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Bosch Pro Tankless GWH-450-ES Series Manual

Temperature modulated with electronic ignition - normal duty suitable for recirculating potable water only
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GWH 450 ES
Temperature Modulated with Electronic Ignition - Normal duty
Suitable for recirculating potable water only
GWH-450-ES-N - Natural Gas
GWH-450-ES-L - Liquefied Petroleum (LP) Gas
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,
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.
adjustment,
alteration,
What to do if you smell gas
• Close gas valve. Open windows.
• Do not try to operate any appliance.
• Do not touch any electrical switch; do not use any
phone in your building
• Immediately call your gas supplier from a neighbor's
phone. Follow the gas supplier's instructions.
• If you cannot reach your gas supplier, call the fire
department.
• Installation and service must be performed by a qual-
ified installer, service agency or the gas supplier.

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  Summary of Contents for Bosch Pro Tankless GWH-450-ES Series

  • Page 1 GWH 450 ES Temperature Modulated with Electronic Ignition - Normal duty Suitable for recirculating potable water only GWH-450-ES-N - Natural Gas GWH-450-ES-L - Liquefied Petroleum (LP) Gas Warning: If the information in this manual is not What to do if you smell gas followed exactly, a fire or explosion may result •...
  • Page 2: Table Of Contents

    Index Index Warning Warning For your safety Appliance details Do not store or use gasoline or other flammable, Features combustible or corrosive vapors and liquids in the GWH-450-ES Specifications (Technical data) vicinity of this or any other appliance. Unpacking the GWH-450-ES heater General rules to follow for safe operation Warning: Carefully plan where you Cascading function...
  • Page 3 Warning Warning: The recirculating water heater must be disconnected from the gas supply piping system during any pressure testing of that system at test pressures equal to or more than 0.5 psig. FCC: This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received,...
  • Page 4: Appliance Details

    Natural Gas. Liquid Propane. Approved in US/Canada Converting the gas type can only be done by a certified gas technician. Call Bosch Water Heating for Capacity conversion information. GWH450 Maximum flow rate: 4.5 GPM (17 l/min) at a 45°F (25°C) rise.
  • Page 5: Unpacking The Gwh-450-Es Heater

    Appliance details Water resistant To remove front cover IP X4 (protection against water drops) The front cover is secured with two screws to prevent unauthorized access. Unpacking the GWH-450-ES heater Always secure the control panel and front cover with these screws. This water heater is packed securely.
  • Page 6: General Rules To Follow For Safe Operation

    Appliance details General rules to follow for safe Cascading function operation GWH-450-ES always work as master. Cascading enables the appliance to be connected in B 1. You should follow these instructions when you parallel with up to 4 World 1 appliances. World 1 will install your water heater.
  • Page 7: Dimensions And Minimum Installation Clearances

    Appliance details Dimensions and minimum installation clearances Fig. 4 Dimensions Combustion air inlet adapter (right side only) Exhaust adapter with CO measuring point Front cover On/Off button Reset button ECO flow thermostat LED - (ON) warning light (blinks when in lock out) Hot water thermostat Mounting plate Fig.
  • Page 8: Applications

    Introduction The application designs provided in this manual are general guides to be used when installing this recirculating water heater. Additional application designs are available from Bosch Water Heating. Instantaneous water heater (direct tank load version) Fig. 6...
  • Page 9: Installation Instructions

    Installation instructions Installation instructions Introduction Water heater placement and clearances Please follow these instructions. Failure to follow instructions may result in: The GWH-450-ES is design certified for installation on a combustible wall (see 3.4 Mounting installation) • Damage or injury provided the floor covering below the water heater is •...
  • Page 10: Combustion Air Requirements

    Installation instructions top right side of the combustion air inlet to prevent foreign object from falling into the unit (see Fig. 17). If a single pipe installation is performed. Use the following guidelines when providing adequate combustion air for the recirculating water heater as well as any other appliances that may consume air in the space.
  • Page 11: Venting

    Carbon Monoxide poisoning could result. Bosch Water Heating will not be responsible for improperly installed appliances. Establish vent clearances that comply with the vent manufacturer's specifications. In all cases follow local codes. See Table 3.
  • Page 12 Installation instructions Fig. 13 Exhaust Fig. 10 Side vent Fig. 14 Air inlet B Attach the flue gas exhaust accessory (8 705 504 Fig. 11 Rear vent 142) to the top of the unit (position 1) using the 4 Vent Safety System screws and gasket provided, and fully insert 3"...
  • Page 13 Installation instructions Restrictor definition Use table below to define which restrictor to be used. Total equivalent Restrictor length (ft) Ø 18 -28 28 -40 40 -65 65 -100 18 -28 28 -50 50 -75 75 -100 Table 4 Restrictors Selecting a restrictor (sample) Described example was done taking as example Fig.
  • Page 14: Venting Options

    Installing this water heater as a room sealed (TWIN PIPE SYSTEM) is the recommended method. Contact Not recommended in cold climate areas, see Bosch Water Heating or dealer for available vent Chapter 3.5. termination kits and vent materials for this water heater.
  • Page 15 Installation instructions Recommended exhaust vent terminator position Fig. 18 Ref. Description Minimum distance Directly below an opening; operable windows, doors and any non- 12 in (twin pipe installation) mechanical fresh air openings 48 in (single pipe installation) Below a gutter, sanitary pipework or eaves 24 in Below a gutter, sanitary pipework or eaves, protected by metal 12 in...
  • Page 16: Gas Piping & Connections

    Installation instructions B National Fuel Gas Code requires that a sediment Supporting the exhaust vent system trap (drip leg) be installed on gas appliances not so equipped. The drip leg must be accessible and not subject to freezing conditions. Install in accordance with the recommendations of the serving gas supplier.
  • Page 17 Installation instructions 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 (0.75mbar).(Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands. Follow boxed numbers for piping just one GWH-345/450-ESR (example: ¾”...
  • Page 18: Measuring Gas Pressure

    Installation instructions B After 10 seconds, press and hold the reset button National Fuel Gas Code requires that a sediment trap (drip leg) be installed on gas appliances not so equipped. Also, a manual gas shut off valve must be B Rotate the recirculating water temperature selector installed on the gas supply line within close proximity of (left knob) to the minimum and then to maximum.
  • Page 19: Water Connections

    Installation instructions Water connections reducing coupling or other restriction may be installed in the discharge line. The discharge line must be a B When facing the water heater, the ¾” return is on the minimum of 4” above a drain and installed such that it bottom right and the supply is on the bottom left.
  • Page 20: Operating Instructions

    Operating instructions Operating instructions B Use only your hand to press the on/off control switch. Before proceeding with the operation of the water heater make sure that the system is filled with water: Never use tools. Follow these instructions exactly. If control switch is jammed, close the gas supply and B Turn off power supply to water heater.
  • Page 21: Power

    Operating instructions Power Power adjustment Note: only when using the 12 kOhm DHW thermistor. To start the appliance: B Connect thermistor to blue wire with terminal block. B press the ON/OFF button. Power can be set from 70% to 100% of full power in LED (fig.
  • Page 22: Electrical Diagram

    Operating instructions Electrical diagram Fig. 29 Electrical scheme Control electrode Spark plug Gas valve Temperature limiter Differential pressure switch Primary circuit temperature sensor Flow switch 6 720 607 915...
  • Page 23: Maintenance And Service

    Maintenance and service Maintenance and service Warning: Always turn off the electrical power supply, turn off the manual gas valve and turn off the manual water control valves whenever servicing. The unit should be checked once a year by a gas technician.
  • Page 24: Troubleshooting

    Troubleshooting Troubleshooting Fault Indication Possible Cause Check Orange LED + 100°F flashing Shut down by the temperature limiter • Check position of heating NTC (over temperature). • Check temperature limiter, cables • Check system with air, air vent Orange LED + 110°F flashing No Flame detected (no ignition).
  • Page 25 Troubleshooting Malfunction Cause Solution Orange LED + 100°F - The appli- Over heating detected • Check if there is any obstruction on temperature limit stat. central heating circuit ance shuts down shortly after the • Purge the central heating installation ignition.
  • Page 26: Gwh-450-Es Functional Scheme

    GWH-450-ES Functional scheme GWH-450-ES Functional scheme Fig. 30 Functional scheme 6 720 607 915...
  • Page 27: Interior Components Diagram And Parts List

    Interior components diagram and parts list Interior components diagram and parts list Interior components Fig. 31 Components Combustion air inlet adapter (right side only) Exhaust adapter with CO measuring point Front cover On/Off button Reset button ECO flow selector LED - (ON) warning light (blinks when appliance in lock out) Hot water temperature selector LED to display error codes and temperatures Gas valve...
  • Page 28: Components Diagram

    Interior components diagram and parts list Components diagram Fig. 32 Components Diagram 6 720 607 915...
  • Page 29: Parts List

    Interior components diagram and parts list Parts list Item Description Reference Item Description Reference Screw(10x) 8 703 401 069 0 GROUP 1 Screw M4 x 12 phillips (10x) 2 910 952 122 0 Front cover 8 705 431 223 0 Nozzle (125) (10x) 8 708 202 116 0 Screw no.
  • Page 30: Protecting The Environment

    Protecting the environment Protecting the environment Packing The packing box may be fully recycled as confirmed by the recycling symbol Components Many parts in the heater can be fully recycled in the end of the product life. Contact your city authorities for information about the disposal of recyclable products.
  • Page 31: Fifteen Year Limited Warranty

    How to Make a Claim The Heat Exchanger Any claim for warranty parts should be made to your local dealer, distributor or to Bosch Water Heating. If If the heat exchanger fails within fifteen (15) years after Bosch Water Heating, please contact the Technical...
  • Page 32 Installer Checklist, to be performed by installer upon installation Serial Number ___ ___ ___ ___ ___ ___ ___ ___ (8 digit serial number is located on rating plate on right side panel) Gas Pressure Reading* Static__________ Operating__________ Building Water Pressure __________ Range if on Well system __________ Installing Company _____________________________________________...

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Pro tankless gwh-450-es-nPro tankless gwh-450-es-l