Bosch GWH 715 ES User Manual

GWH 715 ES

(GWH 715 CTDR EFS)

Temperature Modulated with Electronic Ignition Suitable for heating potable water only - Not approved for space heating purposes (Intended for variable flow applications)

GWH 715 ES - Natural Gas GWH 715 ES - 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 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.

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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.

• Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.

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

• Installation and service must be performed by a qualified installer, service agency or the gas supplier.

Index

1Warning 3

2 Appliance details 4

2.1 Features 4

2.2 GWH 715 ES Specifications (Technical data) 4

2.3 Unpacking the GWH 715 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 Proper location for installing your heater 8

3.4 Heater placement and clearances 8

3.5 Mounting installation 8

3.6 Gas piping & connections 10

3.7 Water connections 12

3.8 Water quality 12

3.9 Recirculation application 13

3.10 Combustion air requirements 13

3.11 Venting 15

3.12 Measuring gas pressure 24

6 Maintenance and service 29

6.1 Annual maintenance 29

6.2 Winterizing for seasonal use 29

6.3 Mineral scale build-up 30

6.4 Adjusting CO2 30

6.5 Program values 33

6.6 Control board diagnostics 34

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 25

4.1 Electrical power supply 25

4.2 Position of the fuses in control unit 25

5 Operation instructions 26

5.1 Description LCD display 26

5.2 For your safety read before operating your water heater 27

5.3 Power 27

5.4 Temperature selection 27

5.5 Use of optional remote control accessory (part no. TSTAT2) 28

5.6 Operation 28

5.7 Reset button 28

5.8 Program button 28

5.9 Locked condition 28

10 Sensor resistance charts 43

11 GWH 715 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 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.

Accessories (Bosch part #)

• Optional wireless remote control accessory to

operate with the appliance (TSTAT2)

• Cascading kit (TLINK)

•Outdoor kit (PTOK)

• External water filter (8703305356).

BOSCH is constantly improving its products, therefore specifications are

subject to change without prior notice.

2.2 GWH 715 ES Specifications (Technical data)

Approved in US/Canada

Capacity

Maximum flow rate: 7.3 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: 9” - 14” water column

• Natural Gas: 4” - 14” water column.

* To measure gas pressure, see Measuring Gas Pressure, chapter 3.12, page 24.

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 (2.5 - 6.1 l/m).

• Minimum recommended water pressure: 30 PSI

(2.07 bar).

• Minimum well pressure 40 psi, see page 12.

• Connections:

– Bottom of heater

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Appliance details

Combustion

•NOx ≤ 55 ppm

•CO ≤ 190 ppm

•CO

level set from factory, see chapter 6.4, page 30.

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)

2.3 Unpacking the GWH 715 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

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

• Back flow 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

24).

The box includes:

• GWH 715 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 gasket provided)

• Installation manual (manual can be downloaded at www.boschpro.com)

• Product registration card

• Energy Guide label.

Please complete and return the enclosed product registration card.

The GWH 715 ES is not approved or designed for:

• Manufactured (mobile) homes, boats or any mobile installation.

• Use above 4500ft A.S.L. altitude.

• Outdoor installation without installation of Outdoor kit (PTOK).

• 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.

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• Space heating purposes.

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 Remove the front cover

To remove combustion cover (service only)

B Open 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

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 the unit will be installed indoors and use indoor combustion air, the place where you install the heater must have enough ventilation. The National Fuel

Gas Code does not allow UNSEALED gas fired water heater installations in bathrooms, bedrooms or any occupied rooms normally kept closed. See chapter

page 13.

B 4. You must vent your heater. See

on VENTING.

B 5. The appliance and its gas connection must be leak

tested before placing the appliance in operation. The appliance must be isolated from the gas supply piping system by closing its individual manual gas shutoff valve (not supplied with 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

chapter 3.6.

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.

B 10. Failure to install heater correctly may lead to

unsafe operation and void the warranty.

3.11 (page 15). If

3.3, page 8 and 3.10,

chapter 3.11, page

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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 715 ES

TOP (A) 12”

FRONT (B) 1”

BACK 0”

SIDES 1”

FLOOR (C) 12”

VENT DIAMETER 3”

VENT CLEARANCES 1”

Table 1 Minimum clearances

Note: Vent clearances vary per manufacturer. Consult vent manufacturer for specific clearance information.

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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.

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.

3.3 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:

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.

3.4 Heater placement and clearances

The GWH 715 ES is approved for installation on a combustible wall (see chapter 3.5 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.

A. Top 12 inches (306 mm) B. Front 1 inches (25 mm) C. Back 0 inches D. Sides 1 inches (25 mm) E. Bottom 12 inches (306 mm)

Clearances from any exhaust vent pipe are dependent upon the clearance requirements of the stainless steel vent pipe manufacturer. Single wall stainless steel (AL29-4C) vent pipe (vent type rated for Category III appliances) must be used when exhaust venting this appliance. See chapter 3.11 (page 15) Venting.

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 29 “Winterizing” for draining instructions.

3.5 Mounting installation

Warning: before starting installation

B Check that there are no loose 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.

B Ensure that gas pipe, gas valve,

mixer, fans and burner have no damage and are properly fitted.

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.

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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. 8, page 9.

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. 9, page 9.

B Hang the appliance on the bracket, see Fig. 10, page

Installation instructions

Studs 16"

(406mm) on

center

Fig. 8 Distance between support boards

Fig. 10 Mounting the heater

Warning: Appliance must be installed vertically.

Fig. 9 Leveling the mounting bracket on the studs

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Installation instructions

3.6 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 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.

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.

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. 13, page 11 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 24 for the procedure to confirm gas pressure. Proper gas pressure must be confirmed at time of installation.

GAS CONNECTIONS

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

line.

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

any appliance connector is ¾”, see Fig. 13 for more details on pipe sizing.

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. 11.

Fig. 12

Gas piping

Inlet gas particle screen (included)

Minimum

3”

Fig. 11 Gas connection (drip leg)

Cap

Gas supply

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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 715 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 0.622132 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 EH

3/4 23 EH

1 30 EH

1 1/4 37 EH

10 20 30 40 50 60

82 58 47 41 37 34

161 116 96 83 75 68

330 231 188 162 144 131

639 456 374 325 292 267

* 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

1 1145 787 632 541 480 434 372 330 292 265 227

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

Black Iron Pipe Length of Pipe, Feet

Lengt h o f Flexible Corrugated Stainless Steel Tubing (CSST),

Tube size inches EHD*

10 20 30 40 50

1/2 18 EHD 129 91 74 64 58

3/4 23 EHD 254 183 151 131 118

1 30 EHD 521 365 297 256 227

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

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

ordinary number of fittings

Fig. 13

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Installation instructions

3.7 Water connections

Warning: This heater is not approved

for preheated water applications above 140°F (60°C). See chapter 3.9 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

Fig. 14

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. 16).

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).

3.8 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.

Fig. 15 Water filter

1 Water valve with engine 2 Water filter

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).

Description Max. Levels

pH pH 6.5 - 8.5

TDS (total Dissolved Solids)

Total hardness mg/l or ppm

mg/l or ppm 500

100

(6 grains)

Aluminum mg/l or ppm 2.0

Chlorides mg/l or ppm 250

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 2

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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. 16. 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.

3.9 Recirculation application

The GWH 715 ES Protankless water heater is approved for domestic hot water recirculation. 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 is also 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

715

Fig. 16 Plumbing Connections (with shutoff valves)

and Pressure Relief Valve

Warning:

In applications where inlet water temperature can exceed 140°F (60ºC), a 3-way valve or mixing valve must be installed before the appliance to prevent water exceeding 140°F (60°C) from entering the appliance.

Ariston Minitank

Fig. 17 Recirculation application

1 Full port isolation valve 2 Circulator (pump on timer) 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.

3.10 Combustion air requirements

Warning: In areas where outside temperatures commonly fall below 36°F, a twin pipe venting system is required. Failure to do so may result in

cold outside air being drawn in through the venting system due to a negative pressure in the house and across the heat exchanger coil causing it to freeze and burst. This failure is not covered under the manufacturer’s warranty.

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Installation instructions

Warning: When installed in an

environment where corrosive chemicals or dirty air are present the twin pipe system is required.

Twin pipe

The GWH 715 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 or semi rigid sealed 3” or 4” pipe. 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. 28 Letter I, page

21.

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: Terminations must prevent

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

Single pipe Note: This appliance requires 9950 cubic feet of

available combustion air, or a minimum of 1243 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 the outside (see twin pipe 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 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 vertical vent pipe 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:

• 1000Btu/hr if all air is taken from inside the building

• 2000Btu/hr if all air is taken from the outside by horizontal ducts

• 4000Btu/hr if all air is taken from the outside by direct openings or vertical ducts.

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:

• 3000Btu/hr if all air is taken from the outside by a direct opening or vertical duct.

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Installation instructions

3.11 Venting

Warning: Do not reduce the vent

(exhaust and combustion) pipe sizes and do not common vent with any other vented appliance or stove.

Warning: Failure to vent the exhaust gases to the outside with sealed stainless steel vent pipe (AL29-4C) may result in dangerous flue gases filling the structure in which it is installed.

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

Warning: Proper end terminal / rain cap must be used. Failure to do so may result in damage to the appliance.

This damage is not covered under the manufacturer's warranty.

Caution: The vent system must be

installed by a qualified installer in accordance with these instructions. If improperly installed, a hazardous condition such as explosion or carbon monoxide poisoning could result. Bosch Water Heating will not be responsible for improperly installed appliances.

3.11.1 Vent material and specifications

Establish vent clearances that comply with the vent manufacturer's specifications. In all cases, follow local codes. See Table 3.

The appliance should be located as close to the point of vent termination as possible. The maximum vent length is 26 feet (8 m) with one 90 degree elbow and approved terminator. Subtract 2.5 feet from the total vent length for each additional 90° elbow used (a maximum of three 90° elbows are permitted in the total vent length), or subtract 1.25 feet for every 45° elbow used. Horizontal sections of vent must pitch 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 other than the termination. 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 4 Terminator Part Numbers

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

Table 3 Venting Specifications

Note:

Maximum combination length for separate (twin) tubes:

• 52 ft + two 90° elbows + two terminals.

6 720 608 158

Material

Sealed single wall

stainless steel

(AL29-4C)

Sealed PVC or

any other rigid or

semi rigid pipe

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 5 Friction Loss Equivalent in piping and fittings

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

1) in all cases, follow local codes.

Installation instructions

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 6 Vent manufacturers

Minimum exhaust vent size and length

The minimum exhaust vent length is 3 feet (1 m) with one 90 degree elbow.

Fig. 18

Maximum exhaust vent and combustion air inlet lengths

page 35. See error code to confirm error, correct the problem and then reset the heater before operating.

3.11.2 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. 19 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 3, page 15.

Refer to chapter 3.11.3 for condensate drain requirements.

Note:

Maximum combination length for separate tubes:

• 52 ft + two 90° elbows + two terminals.

Vent Safety System

The GWH 715 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

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.

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Installation instructions

3.11.3 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 vent length is greater than 10 feet

• 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.

Warning: In areas where outside temperatures commonly fall below 36°F, a twin pipe venting system is required. Failure to do so may result in cold outside air being drawn across the heat exchanger coil causing it to freeze and burst. This failure is not covered under the manufacturer's warranty.

Fig. 22 Condensate drain installation

3" Venting Z-flex ProTech Heat Fab

90° Condensate Drain Tee

Horizontal Condensate Drain

2SVEVWCF03 FST3 &

FSDF3

2SVEDWCF03 FSHDT3 9321

93PPLSTEE

Fig. 23

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

Fig. 24

Condensate Drain Tube

2SVEDTK24 N/A 7000TUBE

Table 7 Approved Condensate Drain Part Numbers

6 720 608 158

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