Bosch GWH-345-450-ESR-L, GWH-345-450-ESR-N User Manual
GWH 345/450 ESR
Temperature Modulated with Electronic Ignition
Suitable for heating and recirculating potable water
GWH-345/450-ESR-N - Natural Gas
GWH-345/450-ESR-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.
6 720 607 909 US (2008.02) JS
What to do if you smell gas
• Close gas valve. Open windows and doors, and
evacuate the building.
• 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
1Warning 2
2 Appliance details 4
2.1 Features 4
2.2 GWH-345/450-ESR Specifications (Technical data) 4
2.3 Unpacking the GWH-345/450-ESR heater 5
2.4 General rules to follow for safe operation 6
2.5 Dimensions and minimum installation clearances 7
2.6 Applications 8
2.7 Water quality 9
3 Installation instructions 10
3.1 Introduction 10
3.2 Proper location for installing your heater 10
3.3 Heater placement and clearances 10
3.4 Mounting installation 10
3.5 Combustion air requirements 11
3.6 Venting 13
3.6.1 Vent material and specifications 13
3.6.2 Vent connections and air inlet restrictors 14
3.6.3 Condensate drain requirements 17
3.6.4 Room sealed installation (Twin pipe) 17
3.6.5 Vertical terminations 18
3.6.6 Horizontal terminations 18
3.6.7 Exhaust vent configuration examples 21
3.7 Gas piping & connections 22
3.8 Measuring gas pressure 24
3.9
Checking restrictor plate size by measuring CO2 level value 24
3.10 Water connections 25
3.11 Electrical connections 25
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 3" single wall sealed
stainless steel vent pipe 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.
4 Operating instructions 27
4.1 Initial filling instructions 27
4.2 For your safety read before operating your water heater 27
4.3 Startup instructions 27
4.4 Power 28
4.5 Recirculating water temperature 28
4.6 Temperature and hot water flow 28
4.7 Freeze protection 28
4.8 Electrical diagram 29
5 Maintenance and service 30
5.1 Service mode 30
6 Troubleshooting 32
7 GWH-345/450-ESR Functional scheme 34
8 Interior components diagram and parts list 35
8.1 Interior components 35
8.2 Components diagram 36
8.3 Parts list 37
9 Protecting the environment 38
Warning: Place the recirculating water
heater in a location where water leaks
will do NOT DAMAGE 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.
10 Ten Year Limited Warranty 39
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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 (14” W.C.).
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
• LCD screen to display temperatures, burner
operation and error codes
• On/Off button and separate temperature controls for
domestic water heating and recirculating water
• Reset button
• Failure codes for diagnostics and repair
• Freeze prevention cycle.
BOSCH is constantly improving its
products, therefore specifications are
i
subject to change without prior notice.
Temperature Control
Selection range: 115°F (45°C) - 190°F (90°C)
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 single wall sealed stainless steel vent
pipe.
See chapter 3.6 for Venting.
Water
• Hot water connection - ¾” NPT
• Cold water connection - ¾” NPT.
Combustion
•NOx ≤ 100 ppm
•CO ≤ 250 ppm
•CO
level (see table 8 for correct restrictor
2
dimension).
2.2 GWH-345/450-ESR Specifications
(Technical data)
Approved in US/Canada
Capacity
GWH345 Maximum flow rate: 3.5 GPM (13 l/min) at a
45°F (25°C) rise.
GWH450 Maximum flow rate: 4.5 GPM (17 l/min) at a
45°F (25°C) rise.
Maximum output
GWH345 - 77,900 Btu/h (22.8 kW)
GWH450 - 98,400 Btu/h (28.8 kW)
Maximum input
GWH345 - 95,000 Btu/h (27.8 kW)
GWH450 - 120,000 Btu/h (35.1 kW)
Efficiency in %
GWH345 Combustion efficiency: 82%
GWH450 Combustion efficiency: 81%
Min. Output
GWH345 - 23,900 Btu/h (7 kW)
GWH450 - 35,500 Btu/h (10.4 kW)
Dimensions
• Depth (in): 11 ¾” (300 mm)
• Width (in): 15 ¾” (400 mm)
• Height (in): 27 ½” (700 mm)
• Weight: 47 pounds (21 kg).
Gas types
Natural Gas.
Liquid Propane.
The appliance is not field convertible.
Voltage
120 V AC (50/60 Hz)
Amperage
Idle - 40 mA
Operation - ≤ 1.5 A
Noise
≤ 50 db (A)
Safety devices
• Flame failure device (Ionization flame control)
• Overheat prevention (temperature limiter)
• Pressure switch (blocked vent protection).
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Appliance details
Water resistant
IP X4 (protection against water drops)
2.3 Unpacking the GWH-345/450-ESR
heater
This heater is packed securely.
The box includes:
• Wall-mounted gas fired recirculating water heater
• Bracket and screws for wall hanging the 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
• Pressure relief valve
• Inlet air restrictors
– GWH 345 ESR N: Ø38/40/42
– GWH 345 ESR LP: Ø38/40/42
– GWH 450 ESR N: Ø44/47/50/55
– GWH 450 ESR LP: Ø47/50/55/60
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 (Fig. 3).
Front cover
Low voltage
access cover
Control panel
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Fig. 3 Service position to access water and electric
connections
B Lift front cover upward and remove.
The GWH-345/450-ESR is not approved or
designed for:
• Manufactured (mobile) homes, RV's or boats
•Outdoor installation
• Combination venting with other appliances
• Closed loop heating applications.
5
Appliance details
2.4 General rules to follow for safe
operation
1. You must follow these instructions when you install
your 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 must conform with CGA
B149.(1,2) INSTALLATION CODES and /or local
installation codes.
2. Carefully plan where you install the 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.
3. When the unit is installed indoors with ROOM
SEALED (twin pipe) combustion air and venting, it is
permitted to be located in bathrooms, bedrooms and
occupied rooms that are normally kept closed. See
chapter 3.6. If the unit will be installed indoors and
use indoor combustion air, the place where you
install the heater must have enough ventilation. 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.
4. You must vent your heater. See chapter 3.6 Venting.
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 heater) during any
pressure testing at pressures in excess of ½ Psig
(3.5 kPa).
6. Keep water heater area clear and free from
combustibles and flammable liquids. Do not locate
the heater over any material which might burn.
7. Correct gas pressure is critical for the optimum
operation of this heater. Gas piping must be sized to
provide the required pressure at the maximum output
of the 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.
8. Should overheating occur or the gas supply fails 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 heater.
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.
10.Failure to install heater correctly may lead to unsafe
operation and void the warranty.
11.The heater must not be installed in an unheated area
where temperatures will reach 36°F or lower. If the
heater is left in an area susceptible to such
temperatures, drain the unit and disconnect from
electrical supply. See Chapter 4.7 for additional
freeze prevention information.
12.In areas where water supply has a high mineral
content, a water softener is strongly recommended.
A water softener is required if the water hardness
exceeds 6 grains/gal (103 mg/l) calcium carbonate.
Damage to the water heater resulting from hard
water/scale deposits will not be covered under
warranty.
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2.5 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 Recirculating water temperature selector
7 LED - (ON) warning light (blinks when in error lock out)
8 Domestic hot water temperature selector
9 Mounting plate
measuring point
2
Fig. 5 Minimum clearances
Model GWH-345/450-ESR
TOP 12”
FRONT (B) 4”
BACK 0”
SIDES ½”
BOTTOM 12”
Table 1 Minimum clearances
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Appliance details
2.6 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.
Pump Sizing
Required PS pumps are Taco 007 Bronze or Grundfos 15-42B. PZ pumps should be sized by a professional plumbing contractor based on the specific application.
Caution: Do not overpump the heater.
Maximum 5 gpm water flow permitted
through the heater.
Instantaneous water heater (direct tank load design)
Note: maximum amp draw:
1,5A. Do not connect
additional pump to the
appliance but use a relay panel
if powering multiple pumps.
Fig. 6
Front cover
Low voltage
access cover
Control panel
Fig. 7 Service position to access water and electric
connections
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Pressure drop curves
Note: Flow above 6 GPM is not permitted.
50 feet of head
GWH 345 ESR
40 feet of head
30 feet of head
20 feet of head
Inlet pressure
10 feet of head
Appliance details
0 feet of head
0 GPM 1 GPM 2 GPM 3 GPM 4 GPM 5 GPM 6 GPM
Fig. 8 GWH 345 ESR
50 feet of head
40 feet of head
30 feet of head
20 feet of head
Inlet pressure
10 feet of head
0 feet of head
0 GPM 1 GPM 2 GPM 3 GPM 4 GPM 5 GPM 6 GPM
Fig. 9 GWH 450 ESR
water flow rate
GWH 450 ESR
wate r flow rate
2.7 Water quality
Water quality can have an impact on appliance performance and appliance longevity, and may not be covered by the
manufacturer's warranty.
For water analysis data call your local water department. If on a well system, have well water analyzed periodically. If
water quality is exceeding one or more of the values specified below, Bosch recommends installing a water conditioner or softener.
Description
Max.
Levels
Table 2 Venting Specifications
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pH TDS
(Total
Total
hardness
Dissolved
Solids)
pH
range
mg/l or
ppm
mg/l or
ppm
6.5-8.5 500 100 (6
grains)
Aluminum Chlorides Copper Iron Manganese Zinc
mg/l or
ppm
mg/l or
ppm
mg/l or
ppm
mg/l or
ppm
mg/l or ppm mg/l or
ppm
0.2 250 1.0 0.3 0.05 5.0
9
Installation instructions
3 Installation instructions
3.1 Introduction
Please follow these instructions. Failure to follow
instructions may result in:
• Property damage or personal injury
•Improper operation
• Heater damage
• Loss of warranty.
Please contact Bosch Water Heating with any
questions.
3.2 Proper location for installing your
heater
Carefully select the location of the water heater. For
your safety and for proper heater operation, you must
provide combustion air to the heater and a proper
exhaust vent system.
Follow the guidelines below:
B 1. Locate the 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.
Warning: The water in this
recirculating 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 to prevent heater from freezing.
See chapter 9 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 heater. The appliance
area must be kept free of all
combustible materials, gasoline and
other flammable vapors and liquids.
3.3 Heater placement and clearances
The GWH-345/450-ESR is design certified for
installation on a combustible wall (see 3.4 Mounting
installation) provided the floor covering below the
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 sealed stainless
steel (AL29-4C) vent pipe (rated for Category III
appliances) must be used when exhaust venting this
appliance. See 3.6 Venting.
3.4 Mounting installation
Warning: before starting installation:
B check that there are no loose parts
inside the appliance
B check that the gas type of the 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
heater to a wall surface.
Warning: Do not install this appliance
on a carpeted wall. The heater must be
mounted on a wall using appropriate
anchoring materials.
10
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 heater should be kept level on the
wall surface. See Fig. 10.
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Installation instructions
Single pipe
Although it is permissible to draw combustion air from
inside the structure, it is not the manufacturer’s recommended installation method. Always install a 3 inch
elbow on the combustion air inlet to prevent foreign
objects from falling into the unit (see Fig. 11).
Fig. 10 Mounting the heater
3.5 Combustion air requirements
Warning: In areas where freezing
temperatures are common the twin pipe
system is recommended. In a single
pipe installation, 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
manufacturer’s 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-345/450-ESR is designed as a sealed
combustion appliance. It is recommended that the
combustion air be provided by a dedicated 3” pipe to
the outside. If terminating combustion air piping
horizontally, pitch vent down 1/4" per foot towards
termination to prevent rain from entering the appliance.
The combustion air pipe may be constructed of
aluminum flex, PVC or any other rigid or semi rigid
sealed pipe. The combustion air inlet must be located in
such a manner as to provide a minimum 3 foot
clearance from the exhaust vent terminator.
The maximum length of the combustion air inlet is 39
feet with one elbow. Subtract 6 feet for each additional
elbow. Maximum number of elbows permitted is 4.
Fig. 11
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) of air required for the GWH-345/
450-ESR alone.
– b) In unconfined spaces in buildings of
conventional frame, masonry, or metal
construction, infiltration air is normally adequate to
provide air for combustion.
– c) Installations in structures that have been tightly
constructed (air infiltration rate of 0.40 ACH or
less) must provide combustion air per the National
Fuel Gas Code. Consult an HVAC specialist if
your air infiltration rate is questionable. For these
types of installations, the twin pipe system must be
used.
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Installation instructions
• 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.
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