Bosch 940ESO User manual

940 ESO

For Outdoor Installations Only

Temperature Modulated with Electronic Ignition

Suitable for heating potable water and space heating

(Intended for variable flow applications)

6720644956-00.1V

940 ESO - Natural Gas

940 ESO - Liquefied Petroleum (LP) Gas

6 720 644 956 (2010/09) US

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

vapors and liquids in the vicinity of this or any other

appliance.

Improper installation, adjustment, alteration,

service or maintenance can cause injury or

property damage. Refer to this manual. For

assistance or additional information consult a

qualified installer, service agency or the gas

supplier.

In the Commonwealth of Massachusetts this

product must be installed by a licensed plumber or

gas fitter.

Upon completion of the installation, these

instructions should be handed to the user of the

appliance for future reference.

What to do if you smell gas

• Close gas valve. Open windows.

• Do not try to light any appliance.

• Do not touch any electrical switch; do not use any

phone in your building.

• Immediately call your gas supplier from a neighbor’s

phone. Follow the gas supplier’s instructions.

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

department.

• Installation and service must be performed by a

qualified installer, service agency or the gas supplier.

6 720 644 956

Index

1 Warning 3

2 Appliance details 5

2.1 Features 5

2.2 Specifications (Technical data) 5

2.3 Unpacking the heater 6

2.4 General rules to follow for safe operation 7

2.5 Dimensions and Min. installation clearances 8

3 Installation requirements 9

3.1 Specialized tools 9

3.2 Introduction 9

3.3 Proper location for installing your heater 9

4 Installation using Outdoor Kit (BTOK) 10

4.1 Warnings 10

4.2 Installing outdoor vent cap on the appliance 10

4.3 Selecting heater location 12

4.4 Mounting instructions 13

5 Installation using the Recess

Box (7 736 500 043) 14

5.1 Heater placement and clearances 14

6 Installation instructions 17

6.1 Gas piping & connections 17

6.2 Water connections 20

6.3 Water quality 20

6.4 Domestic hot water recirculation 21

6.5 Space heating applications 22

6.6 Measuring gas pressure 24

7 Electrical connections 25

7.1 Electrical power supply 25

7.2 Position of the fuses in control unit 25

8 Operation instructions 26

8.1 Description of LCD display 26

8.2 For your safety read before operating

your water heater 27

8.3 Power 27

8.4 Temperature selection 27

8.5 Use of optional remote control accessory

(part no. TSTAT2) 28

8.6 Operation 28

8.7 Reset button 28

8.8 Fan speed 29

8.9 Program button 31

8.10 Locked condition 31

9 Maintenance and service 31

9.1 Annual maintenance 31

9.2 Winterizing for seasonal use 32

9.3 Mineral scale build-up 32

9.4 Adjusting CO2 33

9.5 Program values 35

9.6 Control board diagnostics 36

10 Troubleshooting 37

10.1 Introduction 37

10.2 Burner does not ignite when hot

water is turned ON 37

10.3 Water is too hot 37

10.4 Water is not hot enough 37

10.5 Low water flow/pressure 38

10.6 Hot water temperature fluctuates

or goes cold at tap 38

10.7 Noisy burner/heater during operation 38

11 Problem solving 39

11.1 Error code diagnostics 39

12 Electrical diagram 43

13 Sensor resistance charts 44

14 GWH 940 ESO Functional scheme 46

15 Interior components diagram

and parts list 47

15.1 Interior components 47

15.2 Components diagram 49

16 Protecting the environment 55

17 Limited Warranty 56

6 720 644 956

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 installation

location and proper combustion air

supply air supply 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.

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.

Warning: The appliance should be

located in an area where leakage of the

heater or connections will not result in

damage to the area adjacent to the

appliance. When such locations cannot

be avoided, it is recommended that a

suitable drain pan, adequately drained,

be installed under the appliance. The

pan must not restrict combustion air

flow.

Warning: The maximum inlet gas

pressure must not exceed the value

specified by the manufacturer and the

minimum value listed is for the purpose

of input adjustment.

Warning: If a water heater is installed in

a closed water supply system, such as

one having a backflow preventer in the

cold water supply line, means shall be

provided to control thermal expansion.

Contact the water supplier or local

plumbing inspector on how to control

this situation.

Warning: Keep appliance area clear

and free from combustible materials,

gasoline and other flammable vapors

and liquids.

Warning: Do not obstruct the flow of

combustion and ventilation air.

Warning: Precautions must be taken

prior to manually operating the relief

valve to avoid contact with hot water

coming out of the relief valve and to

prevent water damage.

Caution: Label all wires prior to

disconnection when servicing controls.

Wiring errors can result in improper and

dangerous operation.

Verify proper operation after servicing.

Warning: If a relief valve discharges

periodically, this may be due to thermal

expansion in a closed water supply

system. Contact the water supplier or

local plumbing inspector on how to

correct this situation. Do not plug the

relief valve.

Warning: If the water heater is used in

a space heating application, all piping

and components connected to the

water heater must be suitable for use

with potable water.

Warning: Toxic chemicals, such as

those used for boiler treatment, shall not

be introduced into the potable water

used for space heating.

6 720 644 956

Warning

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 opera-

tion.

Fig. 1

Warning: A water heater which will be

used to supply potable water shall not

be connected to any heating system or

component(s) previously used with a

nonpotable water heating appliance.

HOT

BURN

D A N G E R

Water temperature over 125°F can

cause severe burns instantly or

death from scalds.

Children, disabled and elderly are

at highest risk of being scalded.

See instruction manual before

setting temperature at water

heater.

Feel water before bathing or

showering.

6720608643-16.1AL

6 720 644 956

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

Accessories (Bosch part #)

• Optional wireless remote control accessory to

operate with the appliance (TSTAT2)

• Cascading kit (7709003962)

• External water filter (8703305356)

• Gas conversion kit (8719002176)

• Pipe Cover (PTPCES)

• Recess box (7736500043)

• Pressure relief valve (FWL-2).

2.2 Specifications (Technical data)

Approved in US/Canada

Capacity

Maximum flow rate: 7.15 GPM (27 l/min) at a 45°F

(25°C) rise.

Maximum output

160,500 Btu/h (47.0 kW)

Maximum input

199,000 Btu/h (58.3 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 6.6, page 24.

Water

• Hot water connection (inches) - ¾”

• Cold water connection (inches) - ¾”

• Water valve material: Polymer (PPS) (Polypropylene

Sulfid)

• Minimum water flow: 0.5 gallon/minute (1,9 l/m).

Note: Activation varies with inlet water temperatures

from 0.5 - 1.6 gallon/minute (1.9 - 6.1 l/m).

• Minimum recommended water pressure: 30 PSI

(2.07 bar).

• Minimum well pressure 40 psi, see page 20.

• Connections:

– Bottom of heater

Combustion

• NOx ≤40 Ng/J

(Nanograms of NOx (calculated as NO2) per

Joule of heat output).

• CO ≤250 ppm (measured)

• CO

level set from factory, see chapter 9.4, page 33.

1) The freeze prevention kit is designed to provide

protection for the water heater down to approximately

5°F for short term conditions only. It will not protect the

appliance in areas where the temperature is routinely

expected to be below freezing.

- The freeze prevention kit will not protect plumbing

outside the appliance from freezing. Precautions should

be taken.

BOSCH is constantly improving its

products, therefore specifications are

subject to change without prior notice.

6 720 644 956

Appliance details

Dimensions

• Depth (in): 11¼” (286 mm)

• Width (in): 17

” (452 mm)

• Height (in): 30½” (775 mm)

• Weight: 67 pounds (30.5 kg).

Gas types

Natural Gas.

LP Gas.

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)

• Over heat prevention (temperature limiter)

• Inlet temperature sensor

• Outlet temperature sensor

• Back flow temperature sensor.

Water protection

IP X4 (protection against water drops)

2.3 Unpacking the heater

In order for proper installation, this water heater

must be installed with the outdoor kit (BTOK)

accessory.

Before installing the unit, be certain you have the

correct heater for your type of Gas: Propane or

Natural Gas. Identification labels are found on

the shipping box, and on the rating plate which is

located on the right side panel of the cover.

Fig. 2 Rating plate

ASerial number

BType of gas

The box includes:

• 940 ESO

• Bracket for wall hanging the heater

• Installation manual (manual can be downloaded at

www.boschpro.com)

• Product registration card

• Energy Guide label (in the front cover).

Please complete and return the enclosed product

registration card.

The 940 ESO is not approved or designed for:

• Manufactured (mobile) homes, boats or any

mobile installation. (Modular homes are

acceptable for installation).

•Use above 8000 ft A.S.L. altitude (see page 29).

• Outdoor installation without installation of

Outdoor kit (BTOK) or Recess Box (7 736 500

043).

• Applications where inlet water temperature is

higher than 140ºF (60°C). A 3-way valve or

mixing valve must be installed before the

appliance if inlet water temperature exceeds

this limit.

If appliance is installed at elevations above

2000ft, refer to Section 8.8.1 Fan speed

adjustment.

6 720 644 956

Appliance details

To remove front cover

BLoosen the two Phillips head screws located on

bottom rear of cover (see Fig. 3).

Fig. 3 Loosen the two screws

BLift front cover panel upward and remove.

Fig. 4 Remove the front cover

To remove combustion cover (service only)

BOpen the four clips and remove the combustion

cover see Fig. 5.

Fig. 5 Remove the combustion cover

2.4 General rules to follow for safe

operation

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.

B2. Carefully plan where you install the heater. If not

installed correctly, fatal accidents can occur, such as

carbon monoxide poisoning or fire.

B3. The water heater must be installed outdoors using

the outdoor kit and/or recess box accessory.

B4. You must vent your heater so that the exhaust

gases discharge to the outdoors.

B5. The appliance and its gas connection must be leak

tested before placing the appliance in operation.

The appliance must be isolated from the gas supply

piping system by closing its individual manual gas

shutoff valve (not supplied with heater) during any

pressure testing at pressures in excess of ½ Psig (3.5

kPa).

B6. Keep water heater area clear and free from

combustibles and flammable liquids. Do not locate

the heater over any material which might burn.

B7. Correct gas pressure is critical for the proper

operation of this heater. Gas piping must be sized to

provide the required pressure at the maximum output

of the heater, while all the other gas appliances are in

operation. Check with your local gas supplier, and

see the section on connecting the gas supply, see

chapter 6.1

B8. Should overheating occur or the gas supply fail to

shut off, turn off the gas supply at the manual gas shut

off valve, on the gas line. Note: manual gas shutoff

valve is not supplied with the heater but must be field

installed.

B9. Do not use this appliance if any part has been

underwater. Immediately call a qualified service

technician to inspect the appliance and to replace any

part of the control system and any gas control which

has been underwater.

10. Failure to install heater correctly may lead to

unsafe operation and void the warranty.

6720644956-02.1V

6720644956-13.1V

6720644956-14.1V

6 720 644 956

Appliance details

2.5 Dimensions and Minimum installation clearances

Fig. 6 Dimensions

1On/Off button

2Reset button

3Program key

4Power ON or stand-by LED

5LCD display

6Up button

7Down button

6720644956-01.1V

5 ¼" 30 ½"

17 "

785 ¼"

11 ¼"

2 ¾"

6 ½"

2 "

5 ¼"

2 "

4 "

116

6 "

516

116

516

re s e t

6 720 644 956

Installation requirements

3 Installation requirements

3.1 Specialized tools

The following specialized tools may be required for

installation:

• Manometer

• Multi-meter

• Combustion Gas Analyzer.

3.2 Introduction

Please follow these instructions. Failure to follow

instructions may result in:

BDamage or injury.

BImproper operation.

BLoss of warranty.

If you are unable to perform the tasks required to install

this heater properly, please contact a locally licensed

plumber or gas technician.

3.3 Proper location for installing your

heater

Carefully select the location of the water heater. For

your safety and for proper heater operation, follow the

guidelines below:

B1. Locate the heater where gas and plumbing

connections are feasible and convenient.

B2. 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 9.2, page 32 “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.

6 720 644 956

Installation using Outdoor Kit (BTOK)

4 Installation using Outdoor Kit (BTOK)

4.1 Warnings

Outdoor kit (BTOK) includes:

• Supports (2) with screws

• Sealing gasket

• Control panel shield

• Outdoor vent cap.

4.2 Installing outdoor vent cap on the

appliance

Replace the control panel shield

BLoosen the two Phillips head screws located on

bottom rear of cover (see Fig. 3).

Fig. 7 Loosen the two screws

B1. Attach the supports (A) to the appliance by fasten-

ing with the four provided screws, as shown in Fig. 8.

Danger: The top of the outdoor kit will

get very hot during operation. Keep

away from children. Install heater in a

location where the top of the kit cannot

be reached by small children.

Danger: Flue gas will be released

through the outdoor kit. Flue gas is very

hot and contains carbon monoxide. The

outdoor kit cannot be installed on a

water heater mounted indoors. To

prevent risk of fire and carbon monoxide

poisoning, maintain all clearances

indicated in these instructions.

Danger: Do not place or store any

combustible material within 5 feet of the

appliance. Maintain specified clearance

to combustibles on the wall where the

appliance is installed and any adjacent

walls or overhang. Observe all

clearances required in this manual.

Danger: Surface temperature of the kit

is less than 140°F, except highest top

surface which may reach 300°F.

Warning: Do not mount water heater

directly onto vinyl siding, see Fig. 14.

Danger: the freeze prevention kit on

the appliance is designed to provide

protection from temperatures down to

approximately 5°F for short term

conditions only. It will not protect the

appliance in areas where the

temperature is routinely expected

to be below freezing. The freeze

prevention kit will not protect plumbing

outside the appliance from freezing.

Precautions must be taken:

BAlways drain the water heater if it will be

exposed to long term freezing condi-

tions.

Danger: the water in this appliance is

cold and always remains cold except for

the times when the burner is on. In the

event of power outage in conjunction

with freezing temperatures, it is

recommended that the heater be

drained.

Warning: Damage to the appliance

from freezing is not covered under the

manufacturer's warranty.

Warning: The control panel shield

must always remain closed, except

when making adjustments, to prevent

damage to heater from weather.

6720644956-02.1V

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