners want the energy-efficient, endless supply of hot water only a gas tankless water heater can deliver. Elegantly engineered, these units are small, lightweight, and easy to install and maintain. Patented Bosch Hydro-Generated Ignition Technology. The Bosch engineers have proven that water can indeed make fire. The pilot is ignited by a super-concentrated spark generated by a micro-turbine. The micro-turbine is activated by a request for hot water in the house. This energy efficient technology makes the 425 HN ideal for households looking to maximize energy savings. - 80% a
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