Bosch GWH 2400 ES NG User manual

MODEL GWH 2400 ES NG and GWH 2400 ES LP -
INDOOR MODEL
Temperature Modulated with Electronic Ignition
Suitable for heating potable water only
Not approved for space heating purposes
(Intended for variable flow applications)
GWH 2400 ES NG - Natural Gas
GWH 2400 ES LP - Liquefied Petroleum (LP) Gas
6 720 608 782 US (2008.01) AL
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 neighbor’s
phone. Follow the gas supplier’s instructions
• Installation and service must be performed by a
qualified installer, service agency or the gas supplier.

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Index
Index
1Warning 3
2 Appliance details 4
2.1 Features 4
2.2 GWH 2400 ES Specifications
(Technical data) 4
2.3 Unpacking the GWH 2400 ES heater 5
2.4 General rules to follow for safe operation 6
2.5 Dimensions and Minimum installation
clearances 7
3 Installation instructions 8
3.1 Tools required for installation 8
3.2 Introduction 8
3.3 Venting 8
3.4 Combustion air requirements 15
3.5 Proper location for installing your heater 16
3.6 Heater placement and clearances 16
3.7 Mounting installation 16
3.8 Gas piping & connections 17
3.9 Water connections 20
3.10 Water quality 20
3.11 Recirculation application 21
3.12 Measuring gas pressure 21
4 Electrical connections 23
4.1 Electrical power supply 23
4.2 Position of the fuses in control unit 23
5 Operation instructions 24
5.1 LCD Display functions 24
5.2 For your safety read before operating
your water heater 25
5.3 Power 25
5.4 Temperature selection 25
5.5 Use of optional remote control accessory
(part no. TSTAT2) 26
5.6 Operation 26
5.7 Reset button 26
5.8 Program button 26
5.9 Locked condition 26
6 Maintenance and service 27
6.1 Annual maintenance 27
6.2 Winterizing for seasonal use 27
6.3 Mineral scale build-up 28
6.4 Adjusting CO2 (carbon dioxide) 28
6.5 Program values 31
6.6 Control board diagnostics 32
6.7 Fan speed adjustment 33
7 Troubleshooting 35
7.1 Introduction 35
7.2 Burner do not ignite when hot water
is turned ON 35
7.3 Water is too hot 35
7.4 Water is not hot enough 35
7.5 Low water flow/pressure 36
7.6 Hot water temperature fluctuates at tap 36
7.7 Noisy burner/heater during operation 36
8 Problem solving 38
8.1 Error code diagnostics 38
9 Electrical diagram 42
10 Sensor resistance charts 43
11 GWH 2400 ES Functional scheme 45
12 Interior components diagram
and parts list 46
12.1 Interior components 46
12.2 Components diagram 48
13 Protecting the environment 54
14 Limited Warranty 55

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Warning
3
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.
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.
Fig. 1
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, such as carbon monoxide
poisoning or fire.
Warning: Exhaust gas must be vented
to outside using stainless steel vent
material suitable for category III vent
systems and temperatures up to 480°F.
Vent 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. Approved vent terminators
must be used when penetrating to the
outside.
Warning: Place the 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 water
heater, unplug power supply cord from
outlet. Failure to do so could result in
severe personal injury or death.
Warning: The 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.

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Appliance details
2 Appliance details
2.1 Features
Parts
• Key Pad interface control
• High power pre-mix compact burner with low NOx
emissions
• Modulating Gas Valve with constant gas:air ratio
control
• Modulating water valve for improved comfort and
temperature control.
High quality materials for long working life
• Copper heat exchanger
• High efficiency Ceramat Burner
• Compact space saver: mounts on a wall with a
supplied bracket.
Features
• Real-time diagnostics for troubleshooting/
informational purposes
• LCD Display with backlight
• On/Off and Temperature control switches
• Reset button
• Program button (Selectable temperature default)
• Failure codes for easy diagnostics and repair
• Easily removable one-piece cover
• Built in freeze prevention.
Note: Freeze prevention is not intended to protect
plumbing outside the appliance or to keep the
appliance from freezing for long periods.
Accessories (Bosch part #)
• Optional wireless remote control accessory to
operate with the appliance (TSTAT2)
• Outdoor kit (AQOK).
2.2 GWH 2400 ES Specifications
(Technical data)
Approved in US/Canada
Capacity
Maximum flow rate: 6.4 GPM (24 l/min) at a 45°F
(25°C) rise.
Maximum output
147,000 Btu/h (43.0 kW)
Maximum input
175,000 Btu/h (51.2 kW)
Efficiency in %
Thermal efficiency > 82%
Min. Input
19,900 Btu/h (5.8 kW)
Temperature Control
Selection range: 100°F (38°C) - 140°F (60°C)
Default temperature: 122°F (50°C)
Stability: +/- 2°F (+/- 1°C)
Gas Requirement
Gas connection (inches) - ¾”
Inlet gas pressure under operation (with a high hot
water flow rate)*
• Propane: 8” - 13” water column
• Natural Gas: 3.5” - 10.5” water column.
* To measure gas pressure, see Measuring Gas
Pressure, chapter 3.12.
Water
• Hot water connection (inches) - ¾”
• Cold water connection (inches) - ¾”
• Water valve material: Polymer (PPS) (Polypropylene
Sulfid)
• Minimum water flow: 0.65 gallon/minute (2,5 l/m).
Note: Activation varies with inlet water temperatures
from 0.65 - 1.6 gallon/minute.
• Minimum recommended water pressure: 30 PSI
(2.07 bar)
• Minimum recommended well pressure: 40 PSI (2.75
bar), see chapter 3.9.
• Connections:
– Bottom of heater
Combustion
•NOx≤55 ppm
•CO≤250 ppm (measured)
•CO
2level set from factory, see chapter 6.4.
Dimensions
• Depth (in): 11¼” (286 mm)
• Width (in): 17 7/8” (452 mm)
• Height (in): 30½” (775 mm)
• Weight: 67 pounds (30,5 kg).
Gas types
Natural Gas.
LP Gas.
Converting the gas type can only be done by a certified
gas technician with a calibrated CO2analyzer.
iBOSCH is constantly improving its
products, therefore specifications are
subject to change without prior notice.

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Appliance details
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Call Bosch Water Heating through Bosch
thermotechnology corporation for conversion
instructions.
Voltage
120 V AC (60 Hz) nominal
Amperage
Idle - 40 mA
Operation - ≤2.5 A
Noise
45 - 65 db (A)
Safety devices
• Flame failure device (ionization flame rod sensor)
• Pressure relief valve (supplied with heater)
• Over heat prevention (temperature limiter)
• Inlet temperature sensor
• Outlet temperature sensor
• Backflow temperature sensor.
Water protection
IP X4 (protection against water drops)
2.3 Unpacking the GWH 2400 ES
heater
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.
Fig. 2 Rating plate
ASerial number
BType of gas
The box includes:
• GWH 2400 ES
• Pressure relief valve (150 psi / 200,000 Btu rating)
• Bracket for wall hanging the heater
• Exhaust vent adaptor (with 4 screws and gasket
provided)
• Combustion air inlet adaptor (with 3 screws and gas-
ket provided)
• Installation manual (manual can be downloaded at
www.boschhotwater.com)
• Product registration card
• Energy Guide label.
Please complete and return the enclosed product
registration card.
The GWH 2400 ES is not approved or designed
for:
• Manufactured (mobile) homes, boats or any mobile
installation (modular homes are acceptable for
installation)
• Use above 4500ft A.S.L. altitude
• Outdoor installation without installation of Outdoor
kit (AQOK)
• Space heating purposes
• Preheated inlet water supply.
iIf appliance is installed at elevations
between 2000ft and 4500ft, a
combustion gas analyzer is required for
proper calibration of appliance. (see page
22).

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Appliance details
To remove front cover
BLoosen the two Philips head screws located on
bottom rear of cover (see Fig. 3).
Fig. 3 Loosen the two screws
BLift front cover panel upward and remove.
Fig. 4 Removing the front cover
To remove combustion cover (service only)
BOpen the four clips and remove the combustion
cover see Fig. 5.
Fig. 5 Remove the combustion cover
2.4 General rules to follow for safe
operation
B1. 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.
B2. 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 occur, such as carbon monoxide
poisoning or fire.
B3. When the unit is installed indoors and ROOM
SEALED (twin pipe) it is permitted to be located in
bathrooms, bedrooms and occupied rooms that are
normally kept closed. See chapter 3.3 (page 8). 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 Fuel
Gas Code does not allow UNSEALED gas fired
water heater installations in bathrooms,
bedrooms or any occupied rooms normally
kept closed. See chapter 3.5 (page 16) and 3.4
(page 15).
B4. You must vent your heater. See chapter 3.3 on
VENTING.
B5. 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).
B6. Keep water heater area clear and free from
combustibles and flammable liquids. Do not locate
the heater over any material which might burn.
B7. Correct gas pressure is critical for the proper
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. See
Section 3.8, page 17.
B8. 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 heater but must be field
installed.
B9. 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.
B10. Failure to install heater correctly may lead to
unsafe operation and void the warranty.

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Appliance details
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2.5 Dimensions and Minimum installation clearances
Fig. 6 Dimensions
1On/Off button
2Reset button
3Program key
4Power ON or stand-by LED
5LCD display
6Up button
7Down button
Fig. 7 Minimum clearances
Note: For servicing access, a 2ft clearance to front
cover is recommended.
Model GWH 2400 ES
TOP (A) 12”
FRONT (B) 1”
BACK 0”
SIDES 1”
FLOOR (C) 12”
Table 1 Minimum clearances

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Installation instructions
3 Installation instructions
3.1 Tools required for installation
• Philips head screwdriver
• Flat head screwdriver
• Adjustable wrench
• Level
• Thermometer
• Standard plumbing tools
•Manometer
• Drill
• Pipe wrench
• Adjustable pliers
• Pipe fitting tools
• Hacksaw with metal blades
•Holesaw.
3.2 Introduction
Please follow these instructions. Failure to follow
instructions may result in:
BDamage or injury.
BImproper operation.
BLoss of warranty.
If you are unable to perform the tasks required to install
this heater properly, please contact a locally licensed
plumber or gas technician.
Common installation practice is to determine the
venting/intake system layout and penetration and then
work back to the heater.
3.3 Venting
3.3.1 Vent material and specifications
Establish vent clearances that comply with the vent
manufacturer's specifications. In all cases, follow local
codes. See Table 2.
The appliance should be located as close to the point
of vent termination as possible. The maximum vent
length is 26 feet (8 m) with one 90 degree elbow and
approved terminator. Subtract 2.5 feet from the total
vent length for each additional 90° elbow used (a
maximum of three 90° elbows are permitted in the
total exhaust vent length), or subtract 1.25 feet for every
45° elbow used. Horizontal sections of vent must pitch
Warning: Do not reduce the vent
(exhaust and combustion) pipe sizes
and do not common vent with any other
vented appliance or stove.
Warning: Failure to vent the exhaust
gases to the outside with sealed
stainless steel vent pipe (AL29-4C)
may result in dangerous flue gases
filling the structure in which it is
installed.
Warning: Do not mix vent pipe or
joining methods from different
manufacturers.
Warning: Proper end terminal / rain
cap must be used. Failure to do so may
result in damage to the appliance.
This damage is not covered under
the manufacturer's warranty.
Caution: The vent system must be
installed by a qualified installer in
accordance with these instructions. If
improperly installed, a hazardous
condition such as explosion or carbon
monoxide poisoning could result.
Bosch Water Heating will not be
responsible for improperly installed
appliances.
Warning: In areas where outside
temperatures routinely come close to
freezing, sealed combustion operation
is required. Use a concentric
termination or separate terminations for
combustion and vent, which must be
installed on the same wall or roof
surface, however never facing the
direction of prevailing winds. Failure to
do so may result in heat exchanger
freezing up and bursting. This failure is
not covered under the manufacturer's
warranty.
Diam. Min.
lenght
Max.
length
Material
Exhaust
Vent
3 or 4
inches
3 feet 26 feet with
1 90° elbow
and terminal
Sealed single wall
stainless steel
(AL29-4C)
Intake
Vent
3 or 4
inches
1 90°
elbow
26 feet with
1 90°elbow
and terminal
Sealed PVC or
any other rigid
pipe
Table 2 Venting Specifications

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Installation instructions
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upwards towards termination ¼" for every foot of
horizontal length, to prevent the pooling of condensate,
and be supported at 4 foot intervals with overhead
hangers.
Exception: horizontal run between last elbow
and termination must pitch down to termination
1/4" per foot.
Note: For horizontal terminations, venting must
terminate once it penetrates to the outside of the
structure. There must be no sections of vent pipe
exposed to the outdoors.
Note: Listed thimbles or collars are necessary where
venting passes through wall and ceiling partitions. If the
vent system passes through combustible areas where
the vent clearance requirements cannot be maintained,
it is permissible to chase straight sections of sealed 3
inch single wall vent through 4 inch (or greater) Type-B
vent. The distance to combustibles using this chase
technique is 1 inch1). Note: Type-B vent must never
be used as the actual exhaust vent system for the
appliance, as it is not gas tight and illegal for use
with this appliance. This will create a serious
health hazard and void the warranty.
For specific questions concerning vent material, speci-
fications, usage or installation, please contact the vent
manufacturer directly.
Minimum exhaust vent length
Fig. 8
Maximum exhaust vent and combustion air inlet
lengths
Fig. 9 Maximum vent and combustion air lenghts
Note: reduce 2.5 ft for each 90° elbow used after the
first one, reduce 1.25 ft for each 45° elbow, see table 2,
page 8.
Refer to chapter 3.3.2, page 12 for condensate drain
requirements.
Vent Safety System
The GWH 2400 ES will shut down if inadequate
exhaust venting is detected or a lack of combustion air
is provided to the unit; see troubleshooting section on
page 35. See error code to confirm error, correct the
problem and then reset the heater before operating.
1) in all cases, follow local codes.
3”
VENTING
Z flex Protech Heat Fab
3”
Horizontal
Terminal
2SVSTB03 FSTB3 9390 TEE
3” Vertical
terminator 2SVSRCF03 FSRC3 5300CI
Table 3 Terminator Part Numbers
Fittings or Piping Equivalent
feet m
45 degree elbow 1.25 0.38
90 degree elbow 2.5 0.76
pipe per foot 1 0.30
Table 4 Friction Loss Equivalent in piping and fittings
Company Contact info
Z-flex www.z-flex.com
800-654-5600
ProTech Industries www.protechinfo.com
800-766-3473
Heat-Fab www.heatfab.com
800-772-0739
Table 5 Vent manufacturers
The maximum exhaust
vent and combustion air
inlet lengths with one
elbow are ≥26ft.

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Installation instructions
Recommended exhaust vent terminator position
Fig. 10
* Subject to local codes and anticipated snow level
** Other equipment that operates with a mechanical air inlet may require greater distances, reference manufacturer's instructions
NOTE: terminating exhaust vent under a deck is not permitted
Ref. Description Minimum distance
ADirectly below an opening; operable windows, doors and any non-
mechanical fresh air openings
36 in (twin pipe installation)
48 in (single pipe installation)
B
Below a gutter, sanitary pipework or eaves 24 in
Below a gutter, sanitary pipework or eaves, protected by metal
shielding 12 in
CFrom any internal corner 12 in
D* Above ground or snow pack 12 in
Above a paved sidewalk 7 ft
EFrom an opposing wall or structure facing the termination 24 in
From the relief valve of a Ip gas regulator 60 in
FFrom a terminator facing a terminator 48 in
GVertically between two exhaust vent terminators on the same wall 60 in
HHorizontally between two exhaust vent terminators on the same wall 36 in
I**
Horizontally and vertically from combustion air inlet of a twin pipe
system 36 in
From the gravity combustion air inlet any other equipment 6 ft
JFrom any external corner 12 in
KHorizontally from an opening; operable windows, doors and any non-
mechanical fresh air openings
12 in (twin pipe installation)
48 in (single pipe installation)
LVertically from a wall, roof slope, or obstruction (venting through a flat
or pitched roof)
see ABOVE THE ROOF
requirements on following page
Table 6