Bosch GWH 2400 ES NG, GWH 2400 ES LP 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

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 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.

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

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

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

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

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, 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.

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.

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.

Fig. 1

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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).

BOSCH is constantly improving its products, therefore specifications are

subject to change without prior notice.

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

level set from factory, see chapter 6.4.

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)

Dimensions

• Depth (in): 11¼” (286 mm)

• Width (in): 17

• 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 CO

” (452 mm)

analyzer.

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Appliance details

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)

If appliance is installed at elevations between 2000ft and 4500ft, a

combustion gas analyzer is required for proper calibration of appliance. (see page

22).

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

A Serial number B Type 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

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• 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.

Appliance details

To remove front cover

B Loosen the two Philips head screws located on

bottom rear of cover (see Fig. 3).

Fig. 3 Loosen the two screws

B Lift front cover panel upward and remove.

Fig. 4 Removing the front cover

To remove combustion cover (service only)

B Open the four clips and remove the combustion

cover see Fig. 5.

2.4 General rules to follow for safe operation

B 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.

B 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 occur, such as carbon monoxide poisoning or fire.

B 3. 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 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

(page 15).

B 4. You must vent your heater. See

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 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 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.

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 heater but must be field installed.

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.

3.3 (page 8). If the

3.5 (page 16) and 3.4

chapter 3.3 on

Fig. 5 Remove the combustion cover

B 10. Failure to install heater correctly may lead to

unsafe operation and void the warranty.

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2.5 Dimensions and Minimum installation clearances

Appliance details

Fig. 6 Dimensions

1 On/Off button 2 Reset button 3 Program key 4 Power ON or stand-by LED 5 LCD display 6 Up button 7 Down 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

•Hole saw.

3.2 Introduction

Please follow these instructions. Failure to follow instructions may result in:

B Damage or injury. B Improper operation. B Loss 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

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.

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.

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)

Exhaust Vent

Intake Vent

Diam. Min.

lenght

3 or 4

inches

3 or 4

inches

3 feet 26 feet with

1 90° elbow

Max.

length

1 90° elbow and terminal

26 feet with 1 90°elbow

and terminal

Material

Sealed single wall

stainless steel

(AL29-4C)

Sealed PVC or

any other rigid

pipe

may result in dangerous flue gases filling the structure in which it is installed.

Table 2 Venting Specifications

The appliance should be located as close to the point

Warning: Do not mix vent pipe or joining methods from different manufacturers.

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

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Installation instructions

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 inch

. 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.

3”

VENTING

3”

Horizontal

Terminal

3” Vertical terminator

Z flex Protech Heat Fab

2SVSTB03 FSTB3 9390 TEE

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

For specific questions concerning vent material, specifications, usage or installation, please contact the vent manufacturer directly.

Minimum exhaust vent length

Fig. 8

Maximum exhaust vent and combustion air inlet lengths

The maximum exhaust vent and combustion air inlet lengths with one elbow are ≥ 26ft.

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.

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

1) in all cases, follow local codes.

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Installation instructions

Recommended exhaust vent terminator position

Fig. 10

Ref. Description Minimum distance

C From any internal corner 12 in

F From a terminator facing a terminator 48 in

G Vertically between two exhaust vent terminators on the same wall 60 in

H Horizontally between two exhaust vent terminators on the same wall 36 in

I**

J From any external corner 12 in

Directly below an opening; operable windows, doors and any nonmechanical fresh air openings

Below a gutter, sanitary pipework or eaves 24 in

Below a gutter, sanitary pipework or eaves, protected by metal shielding

Above ground or snow pack 12 in

Above a paved sidewalk 7 ft

From an opposing wall or structure facing the termination 24 in

From the relief valve of a Ip gas regulator 60 in

Horizontally and vertically from combustion air inlet of a twin pipe system

From the gravity combustion air inlet any other equipment 6 ft

Horizontally from an opening; operable windows, doors and any nonmechanical fresh air openings

36 in (twin pipe installation)

48 in (single pipe installation)

12 in

36 in

12 in (twin pipe installation)

48 in (single pipe installation)

Vertically from a wall, roof slope, or obstruction (venting through a flat or pitched roof)

see ABOVE THE ROOF

requirements on following page

Table 6

* 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

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Venting configuration examples

Fig. 11 Horizontal side wall venting installation

(combustion air piping not shown)

Installation instructions

Fig. 13 Above the roof clearance requirements from

rain cap (combustion air piping not shown)

Important: Note: Pitch horizontal runs down toward the

heater, except horizontal run between last elbow and termination which must slope 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.

Fig. 12 Vertical venting installation (combustion air

piping not shown)

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Fig. 14 Vertical venting installation - Masonry

Chimney (combustion air piping not shown)

Installation instructions

3.3.2 Condensate drain requirements

A condensate drain must be installed under the following conditions:

• All vertical terminating vent installations

• Horizontal terminating vent installations where the total equivalent exhaust vent length is greater than 10 feet. See table 17, page 33.

• Vent installations where any section of the exhaust vent pipe passes through an unconditioned space.

Note: Do not install condensate drain in areas where it may freeze.

1. Install condensate drain as close to heater as

possible.

2. Use 3/8" ID high temperature silicone tube to

connect to condensate drain port. Do not use copper piping for any portion of the condensate drain.

3. Form a condensate trap by means of a 3" loop

partially filled with water.

4. To increase the tube length, connect to end of the

high temperature silicon tubing with vinyl tubing, PVC or CPVC pipe. Do not reduce the internal diameter at any point.

5. Dispose of condensate according to local codes.

Room sealed installation (TWIN PIPE SYSTEM)

Installing this water heater as a room sealed (TWIN PIPE SYSTEM) is the recommended method. Contact your dealer for available vent termination kits and vent materials for this water heater. The exhaust and combustion air piping must vent directly to the outside of the structure.

Fig. 15 Condensate drain installation

3" Venting Z-flex ProTech Heat Fab

90° Condensate Drain Tee

Horizontal Condensate Drain

Condensate Drain Tube

2SVEVWCF03 FST3 &

FSDF3

2SVEDWCF03 FSHDT3 9321

2SVEDTK24 N/A 7000TUBE

93PPLSTEE

Table 7 Approved Condensate Drain Part Numbers

Fig. 16

Combustion air pipe: ≤ 26 ft (8 m) from collar Exhaust vent pipe: ≤ 26 ft (8 m) from collar

Fig. 17

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Installation instructions

Warning: Approved terminators must

be used for inlet and exhaust vent systems to prevent rain from entering the appliance, failure to do so may result in damage to the appliance. This failure is not covered under the manufacturer’s warranty.

first one, reduce 1.25 ft for each 45° elbow. A maximum of three 90-degree elbows are permitted.

Determining installation adjustment

The GWH 2400 ES comes factory set to accomodate most common venting arrangements. Determine the elbows and straight pipe you will require for exhaust and combustion air. Refer to the the table below to determine if the factory setting for the fan is adequate. If your venting system is longer and exceeds the values listed in Table 8, proceed to Section 6.7, page 33 for fan speed adjustment.

TWIN PIPE

Exhaust

Intake

1 x 90° elbow or Less

2 x 90° elbow

One 90° elbow

or Less (feet)

Two 90°

elbows

19’ 16.5’ 14’

16.5’ 14’ 11.5’

Three 90°

elbows

Fig. 18

Open combustion installation (SINGLE PIPE SYSTEM)

Not recommended in cold climate areas, see chapter 3.4, page 15.

Fig. 19

Connecting a one piece 90 degree elbow pipe to the combustion air inlet adaptor is required. This will prevent debris or objects from falling into the appliance.

The exhaust vent system must vent directly to the outside of the building and an adequate amount of indoor combustion air must be provided for this installation. See chapter 3.4. Note: reduce 2.5 ft for each 90° elbow used after the

3 x 90° elbow

SINGLE PIPE

No intake piping

14’ 11.5’ 9’

19’ 16.5’ 14’

Maximum combined intake and exhaust vent length without

fan speed

adjustment.

Table 8

Note: Maximum of three 90° elbows allowed for exhaust and three 90° elbows allowed for intake.

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Installation instructions

3.3.3 Vent connections

B Attach the flue gas exhaust accessory (8 705 504

151) to the top of the unit (position 1) using the 4 screws and gasket provided. Fully insert stainless steel vent pipe 1.5” minimum into the accessory and tighten the clamp (position 2).

Fig. 20

B Attach the combustion air inlet accessory (8 705

504 154) to the top of the unit (position 3) using the 3 screws and gasket provided, and install air intake pipe over the accessory. NOTE: The appliance has the option to mount the combustion air inlet accessory on the top right or on the top left side of the heater. The combustion air inlet that is not used must be kept sealed.

Fig. 21

B Ensure that exhaust vent pipe is fully inserted in collar

to enable proper connection.

Exhaust venting must be 3" or 4" sealed single wall stainless steel (AL29-4C) vent

pipe.

Attention residents of the Commonwealth of Massachusetts:

In the Commonwealth of Massachusetts the following regulation went into effect on 12/30/2005:

(a) For all side wall horizontally vented gas fueled equipment installed in every dwelling, building or structure used in whole or in part for residential purposes, including those owned or operated by the Commonwealth and where the side wall exhaust vent termination is less than seven (7) feet above finished grade in the area of the venting, including but not limited to decks and porches, the following requirements shall be satisfied:

1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At the time of installation of the side wall horizontal vented gas fueled equipment, the installing plumber or gasfitter shall observe that a hard wired carbon monoxide detector with an alarm and battery back-up is installed on the floor level where the gas equipment is to be installed. In addition, the installing plumber or gasfitter shall observe that a battery operated or hard wired carbon monoxide detector with an alarm is installed on each additional level of the dwelling, building or structure served by the side wall horizontal vented gas fueled equipment. It shall be the responsibility of the property owner to secure the services of qualified licensed professionals for the installation of hard wired carbon monoxide detectors.

a. In the event that the side wall horizontally vented gas fueled equipment is installed in a crawl space or an at tic, the hard wired carbon monoxide detector with alarm and battery back-up may be installed on the next adjacent floor level.

b. In the event that the requirements of this subdivision can not be met at the time of completion of installation, the owner shall have a period of thirty (30) days to comply with the above requirements; provided, however, that during said thirty (30) day period, a battery operated carbon monoxide detector with an alarm shall be installed.

2. APPROVED CARBON MONOXIDE DETECTORS. Each carbon monoxide detector as required in accordance with the above provisions shall comply with NFPA 720 and be ANSI/UL 2034 listed and IAS certified.

3. SIGNAGE. A metal or plastic identification plate shall be permanently mounted to the exterior of the building at a minimum height of eight (8) feet above grade directly in line with the exhaust vent terminal for the horizontally vented gas fueled heating appliance or equipment. The sign shall read, in print size no less than one half (1/2) inch in size, "GAS VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS".

4. INSPECTION. The state or local gas inspector of the side wall horizontally vented gas fueled equipment shall not approve the installation unless, upon inspection, the inspector observes carbon monoxide detectors and

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Installation instructions

signage installed in accordance with the provisions of 248 CMR 5.08(2)(a)1 through 4.

(b) EXEMPTIONS: The following equipment is exempt from 248 CMR 5.08(2)(a)1 through 4:

1. The equipment listed in Chapter 10 entitled "Equipment Not Required To Be Vented" in the most current edition of NFPA 54 as adopted by the Board; and

2. Product approved side wall horizontally vented gas fueled equipment installed in a room or structure separate from the dwelling, building or structure used in whole or in part for residential purposes.

(c) MANUFACTURERS REQUIREMENTS - GAS EQUIPMENT VENTING SYSTEM REQUIRED. When the manufacturer of Product Approved side wall horizontally mounted gas equipment provides a venting system design or venting system components with the equipment, the instructions provided by the manufacturer for the installation of the equipment and the venting shall include:

1. Detailed instructions for the installation of the venting system or the venting system components: and

2. A complete parts list for the venting system design or venting system.

(d)MANUFACTURER REQUIREMENTS - GAS EQUIPMENT VENTING SYSTEM NOT PROVIDED. When the manufacturer of a product approved side wall horizontally vented gas fueled equipment does not provide the parts for the venting of flue gases, but identifies "special venting systems," the following requirements shall be satisfied by the manufacturer:

1. The referenced "special venting system" instructions shall be included with the appliance or equipment installation instructions; and

2. The "special venting systems" shall be product approved by the Board, and the instructions for that system shall include a parts list and detailed installation instructions.

(e) A copy of all installation instructions for all products approved side wall horizontally vented gas fueled equipment, all venting instructions, all parts lists for venting instructions, and/or all venting design instructions shall remain with the appliance or equipment at the completion of the installation.

3.4 Combustion air requirements

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.

Warning: When installed in an environment where corrosive chemicals or dirty air are present the twin pipe system is required.

Twin pipe

The GWH 2400 ES is designed as a sealed combustion appliance. It is recommended that the combustion air be provided by a dedicated 3” or 4” pipe from the outside. The combustion air pipe may be PVC or any other rigid sealed 3” or 4" pipe. The combustion air piping must pitch down 1/4 inch per foot towards termination to prevent rain water from entering the appliance. The combustion air inlet, whether terminating vertically or horizontally, must be located in such a

manner as to provide a minimum 3 foot clearance from the exhaust vent terminator. See Fig. 10 Letter I, page 10. The maximum length of the combustion air inlet is 26 feet with one elbow. Subtract 2.5 feet for each additional 90° elbow and 1.25 feet for each additional 45° elbow. Maximum number of elbows permitted is 3.

Warning: Vent terminations must

prevent rain from entering the combustion air and exhaust vent piping.

Single pipe Note: This appliance requires 8750 cubic feet of

available combustion air, or a minimum of 1094 square feet of space with an 8 foot ceiling to operate. If the large amount of air space, which equates to about half of most average sized homes, is not available, the appliance must pull air from outside (see twin pipe system above).

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 top of the combustion air inlet adaptor to prevent foreign objects from falling into the unit. If a single pipe installation is utilized, follow guidelines

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Installation instructions

below for providing adequate combustion air for the water heater as well as any other appliances that may consume air in the space. Always follow local codes if they are more stringent.

This Installation Manual specifies the minimum exhaust vent length (Fig. 8, page 9) 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 the other combustion appliances in the building are not supplied with sufficient combustion air. A wood stove or furnace can pull its combustion air from the heater's vent pipe, allowing the cold incoming air to freeze the cold water in the heat exchanger. Supplying more combustion air for all combustion appliances is the solution. A HVAC specialist should be consulted to design solutions for providing more combustion air. Observe the following guidelines: Installations in structures that have been tightly constructed (air infiltration rate of 0.40 ACH or less) must be provided with combustion air per the National Fuel Gas Code. Consult a HVAC specialist if your air infiltration rate is questionable. The space must have 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.

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 and

insulated to save energy. Centrally locating the water heater is recommended to keep hot water distribution times even throughout the structure.

Warning: The water in this water heater is cold and always remains cold except for the times the burner is on. In the event of power outage in conjunction with freezing temperatures, it is recommended that the heater be drained. See chapter 6.2, page 27 “Winterizing” 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.

3.6 Heater placement and clearances

The GWH 2400 ES is approved for installation on a combustible wall (see chapter 3.7 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. 7 and Table 1 on page 7.

Or the 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 300% if your louvers are wood and by 43% if your louvers are metal. Refer to the National Fuel Gas Code for complete information.

3.5 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:

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 chapter 3.3 (page 8) Venting.

3.7 Mounting installation

Warning: before starting installation

B Check that there are no loose or

damaged parts inside the appliance

B Confirm the gas type of the heater

matches the gas supply you will be connecting the heater, see Fig. 2,

page 5.

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Front cover should be removed (see instructions on page 6) in order to inspect

components visually.

Warning: Do not install this appliance on a carpeted wall. The heater must be mounted on a wall using appropriate anchoring materials.

If wall is sheathed with plaster or drywall, it is recommended that two support boards, either 1”x4” or 1/2" (minimum) plywood first be attached across a pair of studs, see Fig. 22.

B Secure the wall mounting bracket provided with the

heater to the wall surface. The heater must be kept level on the wall surface (see Fig. 23).

B Hang the appliance on the bracket, see Fig. 24.

Installation instructions

Fig. 23 Leveling the mounting bracket on the studs

Studs 16"

(406mm) on

center

Fig. 22 Distance between support boards

Fig. 24 Mounting the heater

Warning: Appliance must be installed vertically.

3.8 Gas piping & connections

Before connecting the gas supply, check the rating plate on the right side of the heater 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 must conform to CSA B149

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Installation instructions

INSTALLATION CODES and/or local installation codes.

Warning: DO NOT connect to an unregulated or high pressure propane line or to a high pressure commercial natural gas line.

Warning: The heater must be isolated from the gas supply piping system during any pressure testing of that system at test pressures equal to or more than 0.5 psig. If overpressure has occurred, such as through improper testing of the gas lines or malfunction of the supply system, the gas valve must be checked for safe operation.

GAS CONNECTIONS

B Install a manual gas shut off valve on the gas supply

line within easy reach of the appliance.

B Install a union when connecting gas supply. B The minimum internal diameter required for

any appliance connector is ¾”.

Danger: If you have a leak, shut off the

gas. Tighten appropriate fittings to stop leak. Turn the gas on and check again with a gas leak detection solution. Never test for gas leaks using a match or flame.

GAS LINE SIZING

The gas supply piping for a single heater should be sized for a maximum draw of 199,000 BTUH. Measure the length of gas supply line and use the tables in Fig. 27, page 19 or the gas line manufacturer’s sizing tables to determine the pipe diameter necessary to accommodate the 199,000 BTU demand of the heater. If there are more gas appliances on the line, size the gas line according to the total maximum amount of BTU input rating for all appliances.

Note: Undersizing the gas line may result in diminished hot water flow rate and temperature. See chapter 3.12, page 22 for the procedure to confirm gas pressure. Proper gas pressure must be confirmed at time of installation.

B Undersized flexible appliance connectors not

permitted.

B National Fuel Gas Code requires that a sediment

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, see Fig. 25.

Minimum

3”

Cap

Gas supply

Fig. 25 Gas connection (drip leg)

Once connections are made, check for gas leaks at all joints. Apply some gas leak detection solution to all gas fittings. Bubbles are a sign of a leak. A combustible gas detector may also be used to detect for leaks.

Fig. 26

Gas piping

Inlet gas particle screen (included)

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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 2400 ES (example: ¾” B.I. Natural Gas pipe for 10 ft (3.0m). will handle 278,000 btu’s (81.5 kWh). For multiple appliances combine the total maximum btu input load and then refer to applicable chart below.

Nominal

Iron

Pipe Internal

Size, Diameter

inches inches 10 20 30 40 50 60 70 80 90 100 125 150 175 200

1/4 0.364 32 22 18 15 14 12 11 11 10 9 8 8 7 6

3/8 0.493 72 49 40 34 30 27 25 23 22 21 18 17 15 14

1/2 0.622 132 92 7363 56504643403834 312826

3/4 0.824 278 190 152 130 115 105 96 90 84 79 72 64 59 55

1 1.049 520 350 285 245 215 195 180 170 160 150 130 120 110 100

1 1/4 1.380 1050 730 590 500 440 400 370 350 320 305 275 250 225 210

1 1/2 1.610 1600 1100 890 760 670 610 560 530 490 460 410 380 350 320

2 2.067 3050 2100 1650 1450 1270 1150 1050 990 930 870 780 710 650 610

Length of Black iron Pipe , Feet

Length of Flexible Corrugated Stainless Steel Tubing (CSST), Feet

Tube size, inches EHD*

1/2 18 EHD 82 58 47 41 37 34

3/4 23 EHD 161 116 96 83 75 68

1 30 EHD 330 231 188 162 144 131

1 1/4 37 EHD 639 456 374 325 292 267

10 20 30 40 50 60

* EHD = Equivalent Hydraulic Diameter. The greater the value of EHD, the greater the gas capacity of the tubing

FOR LP GAS

Maximum Capacity of Pipe in Thousands of BTU per Hour of Undiluted Petroleum Gases (at 11 inches Water Column Inlet Pressure) (Based on a Pressure Drop of 0.5 Inch Water Column).

* EHD = Equivalent Hydraulic Diameter. The greater the value of EHD, the greater the gas capacity of the tubing.

Nominal

iron

pipe

Inches

10 20 30 40 50 60 80 100 125 150 200

1/2 291 200 160 137 122 110 94 84 74 67 58

3/4 608 418 336 287 255 231 197 175 155 140 120

1145 787 632 541 480 434 372 330 292 265 227

Black Iron Pipe Length of Pipe, Feet

Length of Flexible Corrugated Stainless Steel Tubing (CSST), Feet

Tube size inches EHD*

10 20 30 40 50 60

1/2 18 EHD 129 91 74 64 58 53

3/4 23 EHD 254 183 151 131 118 107

1 30 EHD 521 365 297 256 227 207

Maximum Capacity of Semi-Rigid (flexible, non corrugated) Tubing in Thousands of BTU per Hour of Undiluted Liquefied Petroleum Gases (at 11 inches Water Column Inlet Pressure).

(Based on a Pressure Drop of 0.5 Inch Water Column)

* Source National Fuel Gas Code NFPA 54, ANSI Z223.1 - No Additional Allowance is necessary for an ordinary number of fittings

Fig. 27

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Outside Length of Tubing, Feet diameter Inch 10 20 30 40 50 60 70 80 90 100

3/8 39 26 21 19

1/2 9262 50 41 37 3531292726

5/8 199 131 107 90 79 72 67 62 59 55

3/4 329 216 181 145 131 121 112 104 95 90

Copper

_ _____

Installation instructions

3.9 Water connections

Warning: This heater is not approved

for preheated water applications. See chapter 3.11 for approved recirculating application.

B When facing the heater, the ¾” cold connection is on

the bottom right and the hot connection is on the bottom left. Centrally locating the water heater is recommended to keep hot water distribution times even throughout the structure.

COLD

HOT

3.10 Water quality

Water quality can have an impact on appliance longevity and may not be covered under the manufacturer's warranty. For water analysis data call your local water department, or if on a well, have well water analyzed periodically. If water quality exceeds one or more of the values specified below, Bosch recommends installing a water conditioner or softener.

Description Max. Levels

pH pH 6.5 - 8.5

TDS (total Dissolved Solids)

Total hardness mg/l or ppm

Aluminum mg/l or ppm 2.0

Chlorides mg/l or ppm 250

mg/l or ppm 500

100

(6 grains)

Fig. 28

B The use of unions when connecting both water

pipes to the inlet and outlet connections is required. This will facilitate any necessary servicing.

B Plastic or PEX type plumbing line materials are not

suitable for connecting directly to the water heater.

B Although water piping throughout the building may

be other than copper, we recommend that copper or suitably rated stainless steel flex line piping be used for the water connections for 1.5’ on either side of the water heater (follow local codes if more stringent).

B Never sweat any piping directly to or beneath

the water connections, as damage can occur to the internal water valve from heating of the pipe.

B Keep water inlet and outlet pipes to no less

than ¾" (19.05mm) diameter to allow the full flow capacity.

B If the cold and hot connections to the heater are

reversed, the heater will not function. Be certain there are no loose particles or dirt in the piping. Blow out or flush the lines before connecting to the water heater.

B Full port shutoff valves should be installed on both

the cold water supply and hot water outlet lines to facilitate servicing the heater (see Fig. 29).

B For installation on a private well system with the use

of a pressure tank, the lowest pressure range setting recommended is 40-60 psi (2.75 and 4.15 bar).

Copper mg/l or ppm 1.0

Iron mg/l or ppm 0.3

Manganese mg/l or ppm 0.05

Zinc mg/l or ppm 5.0

Table 9

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Installation instructions

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 a minimum of 4” above a drain and installed such that it allows complete drainage of both the PRV and the line. The discharge line must be placed where it will not cause any damage. 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. 29. 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.

3.11 Recirculation application

The following drawing is provided to outline one possible recirculation design using the water heater in conjunction with an Ariston mini tank water heater. Recirculation directly through the tankless water heater not allowed. This schematic is for illustration only and must not be used for actual installation without appropriate engineering and technical advice from a properly licensed professional in the locality where the installation is made.

GWH

2400

Ariston Minitank

Fig. 29 Plumbing Connections (with shutoff valves)

and Pressure Relief Valve

1 Water filter

Fig. 30 Recirculation application

1 Full port isolation valve 2 Circulator (pump) 3 Check valve 4 PRV 5 Expansion tank

The use of a small electric mini-tank water heater (4-6 gallon size) should be used for this application and designed so the pump will circulate the water through the mini-tank and the building's hot water return loop only. Timed or thermostatically controlled operation of the pump is commonly done. Contact Bosch Water Heating if further information is needed.

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Installation instructions

3.12 Measuring gas pressure

Confirm gas pressure upon installation.

Connecting manometer

B Shut off gas supply at installer supplied shutoff valve

for this water heater.

B Remove front cover and locate inlet gas pressure

measuring point (see Fig. 32).

B Loosen screw inside left test point fitting (do not

remove) and connect manometer tube to test point. Remove screw completely if correct size tapping is available.

Static Pressure Test

B Turn gas supply back on. B Record static gas pressure reading in table 11.

Operating Pressure Test

B Press ON/OFF button to turn off the appliance. B Press and hold "Program" (P) button and press ON/

OFF button to turn appliance ON.

B Record lowest operating gas pressure reading in

table 11.

Gas pressures lower than 3.5" W.C. for Natural Gas or 8" W.C. for LPG will result in insufficient degree rise to the hot water being used, reduced hot water volume, possible error code faults and must be corrected. See Gas Connections, chapter 3.8, page 17.

Fig. 32 Gas pressure test port (left tapping)

Fig. 31

B As soon as '188' is displayed, release "Program"

, button and the display should read P2.

B Press or until P1 appears.

Note: While in this mode the appliance will run constantly at maximum power and allow maximum water flow.

For inlet gas pressure adjustment consider the following table:

Gas type NG LPG

Static Gas Pressure Reading (see Chapter 3.12)

enter here: ___________________ Date: ___________

Operating Gas Pressure Reading (see Chapter 3.12)

enter here: ___________________ Date: ___________

Table 11

HIGH ALTITUDE OPERATION (see chapter 6.4 page 28, for details)

Altitude above sea level

0 - 2,000 ft (0 - 610 m)

2,000 ft - 4,500 ft (610 m - 1,372 m)

Above 4,500 ft (above 1,372 m)

Natural

Gas:

modification

adjustment with flue

gas analyzer required See

6.4 for instructions.

section

Liquid

Propane:

modification

Not approved

For operation at

elevations

above 2,000 ft

(610 m) the

equipment

ratings shall be

reduced at the

rate of 4% for each 1,000 ft

(305 m) above

sea level

3.5” WC 8” WC

Table 10 Minimum inlet gas pressure under full operation

B Turn on high volume of hot water flow (at least 6

gpm) and heater will ignite. If heater display reverts to P2, open more hot water fixtures to allow sufficient flow. Press until P1 reappears on display.

B Operate all other gas appliances on the same gas

piping system at maximum output.

Table 12

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4 Electrical connections

Electrical connections

4.1 Electrical power supply

Warning: For safety reasons,

disconnect the power supply cord to the heater before any service or testing is performed.

Warning: This heater must be electrically grounded in accordance with the most recent edition of the National Electrical Code. NFPA 70. In Canada, all electrical wiring to the heater should be in accordance with local codes and the Canadian Electrical Code, CSA C22.1 Part 1. Do not rely on the gas or water piping to ground the metal parts of the heater.

The GWH 2400 ES requires an electrical power supply from a 120VAC / 60Hz circuit (with a dedicated outlet) and must be properly grounded. The heater is wired as shown in the wiring diagram (chapter 9, Fig. 58).

4.2 Position of the fuses in control unit

To check fuses, proceed as follows:

B Remove the front cover, see Fig. 4, page 6. B Remove the three screws on front of the control unit.

Fig. 34

B Pull control unit free to access and remove the six

screws from the back cover of the control unit, see Fig. 35, pos. 2.

B Check the fuses in the printed circuit board, see Fig.

35, pos. 3.

Fig. 33 Connecting power supply cord

1 Power cord length: 3ft.

Note: Outlet appliance is plugged in to should be clear from possible water damage.

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6720608158-78.1AL

Fig. 35 Location of fuses

B After verifying the fuses mount all parts in reverse

order.

Operation instructions

5 Operation instructions

Fig. 36

1 On/Off button 2 Reset button 3 Program Key 4 LCD display 5 Up button 6 Down button 7 LED - Power On indicator or Stand-by

5.1 LCD Display functions

Warning: Do not use any cleaning or

corrosive agent to clean the window.

Fig. 37 Power bar indicator

Fig. 40 Lock indicator

Fig. 41 Flame indicator

Fig. 42 Remote control

Fig. 38 Temperature indicator

Fig. 39 Error indicator

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Operation instructions

5.2 For your safety read before operating your 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 main burner. When turning the heater on, follow these instructions exactly. B. Before operating the unit, press the On/Off button.

WHAT TO DO IF YOU SMELL GAS

B Do not try to light any appliance. B Do not touch any electric switch; do not use any

phone in your building.

B Immediately call your gas supplier from a neighbors

phone. Follow the gas supplier’s instructions.

B If you cannot reach your gas supplier, call the fire

department.

C. Use only your hand to press the on/off control switch. Never use tools. Follow these instructions exactly. If control switch 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.

5.4 Temperature selection

To select output water temperature:

B Press buttons or in order to reach desired

temperature.

Fig. 44

Setting the water temperature

The desired temperature of the hot water can be adjusted on the front control panel of the heater. The GWH 2400 ES has an electronically controlled gas valve that modulates the burner input in response to both varying hot water flow rates and/or changes in any incoming and outgoing water temperatures.

Note: The water heater, running at minimum BTU, may still achieve temperatures above the desired set temperature. Low flowing fixtures are the leading cause of this type of temperature overshoot. To combat this symptom, clean fixtures or replace with higher flowing ones.

Saving water resources:

5.3 Power

B To start the appliance press the On/Off button.

Fig. 43

Off

B To shut down the appliance press the On/Off button

again.

B Make sure you close all the taps after any use. Avoid

leaving the taps dripping. Repair any leaking tap.

B Define the temperature you want, in the appliance or

with the remote control. This way you have the precise water flow needed (mixing cold water to regulate temperature will increase the water flow with consequent waste of water).

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Operation instructions

5.5 Use of optional remote control accessory (part no. TSTAT2)

Fig. 48 Reset button

If the problem persists, contact your installer.

5.8 Program button

Fig. 45 Remote control

The wireless remote control accessory (Fig. 70, component 13) and the temperature selector buttons on the front of the water heater operate identically. Contact your distributor to order the remote control accessory. Modification of the water heaters interior control unit (Fig. 70, component 16) is required when programming the remote control with this heater.

NOTE: up to 6 remote controls can be programmed for one single water heater,

each with a range distance of 98 ft (30 m).

5.6 Operation

B When a hot water tap is opened, main burner ignites

and LCD displays the symbol .

Fig. 46

B LCD blinks until selected temperature is reached.

Program button can be used on the appliance and in the remote control.

Programming “Program” function

Programming actions are similar for both controls (appliance control pad and wireless remote control).

Fig. 49 “Program” key

Memorizing selected temperature

B Press buttons or to select temperature to be

memorized.

B Hold “Program” button for 3 seconds to save

temperature.

When LCD stops blinking, temperature is saved in memory.

Using “Program” function

In order to select memorized temperature

5.7 Reset button

If the LCD shows the error symbol do not shut off power or unplug the heater. See the error code on LCD and consult “Troubleshooting” section.

Fig. 47

After following instructions indicated in “Troubleshooting” section.

B press reset button to return heater to normal

operation.

B Press “Program” key.

LCD shows pre-memorized temperature, which is now the hot water selected temperature.

5.9 Locked condition

This condition is only valid for appliances with remote controls.

Fig. 50 Locked condition

Whenever LCD shows the temperature setting cannot be adjusted because the appliance is in use by a user which already selected a different temperature. Appliance will be automatically unlocked five minutes after closing the hot water tap.

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6 Maintenance and service

Maintenance and service

Warning: Always turn off the electrical

power supply, turn off the manual gas shut off valve and turn off the water shut off valves whenever servicing.

Caution:

B Check and clean the complete water

heating system once a year.

B Carry out a maintenance overhaul if

necessary. Immediately repair defects to avoid damage to the system.

Annual maintenance table

Every year

1. Inspect venting system X

2. Inspect heat exchanger X

3. Inspect burner X

4. Inspect condensate trap X

5. Inspect water filter X

Table 13 Annual maintenance

The unit should be checked once a year by a gas technician. If repairs are needed, the repairs should be done by a gas technician.

6.1 Annual maintenance

(To remove front cover, see page 6.)

Venting System

• Venting system - inspect inside of flue pipe for any blockage or restriction. Observe burner flames during heater operation. (Vent pipe must be removed). Inspect the combustion air inlet pipe for blockage or debris. Inspect combustion air and exhaust terminations for blockage or debris.

Combustion chamber

• Inspect burner observation window (Fig. 63, #10) for cracks or spillage of flue gases. Observe burner flames during heater operation. Flames should be steady and blue with no signs of yellowing. Yellow burner flames are an indication of improper combustion. Refer to Section 3.4 & 3.3 of this manual to ensure that exhaust system and combustion air supply meets manufacturer's specifications.

Inlet water filter

• Verify the inlet filter screen is clean and undamaged. The inlet water filter is located inside the cold water inlet fitting on the right side of the appliance (See Fig. 51, page 27). Close installer supplied cold water shutoff and loosen slotted screw on inlet fitting. Water will drain from the appliance. Remove cylindrical filter inside.

Fig. 51 Water filter

1 Inlet water filter 2 Water filter

Descaling

• In areas where the water supply has a high mineral content (see Table 9, page 20), the heat exchanger should be periodically flushed with a descaling solution. Scale build up will shorten the life of the water heater and damage resulting from is not covered under warranty. Refer to section 6.3 for detailed instructions on descaling the heat exchanger.

Heat exchanger fin coils

• Inspect heat exchanger fincoil for soot build-up or blockage. To access fincoil, venting must be removed from flue gas exhaust accessory. With venting removed and inspect fincoil below with a flashlight. If there is evidence of soot build-up or blockage, the heat exchanger should be removed by a professsional and cleaned thoroughly. To remove the heat exchanger, consult service bulletin at www.boschhotwater.com

6.2 Winterizing for seasonal use

Installation instructions state that the water heater must not be installed in a location where it may be exposed to freezing temperatures. If the heater must be left in a space which is likely to experience freezing temperatures, all water must be drained from the heater. If precautions are not taken, resulting damage will not be covered under the warranty. NOTE: Use of agents

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Maintenance and service

such as anti-freeze is not permitted as they may cause damage to the water heater's internal components.

1. Press ON/OFF switch on the water heater to turn OFF the heater and unplug power supply cord. The display should be blank.

2. Shut off gas supply to heater.

3. Shut off the water supply to the water heater using installer supplied shutoff valve.

4. Open hot water taps to drain the plumbing system. If water continues to flow after 5 minutes, a plumbing crossover is present and must be corrected before proceeding.

5. Open service valves (if available) or disconnect inlet and outlet water pipes from the water heater. Place a small bucket underneath the water heater to catch residual water remaining inside the water heater.

6. Using an air compressor, blow short bursts of air (100psi max) through the outlet water connection until there is no water present coming through the inlet water connection of the heater.

7. Reconnect water fittings and return heater to service when danger of freezing has past.

11.Make sure there are no leaks and the solution is flowing from the descaling reservoir through the heater and returning to the reservoir.

12.Run solution through the heater until the solution returning to the descaling reservoir comes out clear. (Changing to a fresh solution may be necessary during this process).

13.Disconnect all lines and drain all solution from heat exchanger. Properly discard of solution.

14.Position a container below the hot water outlet and connect cold water supply. Open cold water supply isolation valve and flush heat exchanger with clean water.

15.Shut cold water shutoff valve and reconnect hot water supply to the water heater.

16.Reconnect electrical supply to unit, open water shutoff valves, and return the unit to service.

6.3 Mineral scale build-up

Periodic descaling may be necessary in areas with high mineral content in the water. Scale buildup in the heat exchanger may result in lower flow rates, error codes of A7 and E9 and boiling sounds (knocking and banging) in the heat exchanger.

Descaling using a pump

1. Disconnect electrical supply from the water heater.

2. Shut off the water supply to the water heater using (installer supplied) shutoff valve.

3. Open hot water taps to drain and relieve pressure from the plumbing system.

4. Drain water from the unit's heat exchanger by disconnecting inlet and outlet water connections from the heater.

5. Connect a line (A) from the outlet of the circulating pump (installer supplied) to the inlet water fitting on the water heater (see Fig. 52).

6. Using another line (B), connect to the water outlet fitting on the water heater. Route the other end of this line into a descaling reservoir.

7. Using a 3rd line (C) from the descaling reservoir, connect to the inlet side of circulating pump. Install a filter on the end of this line in the descaling reservoir.

8. Make sure all connections are "water tight.".

9. Fill tank with descaling solution so both lines inside are submersed. We recommend straight white vinegar. If using a commercial descalant, refer to manufacturer's instructions on dilution with water.

10.Operate the circulating pump.

Fig. 52

6.4 Adjusting CO2 (carbon dioxide)

The CO2 can only be adjusted by a certified gas technician with a calibrated CO

Caution: One factor that may affect

levels is improper gas pressure.

Please see Chapter 3.12 for the procedure to measure gas pressure and record your findings below:

Static Gas Pressure: “ WC

P1 Operating Pressure: “ WC

The P1 minimum operating gas pressure is 3.5" WC for Natural Gas and 8" WC for Propane. Do not proceed in

analyzer.

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Maintenance and service

adjusting CO

until pressure is at or above these levels,

but not to exceed 10.5” WC for Natural Gas and 13” WC for Propane.

A. Once Gas Pressure is adequate

B Press ON/OFF button to turn off the heater. B Remove brass flat head screw on the exhaust collar

as seen in Fig. 53.

B Insert CO

analyzer probe into the measuring port.

The tip of the probe should be in the center of the flue pipe (approx 1.5" inserted). Avoid air gaps between probe and measuring port as they can alter readings.

Fig. 53 Measuring port

B While holding the Program (P) button in, press the

ON/OFF button to turn ON the heater (see Fig. 54). As soon as ‘188’ flashes on the display, release the Program button. The display should now read P2. Press button until “P1” appears on display.

Fig. 54

B Record the CO P2 CO

Reading: % CO

P1 CO2 Reading: % CO

reading in P1 and P2 below.

C. Adjusting CO2: Note: P1 adjustment will change the P2 reading.

Confirm the P1 value BEFORE adjusting the P2 level.

1. If P1 CO

level is off:

B Loosen yellow painted philips screw (1) and cover

should rotate down (2) revealing a recessed brass slotted screw. Fig. 55.

B Turning the slotted screw counter clockwise will

raise P1 CO CO

levels. Adjustments to the slotted screw will

also change P2 CO

B After bringing the P1 CO

levels and clockwise will lower P1

levels.

readings in proper range,

press the button to enter the P2 mode. Verify CO

readings in P2 mode.

2. If P2 CO

level is off:

B Remove yellow painted #40 Torx cover from the front

of the gas valve. (Fig. 56) A plastic #40 Torx screw will be revealed.

B Turning the plastic #40 Torx screw counter

clockwise will lower P2 CO will raise P2 CO

levels.

levels and clockwise

Note: This screw adjustment is very sensitive and should be made in small increments. It may take several minutes for readings to stabilize.

3. Verify both P1 and P2 CO

readings are within the

ranges specified in table 14. Repeat steps 1 and 2 as necesssary until CO

values are within the specified

ranges.

4. Once CO

values are within the specified ranges,

verify the CO readings on P1 and P2 do not exceed values shown in table 14. If values exceed this limit, inspect vent system and fin coils (chapter 6.1, page 27) for blockage.

B. Measuring CO

(combustion cover must be

installed):

B Open all hot water taps to achieve a flow rate of at

least 6 gallons per minute. (1 tub and 2 sinks should be sufficient). If heater display reverts to P2, open more hot water fixtures to allow sufficient flow. Press ‘ ’ until P1 reappears on the display.

B Record the CO

reading in P1 below. (Analyzer

reading may take several minutes to stabilize).

B Press the ‘ ’ button until P2 appears. Unit will

ramp down to low fire and the flow should decrease.

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D. Returning to Service:

1. Return slotted screw cover to original position and tighten philips screw.

2. Reinstall Torx cover.

3. Remove CO

analyzer probe and reinstall flathead

screw with gasket in exhaust collar.

4. Press ON/OFF button to turn OFF the heater and then turn ON the heater.

5. Heater is ready for normal operation.

Maintenance and service

CO2 range (%)

level

(measured)

Nat. Gas

max. input P1 6.9 % - 7.5 % < 250 ppm

min. input P2 2.3 % - 2.6 % < 60 ppm

LP Gas

max. input P1 8.1 % - 8.7 % < 250 ppm

min. input P2 2.5 % - 2.8 % < 60 ppm

* Values above are for climate controlled conditions. Inputs such as gas pressure, heating value of the gas, humidity and temperature of combustion air all impact CO

Max. CO

and CO

values. Changes in these inputs can result in

different CO and CO2 values on the same appliance.

Table 14 CO2 & CO target numbers

Final Readings

P2 CO

P1 CO2 Reading: % CO

Reading: % CO

Fig. 55 Adjusting P1 CO2 level

Fig. 56 Adjusting P2 CO

level

6720608158-38.1AL

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Maintenance and service

6.5 Program values

This section describes details on programming the appliance. For most applications the factory default values will robust and stable operation. Only adjust the factory settings if the installation requires changes as indicated in the appropriate section of this manual.

Program Description Factory Default MIN MAX Comment

P1 Maximum Power NG:40, LP:37 21 NG:40, LP:37 see chapter 3.12, page 22.

P2 Minimum Power 6 6 20 see chapter 6.7, page 33

P3 Remote Con-

trols installed

P4 Access to Diag-

nostic Mode

P6 Temperature

Unit

_0 _0 6 see chapter 5.5, page 26

E 0d 10f see chapter 6.6, page 32

°F °F °C

Refer to chapter 6.6 Control board diagnostics (page

32) regarding how to access these P-modes.

Caution: Misadjusted program values can lead to appliance malfunction, errors, and service calls.

note: reducing P1 values below maximum will reduce maximum power of the appliance.

Table 15 Program values, factory default settings and ranges.

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Maintenance and service

6.6 Control board diagnostics

1. Turn on/off switch on water heater to off (O) position.

2. Press and hold the program ( ) button while turning the on/off switch to the on (I) position. The display will cycle through a startup procedure including the software version.

3. Release the ' ' button when '188' appears on the display. The display should read 'P2' when the program button is released. If not, repeat process.

4. Press and release the ' ' button on the control panel until the display reads 'P4'. You are now in the diagnostic mode of the control board.

5. When the display reads 'P4', press and release the ' ' button once again and the display should read 'E'.

6. Use the ' ' and ' ' button on the control board to cycle through different diagnostic modes available.

7. Once in the selected diagnostic mode of your choice, press and release the ' ' button to display the diagnostic information.

EXAMPLE: to read the flow rate in gallons per minute while the unit is flowing water, cycle to the '3d' mode and press the ' ' button. A reading of 25 on the display would indicate the heater is reading a flow rate of 2.5 gallons/minute.

8. Once the information is obtained, press the ' ' button again to return to the diagnostic mode menu and scroll to addition diagnostic information.

9. To exit the diagnostic mode of the heater, use the ' ' or ' ' button until the display reads 'E'.

10.Press the ' ' button once again and the display should read P4.

11.Turn the on/off switch off (O) and back on (I) again to return heater to normal function.

Diagnostic menu

E Entry/Exit into sub-modes

0d Set-point temperature (°F)

1d Inlet water temperature (°F)

2d Outlet water temperature ( °F)

3d Water flow (gallons/min)

4d Gas type (LP or NG)

5d Fan speed (Hz)

6d Burner power (%)

7d Maximum power (kW)

8d Back flow temperature ( °C)

9d Flue gas temperature ( °F)

1F Most recent error/failure

2F 2nd most recent error

3F 3rd most recent error

4F 4th most recent error

5F 5th most recent error

6F 6th most recent error

7F 7th most recent error

8F 8th most recent error

9F 9th most recent error

10F 10th most recent error

Table 16

1) Available only on model GWH C800 ES

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Maintenance and service

6.7 Fan speed adjustment

Installation adjustment: Flue pipe length setting for minimum power - P2.

After installing the GWH 2400 ES, the minimum power fan speed must be selected to compensate for variation in vent pipe length.

Total vent length calculation

B Determine the total length of all straight sections of

vent pipe and enter in table 17, line 1.

B Count the number of 90° elbows used and enter that

value in line 2. (Do not count end terminal and first elbow after the appliance).

B Count the number of 45° elbows used and enter that

value in line 3.

B Repeat steps 1 through 3 for air intake pipe and enter

those values in the intake section of table 17.

B Add line 4 from Exhaust to line 4 of Intake and enter

result in line 5. This is the total equivalent vent length.

Exhaust

Straight section length __ x 1 = ____

90° elbows (qty) __ x 2.5 = ____

Example

Exhaust

Straight section length (feet)

90° elbows (qty) 1 x 2.5 = 2.5

45° elbows (qty) 0 x 1.25 = 0

Total: 24.5

Intake

Straight section length (feet)

90° elbows (qty) 1 x 2.5 = 2.5

45° elbows (qty) 0 x 1.25 = 0

Total: 17.5

Total equivalent vent length = 42

22 x 1 = 22

15 x 1 = 15

Table 18Determining vent length combination example

Note: Do not count 1st elbow and terminators

45° elbows (qty) __ x 1.25 = ____

4 Total:

____

Intake

Straight section length __ x 1 = ____

90° elbows (qty) __ x 2.5 = ____

45° elbows (qty) __ x 1.25 = ____

Total equivalent vent length = ____

Total: ____

Table 17Determining vent length combination (see

example in Table 18)

Example

Exhaust

• 7 - 3' straight sections

• 1 - 1' straight section Total length 22'

• 2 - 90° elbow.

Total maximum length not to exceed 52 ft.

Intake

• 5 - 3' straight sections

• 2 - 90° elbows.

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Total length 15'

Maintenance and service

To select fan speed:

B Press ON/OFF button into OFF. B Press and hold "Program" button and press

ON/OFF button to turn appliance ON.

Fig. 57

B As soon as '188' is displayed, release "Program"

button , and the display should read P2.

B Press or to choose the fan speed suitable

with your installation, see Table 19.

B Press and hold (± 5 sec.) “Program” button until

the display flashes, then the selected value is memorized.

Mode Pipe Length

Fan speed

for 3 ft up to 19 ft 6

“P2”

for 20 ft until 46 ft 7

for 47 ft until 52 ft 8

Table 19Fan speed adjustment

1) Full equivalent length (inlet+outlet+fittings). Do not count terminals and first elbow used on intake and exhaust.

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7Troubleshooting

Troubleshooting

Warning: If you are unable to perform

the tasks listed below, or need additional assistance please contact your original installer or licensed gas technician.

7.1 Introduction

Many of the questions customers ask regarding operation of this unit can be answered by following the troubleshooting steps as outlined below. Visit our web site at www.boschhotwater.com for more detailed troubleshooting and service bulletins. For best results, perform each step before proceeding to the next. The suggested solutions may require that the cover be taken off. (See Page 6. Fig. 3).

7.2 Burner do not ignite when hot water is turned ON

1. If the display is blank, verify power to outlet.

(120VAC/60Hz properly grounded circuit required). Verify that the heater ON/OFF button is turned ON.

2. Verify the fuses in the control board are good. See

Section 4.2, page 23 of the installation manual for fuse locations.

3. Make sure cold water inlet connection is plumbed to

the right side of heater when facing unit. See Fig. 28, page 20.

4. A minimum of 0.65 gallons per minute (GPM) (2.5 l/

m) is required to activate the heater. A quart container should fill in 25 seconds or less to activate heater. In areas of warm inlet water temperatures, the heater may increase activation rate to as high as 1.6 gallons per minute (GPM) to prevent overshooting of set temperature.

5. Clean inlet filter screen per chapter 6.2, page 27.

6. Inspect the water path for obstructions. Make sure all

showerheads, faucet aerators and whole house filters are clear of debris.

7. The heater activates when the water flow through the

unit is at or above the required minimum of 0.65 GPM (2.5 l/m). A crossover in the plumbing creates back pressure on the water flowing through the heater. Therefore, a higher flow rate than normal is needed to force the heater to activate. To check for a plumbing crossover, shut off the cold water supply to the water heater. Then open all of the hot water taps served by the heater. Wait 10 minutes and check for water flow at taps. There should be no water flowing. Any continuous flow of water, small or large, indicates a crossover is present and must be corrected. Consult a professional plumber for help in correcting a crossover. Failing single lever faucets

and mixing valves are common causes of plumbing crossovers.

8. With the ON/OFF switch turned to OFF (O) position and the power supply cord unplugged, remove the unit's front cover (See Page 6. Fig 3). Check wire connections between the water valve, control unit and electrode set. See chapter 12.1, page 46 for location of these parts.

7.3 Water is too hot

1. Selected temperature on the unit is set too high. To lower output temperature, see chapter 5.4, page 25.

2. Clean inlet filter screen per chapter 6.1, page 27.

3. Inspect the water path for obstructions. Make sure all showerheads, faucet aerators and whole house filters are clear of debris.

4. Confirm the heater's gas type coincides with the type of gas being supplied. See Fig. 2, page 5 for location of rating plate.

5. Avoid restrictive outlets. Clean all showerheads and faucet aerators. It may be necessary to upgrade to higher flow rate shower heads if allowable by local code.

6. In areas where the water has a high mineral content, periodic descaling may necessary. See chapter 6.3, page 28 for directions.

7. Ensure the outlet temperature sensor is making contact and firmly mounted on the hot water pipe.

7.4 Water is not hot enough

1. Selected temperature on the unit is too low. To raise output temperature, see chapter 5.4, page 25.

2. Clean inlet filter screen. See chapter 6.1, page 27.

3. Inspect the water path for obstructions. Make sure all showerheads, faucet aerators and whole house filters are clear of debris.

4. Confirm the heater's gas type coincides with the type of gas being supplied. See Fig. 2, page 5 for location of rating plate.

5. Check inlet gas particle screen for blockage at gas inlet connection on bottom of unit.

6. Verify gas pressure is in accordance with specifications in chapter 3.12, page 22. A gas pressure reading is needed to proceed further. Contact your original installer or a local certified gas technician to obtain this reading.

7. Cold water is mixing into the hot water lines (plumbing crossover). A plumbing crossover can unintentionally mix cold water with the hot water leaving the heater. The end result is a cooler water temperature than desired. To check for a plumbing crossover, shut off the cold water supply to the water heater. Then open all of the hot water taps served by

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Troubleshooting

the heater. Wait 10 minutes and check all taps for water flow. There should be no water flowing. Any continuous flow of water, small or large, indicates a crossover and must be corrected. Consult a professional plumber for help in correcting a crossover. Failing single lever faucets and mixing valves are common causes of plumbing crossovers.

8. Ensure the outlet temperature sensor is making contact and firmly mounted on the hot water pipe.

7.5 Low water flow/pressure

1. Too many hot water applications are being used simultaneously or too much flow is demanded. The water heater will effectively support two 2.0-2.5 GPM shower heads simultaneously or multiple sink applications. Greater draws will result in a water pressure drop and reduced flow at taps.

2. Ensure that gas pressure is in accordance with specifications in chapter 3.12, page 22. A gas pressure reading is needed to proceed further. Contact your original installer or a local certified gas technician to obtain this reading. If gas pressure is inadequate, the water heater will close its motorized water valve, reducing the hot water flow rate in an attempt to reach the selected output temperature.

3. If selected temperature on the unit is set too high for the demanded flow rate, the water heater will close its motorized water valve, reducing the hot water flow rate in an attempt to reach the selected output temperature. Lowering the selected temperature will allow the motorized water valve to open up for increased water flow rate.

4. Clean inlet filter screen per chapter 6.1, page 27.

5. Inspect the water path for obstructions. Make sure all showerheads, faucet aerators and whole house filters are clear of debris.

7.6 Hot water temperature fluctuates

at tap

1. Hot water is very hot out of the tap, requiring mixing of cold water in order to attain a useable hot water temperature. The addition of too much cold water will overpower the hot water flow from the tankless water heater. This slows the flow within the tankless water heater, decreasing it below activation point, which shuts off the burners. The end result is nothing but cold water coming out of the outlet. Consult www.boschhotwater.com for a detailed service bulletin on overcoming temperature fluctuations.

2. Unbalanced pressure in water lines. Any restriction in the water heater, such as a clogged inlet filter screen, can result in unequal pressures between the cold and hot water lines. In such cases, when mixing in the higher pressure cold water at the tap, the lower

pressure hot water can be overpowered. This will shut down the burners because the hot water flow rate fell below the minimum flow rate required for activation. Verify inlet filter screen is clean and clear of debris. See chapter 6.1, page 27 for inlet filter cleaning instructions.

3. Heater deactivated by temperature balancing valves. If the outlet water temperature is set too high, the heater can produce temperatures that are too hot. A temperature balance shower valve will automatically mix in cold water to reduce the hot water temperature. In the event of any temperature instability at a fixture using a temperature balancing valve, refer to the valve manufacturer for instructions on internal adjustment setting. An adjustment should be made to minimize the amount of cold water the valve is adding. Additionally, the temperature setting on the heater can be lowered to prevent the temperature balance valve from mixing in too much cold water.

4. Inlet water pressure is erratic due to fluctuating supply water pressure. For installation on a private well system with the use of a pressure tank, the lowest pressure range setting recommended is 4060 psi (2.75 - 4.15 bar). Consult your installer or local plumber for effective ways to maintain constant water pressure to the water heater when on a well system.

7.7 Noisy burner/heater during

operation

1. Sealed combustion leak. Make sure combustion cover is securely fastened. Ensure the exhaust vent adaptor is properly sealed with supplied gasket. Leaky seals create improper combustion resulting in noise.

2. Improper venting. Venting that is unsealed, the wrong material, too big in diameter or too long in run will result in unstable burner flames and noise. Ensure venting is proper and in accordance with specifications in chapter 3.3, page 8.

3. Lack of adequate combustion air. Drawing combustion air from a room area of inadequate size will result in unstable burner flames and noise. Improper use of piping for combustion air will result in unstable burner flames and noise. Ensure adequate combustion air is provided to the unit in accordance with specifications in Section 3.4, page 15, Combustion Air Requirements.

4. Cross contamination. Ensure that intake and exhaust terminations maintain minimum required clearances stated in the manual. Cross contamination between intake and exhaust may cause unstable burner flames and noise.

5. Lack of adequate gas pressure. Inadequate gas pressure will cause the fuel-to-air mixture (CO

) to be

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out of adjustment. This will result in unstable burner flames and noise. Ensure gas pressure is in accordance with specifications in section 3.12, page 22 Measuring Gas Pressure. A gas pressure reading is needed to proceed further. Contact your original installer or a local certified gas technician to obtain this reading.

6. Verify proper CO

28. CO

adjustments must be done by a certified

readings per chapter 6.4, page

gas technician with a calibrated combustion gas analyzer.

Troubleshooting

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Problem solving

8 Problem solving

8.1 Error code diagnostics

To remove error code from the display, press the reset button.

Display Cause Solution

Fault in the flue gas limiter. 1. Check continuity of the flue gas limiter (see Fig. 63, page 46).

Go to steps two and three to determine air box temperature sensor fault and replace it.

2. Check for flue gas leakage around the top and bottom seals of heat exchanger as well as the viewing window.

3. Check that venting is within specifications (see Section Long vent lengths, venting with more than three elbows, blocked vent or combination venting may cause this failure.

4. Check that flue gas limiter connector and spade connections are secure.

5. Unplug heater and check the two main plug connections inside the control board.

3.3).

Table 20

Jumper connection is not correct. 1. Check jumper connection on connector at upper right hand

Backflow temperature sensor defect

- happens if sensor is

disconnected or short circuit.

Outlet temperature sensor fault (Temperature below freezing or above 210°F).

* By installer or service technician only.

corner of heat exchanger.

1. Check backflow temperature sensor connection and resistance. See Fig. 61, page 44 and Fig. 63, page 46.

2. Replace backflow temperature sensor.

1. Check red wire connections at hot water temperature sensor. Clean terminals with an eraser. If badly corroded, replace sensor and wire harness. See Fig.

2. Sensor may trip if water temperature drops below freezing to protect heater from freezing conditions. Any damage due to freezing conditions is not covered under warranty.

3. Clean inlet filter screen and clear any debris out of shower heads, faucet aerators and whole house filters.

4. In areas where water has a high mineral content, periodic descaling may be necessary.

63, page 46.

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Display Cause Solution

Problem solving

(Flashing) Outlet temperature sensor not

sensing expected output temperature.

Primary fan rotation too low on operation.

No rotational speed sensor signal from primary fan.

1. Check that the sensor is firmly attached to the hot water pipe (see Fig. 69, page 52).

2. Clean inlet filter screen and clear any debris out of shower heads, faucet aerators and whole house filters.

3. Check venting specifications are met. Long vent lengths, venting with more than three elbows, blocked vent or combination venting may cause this failure.

4. Check gas pressure. Low gas pressure may prevent the heater from reaching desired output temperature.

5. Check supply voltage. It must be 120VAC and properly grounded.

6. Possible defective control unit call Bosch Water Heating for further instructions.

7. Ensure that outlet temperature sensor is not placed on any bends in the hot water pipe or misreading may occur.

1. Disconnect power supply cord and check wire connections on back side of primary fan and the two connectors on the control board (see Fig.

2. Check supply voltage. It must be 120VAC and properly grounded.

3. Check venting specifications are met. Long vent lengths, venting with more than three elbows, blocked vent or combination venting may cause this failure.

4. Ensure intake and exhaust terminations maintain the required minimum clearances stated in the manual. Cross contamination between intake and exhaust may cause the fan to alter its rotational speed.

5. Check gas pressure. Low gas pressure may cause the fan to change its speed to meet desired temperature.

6. Possible defective control unit call Bosch Water Heating for further instructions.

1. Disconnect power supply cord and check wire connections on back side of primary fan and the two connectors on the control board (see Fig.

2. Check supply voltage. It must be 120VAC and properly grounded.

3. Possible defective component in fan or defective control unit call Bosch Water Heating for further instructions.

70, page 53).

(Flashing) Water flow signal over specified

maximum value. Water flow > 10 gallon/min.

Internal hardware/software failure. 1. Disconnect power supply cord and check the two wire and

Table 20

* By installer or service technician only.

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1. Disconnect power supply cord and check wire connections on water valve and the two connectors on the control board (see

70, page 53).

Fig.

2. Excessive water pressure and flow. Ensure water pressure is less than 150psi and flow rate is below 10 gallons per minute.

ground connections on control board as well as ground connection on heater chassis.

2. Pushing the wrong combination of buttons on the control unit can create confusion among the microprocessors inside. In this case, the error code should not happen more than once or twice. Turn off the water heater. Turn water heater back on and try resetting error code. Use the reset button ( ) to reset any error codes.

3. Possible defective control unit. Call Bosch Water Heating for further instructions.

Problem solving

Display Cause Solution

Over-temperature detected by outlet temperature sensor on hot water pipe. Temperature > 185°F

Cold water temperature sensor fault.

Backflow temperature sensor over 309°F. The appliance will close the burner and lock.

1. Check that the sensor is firmly attached to the vertical section of the hot water pipe (see Fig. 69, page 52).

2. Check red wire connections at outlet temperature sensor. Clean terminals with an eraser. If badly corroded, replace sensor and wire harness. Check sensor resistance (see

3. Clean inlet filter screen per chapter debris out of shower heads, faucet aerators and whole house filters.

4. In areas where water has a high mineral content, periodic descaling may be necessary. See chapter directions.

1. Check connector on wires coming from top of watervalve for a secure connection. See Fig.

2. Sensor may trip if water temperature drops below freezing to protect heater from freezing conditions Any damage due to freezing conditions is not covered under warranty.

1. Check combustion air and backflow vent piping for blockage.

2. Check if secondary fan connections are disconnected.

3. Check venting specifications are met. Long vent lengths, venting with more than three elbows, blocked vent or combination venting may cause this failure.

4. Check sensor resistance (see

63, page 46.

6.2, page 27 and clear any

Fig. 61, page 44).

Fig. 59, page

6.3, page 27 for

Table 20

Overheat sensor (ECO) open circuit (should reset when cooler temperatures are detected).

* By installer or service technician only.

1. Disconnect power supply cord and check wire connections on overheat sensor (top right of heat exchanger) and the two connectors on the control board. See Fig.

2. Check white wire connections at overheat sensor. Clean terminals with an eraser. If badly corroded, replace sensor and wire harness.

3. Check venting specifications are met. Long vent lengths, venting with more than three elbows, blocked vent or combination venting may cause this failure.

4. Clean inlet filter screen and clear any debris out of shower heads, faucet aerators and whole house filters.

5. In areas where water has a high mineral content, periodic descaling may necessary, see

6. Unplug power supply cord to the water heater. Open a hot water tap for several minutes to allow cold water to pass through heat exchanger. Close hot water tap and disconnect lead wires to overheat sensor. Using a multimeter, check continuity through overheat sensor contacts. Replace sensor if open.

chapter 6.3.

63, page 46.

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Display Cause Solution

Problem solving

No flame ionization detected with water flow.

1. Verify that all manual gas shut off valves are open.

2. Check gas type, see Fig. 2, page 5.

3. Reset error code and open a water tap to cycle the heater in an effort to purge air on new installations. Cycling hot water tap on and off multiple times may be necessary. If heater still faults with EA error code, have a licensed gas technician properly purge air out of the gas line leading to the water heater.

4. Check three wire connections to ignition group on the lower front of the heat exchanger are secure.

5. Check gas pressure, see

6. Check venting specifications are met. Improper venting may cause premature failure of the flame sensor rod.

7. Check that the minimum power fan speed has been adjusted to

the proper value. See page 34.

8. Observe inside the viewing window of the heat exchanger when a hot water tap is opened. Sparking should be followed by a steady blue flame. If flame is unstable or yellow with proper gas pressure, confirm CO

Ionization failure during operation. 1. Check gas type, see

2. Check three wire connections to ignition group on the lower front of the heat exchanger are secure.

3. Check venting specifications are met. Improper venting may cause unstable burner flames and loss of flame ionization.

4. Check that the minimum power fan speed has been adjusted to

the proper value. See page

5. Check gas pressure, see section 3.12, page 22.

6. Check and adjust CO2 readings, see section 6.4, page 28.

chapter 3.12, page 22.

readings per section 6.4.

Fig. 2, page 5.

34.

Table 20

Ionization error at standby. 1. Loose connection to the flame ionization rod. Verify that the

Gas leakage error, gas valve circuit not closing properly.

* By installer or service technician only.

thinner wire leading from the control unit is securely connected to the flame sensor located on the lower front of the heat exchanger. See Fig.

2. Flame ionization rod or control unit may be damaged. Contact Bosch Water Heating for further instruction.

1. Disconnect power supply cord and check wire connections on gas valve and the two connectors on the control board.

2. Flow water out of a hot water tap above the minimum activation point of 0.65 GPM. Measure voltage at the gas valve wire plug connection. The voltage should measure 24VDC between the left pair of wires and 24VDC between the right pair of wires when the unit is operating. If voltage is not proper, contact Bosch Water Heating for further instruction.

3. Gas valve may be defective, contact Bosch Water Heating for further instrucation.

63, page 46.

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Electrical diagram

9 Electrical diagram

Fig. 58 Electrical scheme

1 Intlet water temperature sensor 2 Outlet water temperature sensor 3 Exhaust temperature sensor 4 Cascading output connection 5 Cascading input connection 6 Ionization sensor 7 Water flow sensor 8 Flue gas limiter 9 Heat Exchanger Overheat Sensor (ECO) 10 Gas valve 12 Water valve 13 Primary fan 14 ON/OFF switch 15 Secondary fan 16 AC plug 17 Main connection 18 Ignition electrodes 19 Ground post 20 Antifreeze Kit connection 21 Fuse 22 Fuse

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10 Sensor resistance charts

Outl et temperat ure s ensor c haracteristics

Sensor resistance charts

Fig. 59

222

217

212 207 202

19 7

19 2

18 7

18 2

177 172 16 7 16 2

157 152 14 7 14 2 13 7 13 2 12 7 12 2

117

Temp ºF

112 10 7 10 2

97 92 87 82

77 72 67 62

57 52 47 42 37 32

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

Re sist a nc e (Koh m )

110 10 5 10 0 95 90 85 80 75 70 65 60 55 50

Temp ºC

45 40 35 30 25 20 15 10 5 0

Inl et t em perat ur e sensor char act e ristics

247 242 237 232 227 222

217

212 207 202

19 7

19 2

18 7

18 2

177 172 16 7

16 2

157 152 14 7

14 2

13 7

13 2

12 7

Temp ºF

12 2

117 112 10 7

10 2

77 72 67

57 52 47

012345 6789101112131415161718192021222324

Re sist a nce (Koh m )

12 0 115 110 10 5 10 0 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0

Temp ºC

Fig. 60

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Sensor resistance charts

Back Flow characteristi cs

302 297 292 287 282 277 272 267 262 257 252 247 242 237 232 227 222 217 212 207 202 197 192 187 182 177 172 167 162 157

Temp ºF

152 147 142 137 132 127 122

117

112 107 102

97 92 87 82 77 72 67 62 57 52 47 42 37 32

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

Re sist a nc e (Koh m )

155 150 14 5 14 0 13 5 13 0 12 5 12 0 115 110 10 5 10 0 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0

Temp ºC

Fig. 61

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11 GWH 2400 ES Functional scheme

GWH 2400 ES Functional scheme

Fig. 62 Functional scheme

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Interior components diagram and parts list

12 Interior components diagram and parts list

12.1 Interior components

Fig. 63 Components

1 Flue gas collector 2 Heat exchanger 3 Flame sensor 4 Primary fan (Mixer) 5 Outlet temperature sensor 6 LCD display 7 On/Off button 8 Reset button 9 Program key 10 Flue gas limiter 11 Heat exchanger overheat sensor (ECO)

12 Ignition electrodes 13 Observation window 14 Backflow temperature sensor 15 Secondary air fan 16 Gas valve 17 Water valve with engine and temperature sensor 18 Control unit 19 Up button 20 Down button 21 LED

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Interior components diagram and parts list

Fig. 64 Appliance overview

6 720 608 782

Interior components diagram and parts list

12.2 Components diagram

12.2.1 Group 1

Fig. 65 Components Diagram

Item Description Reference

1 Front cover 8 705 431 286

2 Cover shield 8 705 506 862

3 Trade mark badge 8 701 103 140

4 Cover screw 8 703 401 170

5 Combustion cover 8 700 506 300

6 Combustion cover gasket 8 704 701 084

7 Observation window 8 705 600 003

8 Holding bracket 8 708 104 103

9 Screw 8 703 403 012

Table 21

6720902973.AA JF

Item Description Reference

10 Combustion cover clip 8 701 201 032

11 Grommet set 8 710 203 039

12 Exhaust accessory 8 705 504 162

13 Gasket exhaust 8 700 103 710

14 Inlet air cover 8 708 006 022

15 Inlet air gasket 8 700 103 166

16 Inlet air accessory 8 705 504 116

17 Mounting bracket 8 701 309 164

Table 21

6 720 608 782

12.2.2 Group 2

Interior components diagram and parts list

Fig. 66 Components Diagram

6720902974.AA JF

Item Description Reference

1 Heat exchanger 8 705 406 356

2 Heat exchanger top gasket 8 704 701 052

3 Flue gas collector 8 705 700 153

4 Overheat sensor (ECO) 8 707 206 204

5 Heat exchanger bottom gasket 8 704 701 054

Table 22

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Item Description Reference

6 Site window 8 701 000 401

7 Ignition group 8 701 302 249

8 Heat exchanger O-ring 8 700 205 147

9 Rubber grommet 8 710 303 027

Table 22

Interior components diagram and parts list

12.2.3 Group 3

Fig. 67 Components Diagram

Item Description Reference

1 Main burner 8 708 120 642

2 Burner gasket 8 704 701 087

3 Primary fan 8 707 204 071

4 Backflow temperature sensor 8 707 206 459

5 Washer 8 704 701 097

6 Fan mount nut 2 915 011 006

7 Secondary fan 8 707 204 072

8 Screw 8 703 403 012

9 Gas / Air Mixer 8 705 700 170

Table 23

6720902975.AA JF

Item Description Reference

10 Air duct O-ring 8 700 205 149

11 Venturi 8 700 306 226

12 O-ring 8 700 205 224

13 Mixer / Fan gasket 8 704 701 059

14 Screw 2 910 642 150

15 Plate gasket 8 701 004 049

16 Air supply duct 8 705 700 155

17 Screw 2 910 952 122

Table 23

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12.2.4 Group 4

Interior components diagram and parts list

Fig. 68 Components Diagram

Item Description Reference

1 Gas valve 8 707 021 019

2 Pressure tapping 8 703 404 219

3 Washer 8 700 203 041

4 Pressure balance tube 8 700 703 136

5 Pressure balance nut 8 703 300 041

6 Gas supply pipe 8 700 715 389

7 Gas valve washer 8 700 103 014

Table 24

6 720 608 782

6720608158-73.1AL

Item Description Reference

8 Gas filter 8 700 507 002

9 Gasket 8 704 701 085

10 Gas / Fan connector 8 705 202 140

11 Washer 8 704 701 062

12 Regulation screw 8 703 404 220

13 O-ring 8 700 205 009

14 Screw 2 910 149 181

Table 24

Interior components diagram and parts list

12.2.5 Group 5

Fig. 69 Components Diagram

Item Description Reference

1 Water valve with engine 8 708 505 024

2 O-ring 8 700 205 147

3 Cold water pipe 8 700 715 394

4 Pipe connection clip 8 701 201 028

5 Hot water pipe 8 700 715 392

6 Temperature sensor 8 700 400 015

7 Outlet fitting 8 703 305 349

8 Inlet / Outlet washer 8 710 103 045

9 Wireform spring 8 701 300 025

Table 25

Item Description Reference

10 Inlet fitting with filter 8 703 305 356

11 O-ring 8 700 205 157

12 Watervalve clip 8 716 102 607

13 Water filter 8 700 507 059

14 Washer 8 700 103 764

15 O-ring 8 700 205 231

Table 25

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12.2.6 Group 6

Interior components diagram and parts list

Fig. 70 Components Diagram

6720608782-08.1AL

Item Description Reference

1 Control unit 8 707 207 296

2 Fuse T2.5A 1 904 521 342

3 Fuse T1.6A 8 700 609 008

4 Power supply cables 8 704 401 371

5 Power supply cord 8 704 401 378

6 Fan cables 8 704 401 347

7 Wire harness 8 704 401 348

8 Jumper 8 704 401 376

Table 26

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Item Description Reference

9 Electrode cables 8 704 401 346

10 Flue gas limiter 8 700 400 032

11 Anti freeze kit 7 709 003 665

12 Remote control (optional) 8 707 207 153

13 Shaped seal (optional) 8 700 201 012

14 Screw (optional) 8 703 401 109

15 Printed circuit transceiver (optional) 8 708 300 123

Table 26

Protecting the environment

13 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.

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14 Limited Warranty

Limited Warranty

General

Aquastar water heaters are warranted by the Manufacturer (BOSCH) through Bosch thermotechnology corporation. Bosch thermotechnology corporation 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 Bosch thermotechnology corporation 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 twelve (12) years after the original installation and operation, Bosch thermotechnology corporation will furnish a replacement heat exchanger. However, if the water heater is in an approved domestic hot water recirculation application, this heat exchanger warranty is limited to five (5) years from date of original installation and operation. 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.

• 6. to damage resulting from scale deposits and/or highly mineralized / unsoftened water supply.

All Other Parts

If any other part fails within two (2) years after original installation and operation, Bosch thermotechnology corporation will furnish a replacement part free of charge.

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.

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 or distributor:

BOSCH THERMOTECHNOLOGY CORPORATION

Bosch Water Heating 340 Mad River Park Waitsfield, VT 05673 TEL. 800-642-3111

www.boschhotwater.com

In most cases, the dealer or distributor will be able to promptly honor your claim and subsequently notify Bosch thermotechnology corporation. However, all replacements are made subject to validation by Bosch thermotechnology corporation 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 Bosch thermotechnology corporation. It is expressly understood that the replacement warranty of Bosch thermotechnology corporation 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 Bosch thermotechnology corporation 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). Bosch thermotechnology corporation 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.

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Installer Checklist to be completed 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 _____________________________________________

Installer name _____________________________________________

Address _____________________________________________

Phone _____________________________________________

* See Chapter 3.12, page 22 and gas pressure table (to be filled out by installer)

Installation manual should be left with the owner after the installation is tested and completed

Replacement Parts available from:

BOSCH THERMOTECHNOLOGY CORPORATION

Bosch Water Heating 340 Mad River Park Waitsfield, VT 05673

Bosch Termotecnologia, S.A.

Estrada de Cacia

3801 - 856 Aveiro - PORTUGAL

TEL. 800-642-3111 www.boschhotwater.com

Bosch GWH 2400 ES NG, GWH 2400 ES LP User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual