GWH-450-ES
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, 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.
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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 qualified installer, service agency or the gas supplier.
Index
Index
1 Warning 2
2 Appliance details 4
2.1 Features 4
2.2 GWH-450-ES Specifications (Technical data) 4
2.3 Unpacking the GWH-450-ES heater 5
2.4 General rules to follow for safe operation 6
2.5 Cascading function 6
2.6 Dimensions and minimum installation clearances 7
2.7 Applications 8
3 Installation instructions 9
3.1 Introduction 9
3.2 Proper location for installing your water heater 9
3.3 Water heater placement and clearances 9
3.4 Mounting installation 9
3.5 Combustion air requirements 10
3.6 Venting 11
3.6.1 Venting options 14
3.7 Gas piping & connections 16
3.8 Measuring gas pressure 18
3.9 Water connections 19
3.10 Electrical connections 19
4 Operating instructions 20
4.1 For your safety read before operating your water
heater 20
4.2 Startup instructions 20
4.3 Power 21
4.4 Water temperature 21
4.5 Power adjustment 21
4.6 Freeze prevention 21
4.7 Electrical diagram 22
5 Maintenance and service 23
6 Troubleshooting 24
7 GWH-450-ES Functional scheme 26
8 Interior components diagram and parts list 27
8.1 Interior components 27
8.2 Components diagram 28
8.3 Parts list 29
9 Protecting the environment 30
10 Fifteen Year Limited Warranty 31
1 Warning
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.
Warning: Carefully plan where you
install the heater. Correct combustion
air supply and flue pipe installation are
very important. If a gas appliance is not
installed correctly, fatal accidents can
result from lack of air, carbon monoxide
poisoning or fire.
Warning: Exhaust gas must be vented
to outside using proper vent material
suitable for category III vent systems
and temperatures up to 480°F. Vent
and combustion air connector piping
must be sealed gas-tight to prevent
possibility of flue gas spillage, carbon
monoxide emissions and risk of fire,
resulting in severe personal injury or
death.
Warning: Place the recirculating water
heater in a location where water leaks
will do NO DAMAGE to adjacent areas
or lower floors.
Warning: Field wiring connections and
electrical grounding must comply with
local codes, or in the absence of local
codes, with the latest edition of the
National Electric Code, ANSI/NFPA 70,
or in Canada, all electrical wiring must
comply with the local codes and the
Canadian Electrical Code, CSA C22.1
Part 1.
Warning: Shock hazard line voltage is
present. Before servicing the
recirculating water heater, turn off the
electrical power to the recirculating
water heater at the main disconnect or
circuit breaker. Failure to do so could
result in severe personal injury or death.
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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,
including interference that may cause undesired
operation.
Caution: Any changes or
modifications not expressly approved
by the party responsible for compliance
could void the user’s authority to
operate the equipment.
Warning
Fig. 1
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3
Appliance details
2 Appliance details
2.1 Features
Parts
• Sealed combustion burner.
Safety
• Ionization flame sensor
• Over temperature protection.
High quality materials for long working life
• Copper heat exchanger
• Compact space saver: mounts on a wall with
supplied bracket.
Features
• LED to display temperatures, burner operation and
diagnostic error codes.
• On/Off button and separate temperature controls for
domestic and heating
• Reset button
• Failure code for diagnostics and repair
• Freeze prevention cycle.
Accessories
• Horizontal vent kit
• Pump manifold
• 12 kOhm DHW thermistor.
BOSCH is constantly improving its
products, therefore specifications are
i
subject to change without prior notice.
Gas Requirement
Gas connection (inches) - ¾”
Inlet gas pressure under operation (with a high hot
water flow rate)*
• Propane: 11” - 14” water column
• Natural Gas: 5.5” - 8” water column.
* To measure Gas Pressure, see Measuring Gas
Pressure, chapter 3.8.
Venting
3" AL 29-4C Stainless Steel exhaust.
See chapter 3.6 for Venting.
Water
• Hot water connection (inches) - ¾”
• Cold water connection (inches) - ¾”
• Connections:
– Bottom of heater
Combustion
•NOx ≤ 55 ppm
•CO ≤ 250 ppm
•CO
Dimensions
• Depth (in): 11 ¾” (300 mm)
• Width (in): 15 ¾” (400 mm)
• Height (in): 27 ½” (700 mm)
• Weight: 47 pounds (21 kg).
level (see table 4 for correct restrictor
2
dimension).
2.2 GWH-450-ES Specifications
(Technical data)
Approved in US/Canada
Capacity
GWH450 Maximum flow rate: 4.5 GPM (17 l/min) at a
45°F (25°C) rise.
Maximum output
GWH450 - 98,400 Btu/h (28.8 kW)
Maximum input
GWH450 - 120,000 Btu/h (35.1 kW)
Efficiency in %
Recovery efficiency 82%
Min. Output
GWH450 - 34,200 Btu/h (10 kW)
Temperature Control
Selection range: 100°F (40°C) - 140°F (60°C)
4
Gas types
Natural Gas.
Liquid Propane.
Converting the gas type can only be done by a certified
gas technician. Call Bosch Water Heating for
conversion information.
Voltage
120 V AC (50/60 Hz)
Amperage
IDLE - 40 mA
Operation - ≤ 1,5 A
Noise
≤ 50 db (A)
Safety devices
• Flame failure device (Ionisation flame control)
• Over heat prevention (temperature limiter)
• Pressure switch (exaust protective faulty).
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Appliance details
Water resistant
IP X4 (protection against water drops)
2.3 Unpacking the GWH-450-ES heater
This water heater is packed securely.
The box includes:
• Wall-mounted gas water heater
• Bracket and screws for wall hanging the water heater
• Exhaust vent adaptor (with 4 screws and gasket
provided)
• Combustion air inlet adaptor (with 4 screws and
gasket provided)
• Installation manual
• Product registration card
• Energy Guide label
• Safety water pressure valve
• Air deflector
•Restrictors.
Do not lose this manual. Please complete and return
the enclosed product registration card.
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.
To remove front cover
The front cover is secured with two
screws to prevent unauthorized access.
i
Always secure the control panel and front
cover with these screws.
B Loosen the two Philips head screws located as
shown in fig. 2.
Fig. 2 Screws
B Pull control panel outwards and then pull it
downwards.
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Fig. 3 Service position to access water and electric
systems.
B Lift front cover panel upward and remove.
The GWH-450-ES is not approved or designed
for:
• Manufactured (mobile) homes, RV's or boats
•Outdoor installation
• Combination venting with other appliances.
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Appliance details
2.4 General rules to follow for safe
operation
B 1. You should follow these instructions when you
install your water heater. 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.(1,2) INSTALLATION CODES and /or
local installation codes.
B 2. Carefully plan where you install the water heater.
Correct combustion air supply and vent pipe
installation are very important. If not installed
correctly, fatal accidents can be caused by lack of air,
carbon monoxide poisoning or fire.
B 3. The National Fire Codes do not allow
UNSEALED gas fired water heater installations
in bathrooms, bedrooms or any occupied
rooms normally kept closed. See chapter 3.2
and 3.5.
B 4. You must vent your water heater. See section on
VENTING.
B 5. The appliance and its gas connection must be leak
tested before placing the appliance in operation.
The appliance must be isolated from the gas supply
piping system by closing its individual manual gas
shutoff valve (not supplied with water heater) during
any pressure testing at pressures in excess of ½ Psig
(3.5 kPa).
B 6. Keep water heater area clear and free from
combustibles and flammable liquids. Do not locate
the heater over any material which might burn.
B 7. Correct gas pressure is critical for the optimum
operation of this water heater. Gas piping must be
sized to provide the required pressure at the
maximum output of the water heater, while all the
other gas appliances are in operation. Check with
your local gas supplier, and see the section on
connecting the gas supply.
B 8. Should overheating occur or the gas supply fail to
shut off, turn off the gas supply at the manual gas
shut off valve, on the gas line. Note: manual gas
shutoff valve is not supplied with the water heater.
B 9. Do not use this appliance if any part has been
underwater. 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 underwater.
2.5 Cascading function
GWH-450-ES always work as master.
Cascading enables the appliance to be connected in
parallel with up to 4 World 1 appliances. World 1 will
only start, if it gets a signal from the GWH-450-ES and
will (at a defined power output level) give this signal to
the next appliance. That means, the appliance works
always as a Master to the next appliance and always as
a Slave to the one before.
For more detailed information about this feature, consult
the instructions supplied with the accessorie:
• 7 709 003 617.
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2.6 Dimensions and minimum installation clearances
Appliance details
Fig. 4 Dimensions
1 Combustion air inlet adapter (right side only)
2 Exhaust adapter with CO
3 Front cover
4 On/Off button
5 Reset button
6 ECO flow thermostat
7 LED - (ON) warning light (blinks when in lock out)
8 Hot water thermostat
9 Mounting plate
measuring point
2
Fig. 5 Minimum clearances
Model GWH-450-ES
TOP 12”
FRONT (B) 4”
BACK 0”
SIDES ½”
BOTTOM 12”
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VENT DIAMETER 3”
Table 1 Minimum clearances
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Appliance details
2.7 Applications
Caution: the water heater which will be
used to supply potable water shall not
be connected to any heating system or
component(s) previously used with a
nonpotable water heating appliance.
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
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3 Installation instructions
Installation instructions
3.1 Introduction
Please follow these instructions. Failure to follow
instructions may result in:
•Damage or injury
• Improper operation
• Loss of warranty.
Please contact BBT North America with any questions.
3.2 Proper location for installing your
water heater
Carefully select the location of the water heater. For
your safety and for proper operation, you must provide
combustion air to the water heater and a proper exhaust
vent system.
Follow the guidelines below:
B 1. Locate the water heater where venting, gas and
plumbing connections are feasible and convenient.
B 2. The hot water lines should be kept short to save
energy. Centrally locating the water heater is best. It
is always best to have hot water lines insulated.
3.3 Water heater placement and
clearances
The GWH-450-ES is design certified for installation on
a combustible wall (see 3.4 Mounting installation)
provided the floor covering below the water heater is
noncombustible. For installations in an alcove or closet,
maintain the minimum clearances to combustible and
non-combustible materials listed below. See also fig. 5.
A. Top 12 inches (305 mm)
B. Front 4 inches (100 mm)
C. Back 0 inches
D. Sides ½ inches (12 mm)
E. Bottom 12 inches (305 mm)
Clearances from any exhaust vent pipe are dependent
upon the clearance requirements of the stainless steel
vent pipe manufacturer. Single wall stainless steel
(AL29-4C) vent pipe (vent type rated for Category III
appliances) must be used when exhaust venting this
appliance. See 3.6 Venting.
3.4 Mounting installation
Warning: The water in this water
heater is cold and always remains cold
except for the times the burners are on.
In the event of power outage in
conjunction with freezing temperatures,
it is recommended that the heater be
drained. See chapter 5 for draining
instructions.
Warning: Flammable materials,
gasoline, pressurized containers, or any
other items or articles that are potential
fire hazards must NOT be placed on or
adjacent to the water heater. The
appliance area must be kept free of all
combustible materials, gasoline and
other flammable vapors and liquids.
Warning: before starting installation:
B check that there are no loose parts
inside the appliance
B check the gas type of the water heater
matches the gas supply you will be
connecting to the heater.
B ensure that gas pipe, gas valve, fan and
burner have no damage and are properly fitted.
Front cover should be removed (see
instructions on page 5) in order to inspect
i
components visually.
B Secure the wall mounting bracket provided with the
water heater to a wall surface.
Warning: Do not install this appliance
on a carpeted wall. The water 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 1x4.s or 1/
2" (minimum) plywood first be attached across a pair of
studs. Then attach the heater’s bracket to the upper
support board. The water heater should be kept level on
the wall surface. See Fig. 7.
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Installation instructions
Fig. 7 Mounting the water heater
3.5 Combustion air requirements
Warning: In areas where freezing
temperatures are common the twin pipe
system is recommended. A negative air
condition may result in cold air being
drawn across the heat exchanger coil
causing it to freeze and burst. This
failure is not covered under the
manufactures warranty.
Warning: When installed in an
environment where corrosive chemicals
or dirty air are present the twin pipe
system is required.
Twin pipe
The GWH-450-ES is designed as a sealed combustion
appliance. It is recommended that the combustion air
be provided by a dedicated 3” pipe to the outside. The
combustion air pipe may be constructed of aluminum
flex, PVC or any other rigid or semi rigid sealed 18 inch.
The combustion air inlet should be located in such a
manner as to provide a 3 foot clearance from the
exhaust vent terminator. See Fig. 18 Letter I.
The maximum length of the combustion air inlet is 39
feet with one elbow. Subtract 6 feet for additional
elbows. Maximum number of elbows permitted is 4.
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. Always follow local codes if more stringent.
• Appliances located in unconfined spaces:
– a) An unconfined space is one whose volume is
greater than 50 cubic feet (1.42 cubic meter) per
1000 Btu per hour (292.81 Watts) of the
combined rating of all appliances installed in the
space. That would be 6200 cubic feet (175.6
cubic meter) for the GWH-450-ES alone.
– b) In unconfined spaces in buildings of
conventional frame, masonry, or metal
construction, infiltration air is normally adequate to
provide air for combustion.
• Appliances located in confined spaces:
The confined space must be provided with two permanent openings, one commencing within 12 inches
(304.8mm) of the top and one commencing within
12 inches (304.8mm) of the bottom of the enclosure.
Each opening must have a minimum free area of one
square inch per:
– 1000 Btu/hr (292.81 Watts) if all air is taken from
inside the building
– 2000 Btu/hr (585.62 Watts) if all air is taken from
the outside by horizontal ducts
– 4000 Btu/hr (1171.24 Watts)if all air is taken from
the outside by direct openings.
Or the confined space must be provided with one
permanent opening or duct that is within 12 inches
(304.8mm) of the ceiling of the enclosure. This opening
must have a minimum free area of one square inch per:
– 3000 Btu/hr (878.43 Watts) if all air is taken from
the outside by a direct opening.
Louvers, grills and screens have a blocking effect, when
used, increase the sizes of your openings by 400% for
wood louvers (as wood type will reduce the free air by
75%) and 135% for metal louvers (as metal will reduce
the free air by 30%). Refer to the National Fuel Gas
Code for complete information. In buildings of tight
construction all air should be taken from outside.
Single pipe
Although it is permissible to draw combustion air from
the inside, it is not the manufacturer’s recommended
installation method. Always install a 3 inch elbow on the
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