Aquastar Inc Water Heater Gwh 1600 P Users Manual 6720608030 0605(GWH1600) 20 June

Bosch-aquastar-1600P.. Bosch-aquastar-1600P

gwh1600p 76809ab3-83d4-49fe-9295-2e9da472bdb1 AquaStar Water Heater GWH 1600 P User Guide |

2015-02-05

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MODEL GWH 1600 P

INDOOR MODEL

Standing pilot

Suitable for heating potable water only

Not approved for space heating or preheated water applications

MODEL GWH 1600 P NG - Natural Gas

MODEL GWH 1600 P LP - Liquefied Petroleum (LP) Gas

6 720 608 030 US (06.05) AL

Warning: If the information in this manual is not

followed exactly, a fire or explosion may result

causing property damage, personal injury or death.

Do not store or use gasoline or other flammable

vapor and liquids in the vicinity of this or any other

appliance.

Improper installation, adjustment, alteration, service

or maintenance can cause injury or property

damage. Refer to this manual. For assistance or

additional information consult a qualified installer,

service agency or the gas supplier.

In the Commonwealth of Massachusettes the

installation must be performed 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

•

Open windows

• Close gas valve.

• 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.

http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

6 720 608 030

Index

1 Warning 2

2 Appliance details 3

2.1 GWH 1600 P specifications (Technical data) 3

2.2 Unpacking the GWH 1600 P heater 4

2.3 General rules to follow for safe operation 4

2.4 Dimensions and installation clearances 5

3 Installation instructions 6

3.1 Introduction 6

3.2 Proper location for installing your heater 6

3.3 Heater placement and clearances 6

3.4 Mounting Heater 7

3.5 Combustion air requirements 8

3.6 Venting 9

3.7 Gas piping & connections 11

3.8 Measuring gas pressure 13

3.9 Water connections 13

3.10 Recirculation application 14

4 Operation instructions 14

4.1 For your safety read before operating your water heater 14

4.2 Lighting instructions 15

4.3 To turn off appliance 15

4.4 Setting the water temperature 15

4.5 Draining water from heater 16

5 Maintenance and service 17

5.1 Maintenance intervals 17

5.2 Water valve 17

5.3 Pilot 17

5.4 Main burners 18

5.5 Vent assembly 18

5.6 Mineral scale build-up 18

6 Troubleshooting 19

6.1 Introduction 19

6.2 Pilot does not light 19

6.3 Pilot lights, but goes out when button released 19

6.4 Pilot goes out during or after hot water use 19

6.5 Burners do not light with water flow 20

6.6 Hot water temperature fluctuates at tap 20

6.7 Water is too hot 21

6.8 Water is not hot enough 21

6.9 Burners ignite without hot water flow 21

6.10 Low hot water pressure 21

6.11 Noise when heater is running 21

6.12 Burners do not operate cleanly; yellow

flames when operating 22

7 Protecting the environment 23

8 Interior components and diagram parts list 24

8.1 Interior components 24

8.2 Components diagram 25

8.3 Parts list 26

9 Twelve Year Limited Warranty 27

1 Warning

Fig. 1

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.

Caution: Any changes or

modifications not expressly approved

by the party responsible for compliance

could void the user’s authority to

operate the equipment.

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Appliance details

2 Appliance details

2.1 GWH 1600 P specifications

(Technical data)

Approved in US/Canada

Capacity

GWH 1600 P: 4.3 GPM

Maximum output

GWH 1600 P: 91 525 Btu/hr

Maximum input

GWH 1600 P: 117 000 Btu/hr

Efficiency in %

Recovery efficiency 78%

Min. Output

GWH 1600 P: 23 906 Btu/hr

Gas Requirement

Gas connection (inches) - ¾” NPT

Inlet gas pressure under maximum operation*

• Propane: 10.5” - 14” water column

• Natural Gas: 5.7” - 14” water column.

* To measure Gas Pressure, see Measuring Gas

Pressure, chapter 3.8.

Venting

• Natural Draft

• Vent diameter (inches) - 5”

• Minimum height (feet) - 6’ with no elbows

• Vertical termination

• Sidewall termination only with AQ4 power vent kit.

Water

• Hot water connection (inches) - ½” NPT

• Cold water connection (inches) - ½” NPT

• Water valve material: Polymer (PPS) (Polypropylene

Sulfid)

• Minimum water flow: 0.5 gallon/minute (1.9 l/m)

• Minimum recommended water pressure: 30 PSI

(2.07 bar)

• Connections:

– Bottom of heater

Dimensions

• Depth (in): 8.66” (220 mm)

• Width (in): 18.11” (460 mm)

• Height (in): 25.79” (655 mm)

• Weight: 35 pounds (16 kg).

Gas types

Natural Gas.

LP Gas

Safety devices

• Flame failure device (ionization thermocouple)

• Pressure relief valve (supplied with heater)

• Over heat prevention (temperature limiter).

Water resistant

IP X4.

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Appliance details

2.2 Unpacking the GWH 1600 P heater

This heater is packed securely.

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:

• Pressure relief valve

• Mounting screws

• Product registration card

• Installation manual

• Incandescent particle tray.

Do not lose this manual, there is a charge for a

replacement.

Please complete and return the enclosed product

registration card.

The GWH 1600 P is not approved or designed for:

• Manufactured (mobile) homes, RV's or boats

• Heating or other recirculating/pumping applications*

• Solar/preheat backup or high temperature booster

use

• Installation in a bathroom.

* This includes domestic hot water circulator pump loop

systems that may be installed in home hot water system

prior to installing this unit. An approved recirculation

design can be found in chapter 3.10.

2.3 General rules to follow for safe

operation

•1. You should 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 should conform with

CGA B149.(1,2) INSTALLATION CODES and /or

local installation codes

•2. Carefully plan where you install the heater. Proper

clearances must be followed

•3. 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).

The appliance and its gas connection must be leak

tested before placing the appliance in operation.

•4. Keep water heater area clear and free from

combustibles and flammable liquids. Do not locate

the heater over any material which might burn.

•5. Correct gas pressure is critical for the optimum

operation of this heater. Gas piping must be sized to

provide the required pressure at the maximum output

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

operation. Check with your local gas supplier, and

see chapter 3.7 and 3.8 to verify proper gas line

sizing.

•6. 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

•7. 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.

BOSCH is constantly improving its

products, therefore specifications are

subject to change without prior notice.

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Appliance details

2.4 Dimensions and installation clearances

Fig. 3 Dimensions in Inches and (mm)

4Heat exchanger

5Burner

10 Temperature control

11 Water valve

20 Gas connection

26 Output control

36 Front cover

37 Hole for fixing to wall

38 Exhaust pipe to connector

39 Draft diverter with flue gas monitor

40 Gas valve

49 Observation window

102 Piezo

Fig. 4 Minimum clearances

Model GWH 1600

TOP (A) 12 inches (306 mm)

FRONT (B) 4 inches (100 mm)

BACK 0 inches

SIDES 4 inches (100 mm)

BOTTOM (C) 12 inches (306 mm)

Dimensions

inches (mm)

GWH 1600 P

A16.73” (425)

B25.75” (655)

C13.15” (334)

D5.11” (130)

E21.25” (540)

F2.55” (65)

G1.18” (30)

H3/4”

Table 1 Dimensions in inches (mm)

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Installation instructions

3 Installation instructions

3.1 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.

Please contact Bosch Water Heating with any

questions.

3.2 Proper location for installing your

heater

Carefully select the location of the water heater. For

your safety and for proper heater operation, you must

provide combustion air to the heater and a proper

exhaust vent system.

Follow the guidelines below:

B1. Locate the heater where venting, gas and

plumbing connections are feasible and convenient.

B2. The hot water lines should be kept short to save

energy. Centrally locating the water heater is best. It

is always best to have hot water lines insulated.

3.3 Heater placement and clearances

The GWH 1600 P is design certified for installation on

a combustible wall (see 3.4 Mounting installation)

provided the floor covering below the heater is

noncombustible. For installations in an alcove or closet,

maintain the minimum clearances to combustible and

non-combustible materials listed below. See also Fig. 4.

A. Top 12 inches (306 mm)

B. Front 4 inches (100 mm)

C. Back 0 inches

D. Sides 4 inches (100 mm)

E. Bottom 12 inches (306 mm)

Warning: The water in this water

heater is cold and always remains cold

except for the times that hot water is

being used. DO NOT INSTALL IN AN

AREA WHERE IT COULD FREEZE.

Drain the heater entirely if freezing

temperatures are anticipated in area

where heater is installed. See chapter

4.5 for draining instructions.

To prevent any freeze damage,

introduce short bursts of compressed

air (20-40psi) through these

connections to remove the residual

water in the horizontal pipes and water

valve.

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.

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.

Warning: Place the heater in a location

where water leaks will do NO DAMAGE

to adjacent areas.

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Installation instructions

3.4 Mounting Heater

Remove cover and inspect.

BRemove the temperature control.

BRemove the outer case by pulling it forwards and

then lifting upwards, see Fig. 6.

BEnsure that the flue terminal is clear.

BAfter inspection, replace front cover.

Install incandescent particle tray.

BInstall incandenscent particle tray using screws

provided as shown in Fig. 5.

Fig. 5 Incandescent particle tray illustration

Mounting heater.

The GWH 1600 P is design certified for mounting on a

wall.

The heater must be mounted on a wall using

appropriate anchoring materials. If wall is a stud wall

sheathed with plasterboard, it is recommended that

support board(s), either 1x4’s or 1/2" (minimum)

plywood first be attached across a pair of studs and

then the heater should be attached to the support

boards, see Fig. 7.

BSecure the two included L shaped hooks to wall

studs or support board 13 1/4” apart. (See Fig. 7).

BHang heater on two L shaped hooks. (See Fig. 8).

Fig. 6 Remove front cover

Fig. 7 Support board

Fig. 8 Secure heater to wall

Warning: before starting installation:

Bcheck that there are no loose parts

inside the appliance

Bensure that gas pipe, gas valve, and

burner have no damage and are

properly fitted.

BRead chapter 2.2 to verify proper gas

type and to check all parts are included

in box.

Front cover should be removed in order to

inspect components visually (see

instructions below).

Warning:

BDo not install this appliance on a

carpeted wall.

Incandescent particle tray

Screws

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Installation instructions

3.5 Combustion air requirements

The AquaStar water heater holds cold water in its

copper heat exchanger and water valve when not in use.

Because of this, any cold air that comes down through

the unit's vent pipe is capable of freezing these

components. 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 all the combustion appliances in

the area are not being supplied with a sufficient amount

of make-up air. A wood stove or furnace can rob the

makeup air in the AquaStar's vent pipe, leaving the cold

infiltrating air capable of freezing the cold water in the

AquaStar heat exchanger. More make up air is the

solution. Supplying more combustion air for all

combustion appliances is the solution. A HVAC

specialist should be used to design solutions for

providing more make-up air if necessary. Observe the

following instructions concerning combustion air.

Appliances located in unconfined spaces:

a) An unconfined space is one whose volume is greater

than 50 cubic feet per 1000 Btu per hour of the

combined rating of all appliances installed in the space.

That would be 5850 cubic feet for the AquaStar GWH

1600 P alone.

b) Installations in structures that have been tightly

constructed (air infiltration rate of 0.40 ACH or less)

must be provided for combustion air per the National

Fuel Gas Code. Consult a HVAC specialist if your air

infiltration rate is questionable.

Appliances located in confined spaces:

The confined space must be provided with 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.

Or the confined 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 400% if your louvers are wood and by

135% if your louvers are metal. Refer to the National

Fuel Gas Code for complete information. In buildings of

tight construction all air should be taken from outside.

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Installation instructions

3.6 Venting

BMinimum vent pipe diameter: 5 inches

BMinimum vertical vent height: 6 feet, with no elbows

BEstablish 12 inch rise before any elbow

The heater must be vented to the outside following all

local ordinances and specifications for installing a gas

appliance vent or chimney. The heater must be located

as close as practicable to a vertically rising chimney or

vent that has a listed vent cap at its termination point.

The venting system must be designed and constructed

so as to develop a positive flow adequate to remove flue

gasses to the outdoors. Consult the National Fuel Gas

Code if the vent will have elbows or share venting with

another natural draft appliance.

3.6.1 Horizontal venting

A power vent, with a proof-of-draft safety interlock

device, is required and is available for sidewall venting.

Contact your dealer. In the Commonwealth of

Massachusetts power vented applications must utilize

proof-of-draft safety interlock device.

3.6.2 Vertical venting

B A 5 inch diameter gas vent constructed of double

wall Type B gas vent is recommended. A 6 inch vent

is required in elevations greater than 2000 feet, see

Fig. 10. Under no circumstances should the vent

pipe be reduced in size.

B An approved gas vent connector must be attached

to the top of the water heater and rise vertically at

least 12" before entering into an approved gas vent

connector elbow.

B The minimum vertical gas vent height allowed is 6

feet; horizontal vent connectors and elbows are not

to be considered in the total gas vent height.

B All gas vent sections must be secured to each other

with sheet metal screws and be properly supported.

Horizontal runs:

Any gas vent section that is greater than 45 degrees

from the vertical is considered horizontal. Horizontal

sections must slope upwards at least ¼ inch for every

foot of its horizontal length and be properly supported.

Keep the horizontal section short and avoid too many

elbows. The maximum horizontal run allowed is half of

the total vertical vent height; horizontal vent connectors

and elbows are not to be considered in the total gas

vent height.

Vent termination:

The gas vent constructed of double wall Type B gas

vent must terminate above the roof surface with a listed

vent cap at a height that's in accordance with Fig. 11

and table 2, provided they are at least 8 feet (2.4 m)

from a vertical wall or similar obstruction. All other gas

vents that are not able to terminate within the minimum

specified height allowed must terminate not less than 2

feet (0.6 m) above the highest point where it's passed

through the roof and at least 2 feet (0.6 m) higher than

any vertical wall or similar obstruction within 10 feet (3.1

m).

Fig. 9 Flat roof

Fig. 10 Vent Adaptor for High Altitude Installations

Danger: Do not reduce the vent pipe

size. Do not put an elbow directly on top

of heater. Failure to follow venting

requirements may cause deadly exhaust

gases to enter living space.

Warning: Do not combination vent with

a mechanically vented appliance.

Warning: Horizontally venting to a

vertically constructed vent stack along

an outside wall of a building is not

permissible.

Warning: Horizontally venting to a

sidewall vent terminator (without power

vent) is not permissible.

LISTED VENT CAP

MINIMUM 6

FEET (1.8M)

LISTED GAS VENT

ESTABLISH A ONE

FOOT RISE BEFORE

ANY ELBOWS

5” X 6” ADAPTOR

USED ON HIGH

ALTITUDE

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Installation instructions

Masonry chimney

Masonry chimneys shall be built and installed in

accordance with NFPS 211 or local codes. A minimum

5" diameter gas vent pipe (metal double wall Type B),

or an approved clay flue liner or a listed chimney lining

system must be used when venting into a naturally

drafting, internal masonry chimney. 6 inch is required in

elevations greater than 2000 feet, see Fig. 10. Local

codes may require the use of both gas vent and an

approved lining system when venting into a masonry

chimney. The Commonwealth of Massachusetts

requires the use of a listed liner. Lining systems include

approved clay flue lining, a listed chimney lining system

or other approved material that will resist corrosion,

erosion, softening, or cracking from exhaust flue gases

at temperatures up to 1800 degrees F. The lining

system must be listed for use with naturally drafting,

draft hood equipped gas appliances. Follow local

codes and refer to NFGC 54 and NFPA 58.

Existing interior masonry chimney

The metal gas vent pipe should be permanently

mounted inside the masonry chimney. Double wall Type

B gas vent is recommended. The masonry chimney may

have to be tile or metal lined before the insertion of the

gas vent pipe; check local codes for clarification. The

lining material must be listed for use only with naturally

drafting, draft hood equipped gas appliances. Follow

manufactures instructions for installation of listed lining

material. You may not vent any other fuel burning

appliances into any free space remaining in the

chimney. The minimum vertical gas vent length within

the masonry chimney should be no less than 6 ft (1.8

m); the vent terminator should extend at least 3 feet (0.9

m) above where the chimney meets the roofline and at

least 2 feet (0.6 m) higher than any vertical wall or

similar obstruction within 10 feet (3.1 m). The top of the

gas vent should have an approved vent terminator. See

Fig. 12.

Fig. 11 Pitch roof

Fig. 12 Masonry chimney

GAS VENT TERMINATIONS FOR LISTED VENT CAPS

Roof pitch H (minimum) feet meters

Flat to 6/12 1.0 0.30

6/12 to 7/12 1.25 0.38

Over 7/12 to 8/12 1.5 0.46

Over 8/12 to 9/12 2.0 0.61

Over 9/12 to 10/12 2.5 0.76

Over 10/12 to 11/12 3.25 0.99

Over 11/12 to 12/12 4.0 1.22

Over 12/12 to 14/12 5.0 1.52

Over 14/12 to 16/12 6.0 1.83

Over 16/12 to 18/12 7.0 2.13

Over 18/12 to 20/12 7.5 2.27

Over 20/12 to 21/12 8.0 2.44

Table 2

LISTED VENT CAP

LOWEST DISCHARGE

OPENING

MINIMUM 6

FEET (1.8M)

ROOF

PITCH IS

X/12

LISTED GAS VENT

H (minimum) height

from roof to lowest

discharge opening

ESTABLISH A ONE

FOOT RISE BEFORE

ANY ELBOWS

GAS

VENT

LISTED

VENT CAP

VENT

CONNECTOR

Establish a

one foot

rise before

any elbows

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Installation instructions

3.7 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 should conform to CGA

B149 INSTALLATION CODES and/or local installation

codes.

Mount regulator to gas inlet pipe as shown in Fig. 13.

The arrow on the back of the regulator indicates the

direction of gas flow and should point toward the

appliance.

Fig. 13 Installation of Gas Pressure Regulator

Note: The GWH 1600 P comes with a gas pressure

regulator. Not installing or altering the gas pressure

regulator will be a violation of CSA certification of the

unit. The regulator supplied with the heater is preset for

the gas shown on the rating plate to the correct

pressure. It is an appliance level regulator designed for

(low inlet) pressure (less than 1/2 Psig or 14" W.C.).

GAS CONNECTIONS

BInstall a manual gas shut off valve, on the gas supply

line.

BInstall a union when connecting gas supply.

BAttach the appliance regulator to the inlet gas pipe.

BThe minimum diameter required for any appliance

connector used is ¾”.

BNational 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.

When 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.

HIGH ALTITUDE INSTALLATION

The pressure regulator provided with the heater is

adjusted to deliver the proper gas pressure (as

indicated on the rating plate and in the manual for

altitude up to 2000 feet (660 meters) above sea level.

On appliances being installed above 2000 ft (660

meters) elevation, the inlet gas pressure should be set

at installation to the value shown below.

Note: The gas pressures specified below refer to

pressures taken at the pressure tap on the gas inlet pipe

just above the regulator. See chapter 3.8 for measuring

gas pressure.

MAXIMUM INLET GAS FLOW PRESSURE SETTING

GAS LINE SIZING

The gas supply piping should be sized according to the

applicable code for a maximum draw of 117,000 BTUH.

Measure the length of gas supply line and use the tables

in Fig. 14 or the gas line manufacturer’s sizing tables to

determine the pipe diameter necessary to

accommodate the BTU demand of the unit. If there are

more gas appliances drawing on the same line, size the

gas line according to the total maximum amount of BTU

draw for all appliances.

Note: Under sizing the gas line may result in diminished

output and improper operation. See chapter 3.8 for the

procedure to confirm gas pressure.

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.

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.

Altitude Nat. Gas

inches W.C.

Liquid Propane

inches W.C.

0’ - 2 000 ft 5.7” 10.5”

2 000 ft - 4 500 ft 4.6” 8.4”

Table 3 Above 4.500 ft consult your local gas provider

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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.

Copper tubing is prohibited for use with Natural Gas in the Commonwealth of Massachusetts and not recommended

elsewhere.

Fig. 14

Follow boxed numbers for piping just one GWH 1600 P (example: ¾” B.I. Natural Gas pipe for 20 ft (6.1m). will

handle 190,000 btu’s (55.7 kWh). For multiple appliances combine the total btu input load and then refer to

applicable chart below.

* EHD = Equivalent Hydraulic Diameter. The greater the

value of EHD, the greater the gas capacity of the tubing

Maximum Capacity of Semi-Rigid copper 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

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.

Tube

size,

inches EHD*

10 20 30 40 50 60

1/2

18 EHD

82 58 47 41 37 34

3/4

23 EHD

161 116 96 83 75 68

30 EHD

330 231 188 162 144 131

1 1/4

37 EHD

639 456 374 325 292 267

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

30 EHD

521 365 297 256 227 207

1 1/4

37 EHD

971 661 528 449 397 359

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

Copper (LP gas only)

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 92 62 50 41 37 35 31 29 27 26

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

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

Nominal

Iron

Pipe Internal

Size Diameter

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

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

Length of Black Iron Pipe, Feet

N o m ina l

Iro n pipe

size

inc hes

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

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

Black Iron Pipe

Lenght of pipe, Feet

6 720 608 030

Installation instructions

3.8 Measuring gas pressure

Connecting manometer

BShut off gas.

BRemove front cover and locate inlet gas pressure

measuring point on the right side, see Fig. 15.

BLoosen screw from test point on the right side and

connect manometer tube on test point.

Fig. 15 Gas pressure measuring point

AInlet tap

Static pressure test

BTurn gas supply back on.

BRecord static gas pressure reading on back page of

manual.

Operating pressure test

BTurn on all hot water taps served by the water heater.

BSet flow control knob fully clockwise.

BSet slide control to the right.

BOperate all other gas appliances on same gas piping

system at maximum output.

BRecord operating gas pressure reading on back

page of manual.

Gas pressures lower than 5.7" W.C. for Natural Gas or

10.5" W.C. for LP Gas will result in insufficient degree

rise to the hot water being used, and must be corrected.

See Gas Line Sizing under chapter 3.7.

3.9 Water connections

When facing the heater, the ½” cold water inlet is on the

bottom right and the hot water outlet is on the bottom

left.

BInstall unions or the Webstone service valves

when connecting plumbing to the water

heater. This will facilitate any necessary

cleaning and servicing.

Although water piping throughout your structure may be

other than copper, we recommend that copper piping

or suitably rated stainless steel flex line piping be used

for at least three feet before and after the heater (follow

local codes if more stringent). Never sweat any rigid

piping directly to or beneath the water connections or

damage can occur to the internal water valve from

heating of the pipe. Plastics or other PEX type plumbing

line materials are not recommended for connecting

directly to the water heater. Keep water inlet and outlet

pipes to no less than ½" (12.7mm) diameter to allow the

full flow capacity.

It is recommended that all water piping below the heater

be properly insulated to avoid heat loss.

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.

Full port valves should be installed on both the cold

water supply and hot water outlet lines to facilitate

servicing the heater (see Fig. 16). For installation on a

private well system with the use of a pressure tank, the

lowest pressure range setting recommended is 30-50

psi (2.07 and 3.45bar).

Connecting the pressure relief valve (PRV)

The 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 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.

Fig. 16 Plumbing connections and pressure relief

valve shown with optional Webstone service

valves

6 720 608 030

Operation instructions

3.10 Recirculation application

Since recirculation through the heater is not

permissible, the following drawing is provided to outline

a proper recirculation application using the Aquastar

water heater with an Ariston minitank. This schematic is

for illustration only and must not be used for actual

installation without appropriate engineering and

technical advice from a professional properly licensed in

locality where the installation is made.

Fig. 17 Recirculation application

The use of a small electric mini-tank (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. A timed or

thermostatically controlled operation of the pump is

commonly done. The GWH 1600 P should be plumbed

in line before the mini-tank water heater. Contact Bosch

Water Heating if further instruction is needed.

4 Operation instructions

4.1 For your safety read before

operating your water heater

A. This appliance employs a piezo-igniter to light the

pilot burner. When lighting the pilot, follow these

instructions exactly.

B. What to do if you smell gas.

WHAT TO DO IF YOU SMELL GAS

BClose gas valve. Open windows

BDo not try to light any appliance.

BDo not touch any electric switch; do not use any

phone in your building.

BImmediately call your gas supplier from a neighbors

phone. Follow the gas supplier’s instructions.

BIf you cannot reach your gas supplier, call the fire

department.

C. Use only your hand to push in the gas control

buttons. Never use tools. If a button will not push in,

check to make sure the buttons are being pushed in the

proper sequence. Follow these instructions exactly. If

control button(s) are jammed, close the heater’s

individual manual shutoff valve and call a qualified

service technician. Forced or attempted 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.

Warning: If you do not follow these

instructions exactly, a fire or explosion

may result causing property damage,

personal injury or loss of life.

Note: Upon initial installation,

existence of air in the gas supply

line and in the water line may

cause some ignition delay. In that

case, repeat the ignition process

until all the air has been purged.

6 720 608 030

Operation instructions

4.2 Lighting instructions

BSTOP! Read the previous safety information.

BThe gas valve must be turned off by sliding the gas

valve button to all the way to the left.

Fig. 18

BWait five (5) minutes to clear out any gas. If you smell

gas, STOP! Follow “B” in chapter 4.1. If you don’t

smell gas, go to next step.

BThe pilot burner window is located in the front center

of the cover.

Slide the gas valve button to the position .

Fig. 19

BFully depress gas valve button.

Fig. 20

BWith the gas valve button fully depressed, light pilot

by pushing the piezo button. This step may have to

be repeated.

Fig. 21

BObserve the pilot flame through the peephole. The

gas valve button should be held down for at least 15

seconds with pilot burning before releasing. When

the gas valve button is released, the pilot should

continue to burn.

- If the gas valve button does not pop out when

released, stop and immediately call your service

technician or gas supplier.

- If pilot does not stay lit, repeat all steps.

- If pilot will not stay lit after several tries, slide the gas

valve button all the way to the left and call service

technician or gas supplier.

BThe heater will now fire at minimum power when

water is drawn at a rate greater than the required

activation flow rate.

Note: If main burner should fail to ignite, make sure pilot

is burning. If not, repeat lighting steps.

Note: The GWH 1600 P operates in two modes. See

SETTING THE WATER TEMPERATURE.

4.3 To turn off appliance

BSlide the gas valve button all the way to the left and

turn off the installer supplied manual gas shutoff on

the supply line to the heater.

Fig. 22

4.4 Setting the water temperature

The GWH 1600 P has a gas control that modulates

burner input in response to flow. Its purpose is to

6 720 608 030

Operation instructions

ensure that the hot water temperature will remain

steady, although the water flow demand might vary. The

output temperature can be adjusted with either the

temperature adjustment knob or the gas control slide.

Temperature adjustment knob

The temperature adjustment knob on the front bottom of

the heater (see Fig. 23) adjusts temperature by

adjusting flow capacity. See table 4 for details.

Fig. 23

As the temperature adjustment knob is turned counter-

clockwise, the output temperature will lower and the

activation rate will be raised. Turning the knob

clockwise will raise the temperature and lower the

activation rate.

Gas control slide button

The gas control slide button adjusts temperature by

adjusting how much gas is allowed to flow to the

burners.

As the slide is adjusted to the left, the output

temperature will lower, with the lowest setting being the

small flame position.

Fig. 24

The hottest position is the highest flame position all the

way to the right.

Fig. 25

4.5 Draining water from heater

If there is a risk of freezing, proceed as follows:

BRemove the retaining clip from threaded bushing

(pos. 1).

BRemove threaded bushing (pos. 2) from water valve.

BEmpty the appliance of all water.

Fig. 26 Drain plug and filter location

1Retaining clip

2Threaded bushing

Knob

position Clockwise Counter-

clockwise

Degree rise 90°F 45°F

Activation rate 0.5 GPM 1.1 GPM

Max flow rate 2.0 GPM 3.7 GPM

Table 4 Temperature rise (slide control to the right)

6 720 608 030

Maintenance and service

5 Maintenance and service

5.1 Maintenance intervals

The GWH 1600 P requires periodic maintenance. The

below time maintenance intervals should keep the unit

operating for many years.

Every year

BInspect inlet water filter screen ( 5.2)

BInspect pilot assembly and flame ( 5.3)

BInspect burner assembly ( 5.4)

Every 2 years

BLubricate and clean water valve ( 5.2)

Every 3 to 5 years

BRebuild water valve ( 5.2)

BClean pilot assembly and clean or replace orifice

( 5.3)

5.2 Water valve

The water valve is the main control that tells the heater

to fire. If the periodic maintenance is neglected, more

costly damage may occur over time.

Inspecting inlet water filter screen

Shut off the installer supplied cold water isolation valve

to the heater. If one is not installed, install before

proceeding. Open the nearest hot water tap to drain the

plumbing lines. Position a bucket under the heater's

water valve assembly to catch any water that may drain

from the heater. Remove the filter retaining clip located

at base of water valve (see Fig. 26). Remove the

threaded bushing to access the cylindrical filter inside.

Remove filter, clean with water and inspect for damage.

If the filter is at all damaged, it should be replaced.

Lubricating the water valve

A more detailed instruction is available on our website

at www.boschhotwater.com. Shut off the installer

supplied cold water isolation valve to the heater. If one

is not installed, install before proceeding. Open the

nearest hot water tap to drain the plumbing lines.

Position a bucket under the heater's water valve

assembly to catch any water that may drain from the

heater. Disconnect the inlet water pipe going to the

back of the water valve. Disconnect the water pipe

leading out of water valve to the heat exchanger. Do this

by removing the retaining clip on water valve assembly

and pulling the pipe free from the water valve. Loosen

the two set screws at the bottom of the water valve

where it connects to the gas valve. If the set screws are

seized, STOP and call Bosch tech support before

proceeding. Forcing and snapping seized set screws

may cause irrevocable damage to the water valve and

gas valve assemblies. Remove the water valve by

pulling it to the right. Separate the two halves of the

water valve by removing the five screws on the left side

of the water valve. Apply lithium or faucet & valve grease

to the pushrod and o-ring. (See Fig. 25, num. 23).

Inspect the venturi and clean if necessary. (see Fig 29,

num. 23).

Rebuilding the water valve

Several parts within the water valve should be replaced

every 3 to 5 years depending on water quality and

usage. The parts list and instructions can be found on

our website at www.boschhotwater.com. Failure to

rebuild the water valve can result in decreased

performance or damage to the heater.

5.3 Pilot

Inspecting pilot

The pilot should burn with a clean sharp blue flame. The

flame should fully engulf the tip of the thermocouple. If

it does not, clean the pilot assembly per procedure

below.

Cleaning pilot assembly

Shut off gas supply to the heater using installer supplied

manual gas shutoff. Locate pilot gas tubing mounted in

the center of the burner assembly. At the base of the

pilot gas tubing there is a retaining clip. Release pilot

gas tubing from this clip. Push upwards on other end of

pilot gas tubing to release it from burner mount.

Remove brass hex headed pilot orifice from gas valve

(located near base of pilot gas tubing). Soak orifice and

pilot gas tubing in carburetor cleaner for 30 minutes.

Dry off and reinsert orifice in gas valve. If heater is an LP

unit, replace orifice. Reinstall the pilot gas tubing

following removal instructions in reverse. Open gas

supply and return heater to service.

Warning: Failure to perform

recommended maintenance may result

in complete failure of the unit over time.

The warranty does not cover failures

due to improper or insufficient

maintenance.

Caution: Do not ream or poke orifice as

it will enlarge orifice opening.

6 720 608 030

Maintenance and service

5.4 Main burners

The main burner flames should be blue, with a more

intense blue cone in the center core. Yellow flames

could be a sign of wrong size gas orifices or dirty

burners, a blockage on the heat exchangers fins. If

some burners have yellow flames while others have blue

flames, it is likely that dust, lint or spider webs have

partially clogged the burner venturis. To clean the

burners, contact a gas service person.

5.5 Vent assembly

Inspect the draft hood and heat exchanger fins for signs

of soot build-up or any other foreign material such as

spider webs. Clean out any debris found in the vent

hood. Signs of soot indicate insufficient combustion air

or exhaust draft. Check for vent assembly blockage or

combustion air blockage on the underside of the unit.

5.6 Mineral scale build-up

The GWH 1600 P, when operated at lower

temperatures settings, does not accumulate mineral

build-up. If however, the heater is used at the higher

temperature settings and the water has a high mineral

content, periodic descaling may be necessary. The

heating coils should be flushed with a descaling

solution.

5.6.1 Descaling heat exchanger

1. Disconnect electrical supply from the water heater.

2. Shut off the water supply to the water heater using

(installer supplied) isolation 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

5. Connect the line (A) from the outlet of the circulating

pump (installer supplied) to the inlet water fitting on the

water heater

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. Verify

there is a filter on the end of the line in the descaling

reservoir.

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

9. Fill tank with descaling solution so lines inside are

submersed. We recommend a straight white vinegar

solution. If using a commercial descalant, refer to

manufacturer's instructions on dilution with water.

10. Operate the circulating pump.

11. Make sure there are no leaks and the solution is

flowing from the descaling reservoir through the heat

exchanger and returning to the reservoir.

12. Run solution through the heat exchanger 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 isolation valve and reconnect hot

water supply to the water heater.

16. Reconnect electrical supply to unit, open water

isolation valves, and return the unit to service.

Fig. 27

6 720 608 030

Troubleshooting

6 Troubleshooting

6.1 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. For best results, perform each step

before proceeding to the next. The suggested solutions

may require that the cover be taken off. (See chapter

3.4).

6.2 Pilot does not light

1. Verify gas supply is on at Natural Gas meter or

Propane Tank. Make sure all manual gas shut off valves

are in the open position. Have licensed gas technician

confirm adequate gas pressure at the inlet tap

(chapter 3.9). If gas is not present, verify manufacturer

supplied Maxitrol regulator is in the upright position. The

arrow on the back of the regulator should point in the

same direction as gas flow.

2. If the unit was just installed or the gas lines have been

worked on, there may be air in the gas line. Centered in

the sparking position, hold down the gas control slide

button while hitting the pilot igniter button every few

seconds. It may take several minutes to bleed air out of

the gas line.

3. Verify a spark is being thrown at pilot area while gas

control slide button, centered in the single flame

position, is being firmly depressed. Repeatedly push in

pilot igniter button to light the pilot. If no spark is

present, verify proper wire connection to the electrode.

4. Pilot assembly may be blocked. Clean or replace the

pilot orifice (chapter 5.3).

6.3 Pilot lights, but goes out when

button released

1. When lighting pilot ensure the gas control slide

button is fully depressed and held down for at least 20

seconds after pilot is lit.

2. Verify gas type indicated in rating sticker located on

right hand side of cover, coincides with the gas type you

are using. NG is a natural gas unit and LP is for liquid

propane.

3. If using a power vent, check the safety spillage switch

reset button (the safety spillage switch is wired through

the water heater's thermocouple circuit). The spill

switch should be located at top of water heater close to

draft diverter (Consult manual that came with

powervent).

4. Check all connections of the pilot safety circuit. The

pilot safety circuit consists of a thermocouple, overheat

sensor (ECO), flue gas sensor, safety spillage

switch(models with Powervents only) and the

electromagnet (See parts diagram for locations). Clean

sensor connections with light sandpaper if corrosion is

evident. The electromagnet connection is 5mm nut from

the thermocouple which screws into a larger 17mm nut.

Tighten both nuts snugly but do not over tighten.

5. Pilot flame should be blue in color and completely

engulfing the tip of the thermocouple. If not, have a

licensed gas technician verify gas pressure is in

accordance with manufacturer's specifications

(chapter 3.9) and clean or replace the pilot orifice

(chapter 5.3).

6. Have a licensed gas technician verify the proper

operation of the thermocouple by measuring the

millivoltage from the thermocouple lead to ground. The

proper reading should be 24mVDC or greater. If the

reading is lower, the thermocouple may be defective.

Call Bosch Water Heating for further instruction.

6.4 Pilot goes out during or after hot

water use

1. Pilot outage during use typically results from the

unit's safety overheat/high limit sensors interrupting the

pilot circuit. The GWH 1600 P does not have a

thermostat. If inlet water is preheated, the unit will

overheat, stopping the flow of gas. Plumb inlet with a

cold water line only.

2. Failure to vent properly by reducing pipe diameter,

improper use of elbows or not meeting required vent

length are common causes that deactivate the pilot

safety circuit. Confirm venting is in accordance with

manufacturer's specifications (see chapter 3.7).

3. Confirm the combustion air requirements are being

met in accordance with manufacturer's specifications

(see chapter 3.6). Proper venting and combustion air

will ensure a proper draft.

4. Confirm that the burners in the water heater go off

immediately when the hot water is turned off. If they

remain on or shut down slowly, then the overheat

sensor (ECO) will interrupt the pilot circuit and shut off

all gas to the heater. The water valve assembly, which

actuates the burners, may be dirty and require periodic

maintenance (every 2 - 5 years depending on water

quality and use) (see chapter 5.2).

5. Check all connections of the pilot safety circuit. The

pilot safety circuit consists of a thermocouple, overheat

sensor (ECO), flue gas sensor, safety spillage

switch(models with Powervents only) and the

electromagnet (See parts diagram for locations). Clean

sensor connections with light sandpaper if corrosion is

evident. The electromagnet connection is 5mm nut from

the thermocouple which screws into a larger 17mm nut.

Tighten both nuts snugly but do not over tighten.

6 720 608 030

Troubleshooting

6. Verify pilot flame completely engulfs the

thermocouple tip. If pilot is too small, clean pilot orifice

(see chapter 5.3).

7. If the water has a high mineral content, the heat

exchanger may be scaled internally. This restricts the

water path, causing the water to over heat which shuts

all gas off to the heater. Instructions for descaling the

heat exchanger are available at

www.boschhotwater.com.

8. If steps 1 through 7 do not correct the problem, then

confirm that the gas pressure is adequate. Ensure gas

pressure is in accordance with manufacturer's

specifications (see Chapter 3.9). A gas pressure

reading is needed to proceed further. Contact your

original installer or a licensed gas technician to obtain

this reading.

6.5 Burners do not light with water

flow

1. Verify the pilot is lit

2. Verify the gas control slide button is between the

1flame and 3 flame positions.

3. Verify the cold water supply is connected to the right

side of the heater.

4. Close installer supplied cold water shut off valve (if

none installed, install before proceeding). Open all hot

water taps supplied by the heater. Wait 5 minutes and

check all taps. Any water running is a sign of a plumbing

crossover. Consult a local plumber or service person for

help in correcting a plumbing crossover.

5. Verify flow through the water heater is sufficient. Turn

temperature adjustment knob all the way clockwise.

Fully open a hot water faucet and fill a quart container.

If the container fills in 30 seconds or less, the flow rate

(1/2 gallon per minute) is sufficient to activate the

heater.

6. Inspect the water path outside of the heater for

obstructions. Make sure all outlets (i.e. showerheads,

faucet aerators and whole house filters) are clear of

debris. Also, the water heater's inlet filter screen should

be inspected and cleaned (see chapter 5.2).

7. The water valve assembly, which actuates the

burners, requires periodic maintenance (every 2 - 5

years depending on water quality and use) (see

chapter 5.2).

6.6 Hot water temperature fluctuates

at tap

1. Close off installer supplied cold water shut off valve

(if none installed, install before proceeding). Open all

hot water taps supplied by the heater. Wait 5 minutes

and check all taps. Water running is a sign of a

plumbing cross-over. Consult a local plumber or service

person for help in correcting a plumbing crossover.

2. Check for a clogged inlet water filter screen (see

chapter 5.2).

3. Hot water is very hot out of the tap, requiring a lot of

cold water to be added with it in order to attain a

useable hot water temperature. The addition of too

much cold will overpower and slow 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.

Reduce the need for cold water mix by setting the gas

slide control button towards the single flame position

for lower hot water temperatures. If the problem

persists, go to www.boschhotwater.com for a more

detailed service bulletin on this problem.

4. The GWH 1600 P is designed to modulate gas flow

to the burners when water flow varies. If the water

pressure in the home is erratic and the water flow is not

consistent while a tap is opened, then the temperature

of hot water will fluctuate. The minimum water pressure

for the home should be 30psi or greater. For installation

on a private well system with the use of a pressure tank,

the lowest pressure range setting recommended is 30-

50 psi (2.07-3.45 bar). The use of a pressure reducing/

regulating valve before the water heater (directly after

pressure tank on well systems) is an effective way to

maintain constant water pressure to the water heater.

Watts brand 25AUB- ¾" or N35B-¾" pressure

reducing/regulating valves or equivalent are suggested.

5. If the inlet water temperature is not steady then the

hot water temperature from the water heater will

fluctuate. The GWH 1600 P modulates its burners

when the flow rate is changed; it does not have a

thermostat and will not adjust to changes in inlet water

temperature.

6. If the inlet water temperature to the water heater is

above 70°F, the heater may produce outlet

temperatures that are too hot for most users. A

temperature balance shower valve can automatically

mix in cold water to reduce such hot water temperature.

This can slow the flow within the tankless water heater,

decreasing it below activation point, which shuts off the

burners. In the event of any temperature instability with

the use of a temperature balance shower valve, refer to

shower valve manufacturer's instructions for internal

adjustment setting. An adjustment should be made to

minimize the amount of cold water the valve is adding.

7. The gas pressure also needs to be stable and

adequate. Ensure gas pressure is in accordance with

manufacturer's specifications (see chapter 3.9). A gas

pressure reading is needed to proceed further. Contact

your original installer or a local certified gas technician

to obtain this reading.

8. A water valve, which has not been serviced, may be

struggling to keep the gas valve open. The water valve

requires periodic maintenance (every 2-5 yrs

depending on water quality and use) (see chapter 5.2)

6 720 608 030

Troubleshooting

6.7 Water is too hot

1. Verify gas type indicated in rating sticker located on

right-hand side of cover, coincides with the gas type

you are using. NG is a natural gas unit and LP is for

liquid propane.

2. Adjust the gas control slide button from three flame

position towards the one flame position for cooler

temperatures. If the water is still too hot, the

temperature adjustment knob on the water heater

maybe set too high. Lower the setting and test water

temperature. This dial turns counter clockwise for lower

temperatures and clockwise for higher temperatures.

3. Inlet water is preheated. This model does not have a

thermostat and thus will not modulate flame height in

order to prevent over heating. It is designed for a cold

water feed only. Replumb the heater with cold water to

the inlet.

4. Increase the flow rate. Restrictions in the water path

can slow the flow of water through the heater, resulting

in very hot outlet temperatures. Restrictive

showerheads and faucet aerators should be cleaned

out or upgraded with less restrictive ones. In addition,

the water heater's inlet filter should be cleaned and

inspected (see chapter 5.2).

5. If water is still too hot, consult service bulletins on

www.boschhotwater.com to lower outlet temperatures

further.

6. If the water has a high mineral content, the heat

exchanger may be scaled internally. This restricts the

water path, causing the water to boil and produce

extremely hot temperatures. Instructions for descaling

the heat exchanger are available at

www.boschhotwater.com.

6.8 Water is not hot enough

1. Verify gas type indicated in rating sticker located on

right-hand side of cover, coincides with the gas type

you are using. NG is a natural gas unit and LP is for

liquid propane.

2. Flow at one particular tap is too great or too many

fixtures are running at one time. Lower flow to stay

within heater's specifications.

3. Ensure the gas control slide button is all the way to

the 3 flame position. In addition, the temperature

adjustment knob on water heater maybe set too low.

Turn the knob clockwise for higher temperatures and

test the water temperature.

4. Shut off installer supplied cold water shut off valve (if

none installed, install before proceeding). Open all hot

water taps supplied by the heater. Wait 5 minutes and

check all taps. Any water running is a sign of a plumbing

crossover. Consult a local plumber or service person for

help in correcting a plumbing crossover.

5. Inspect the water path outside of the heater for

obstructions. Make sure all outlets (i.e. showerheads,

faucet aerators and whole house filters) are clear of

debris. Also, the water heater's inlet filter screen should

be inspected and cleaned (see chapter 5.2).

6. The water valve may be dirty, prohibiting it from fully

opening the gas valve. This part needs to be periodically

serviced (every 2-5 yrs depending on water quality and

use) (see chapter 5.2).

7. Gas pressure is too low. Ensure gas pressure is in

accordance with manufacturer's specifications (see

chapter 3.9). A gas pressure reading is needed to

proceed further. Contact your original installer or a local

certified gas technician to obtain this reading.

6.9 Burners ignite without hot water

flow

1. The water valve may be dirty and sticking, prohibiting

it from fully closing the gas valve. This part needs to be

periodically serviced (every 2-5 yrs depending on water

quality and use) (see chapter 5.2).

6.10 Low hot water pressure

1. Confirm adequate flow rate through the unit. With

cold supply shut off to the unit, disconnect hot outlet

side to the unit. Place a half gallon jug under hot outlet

to catch water. Open cold supply and measure flow rate

out of the unit. With temperature adjustment knob set all

the way clockwise, the flow rate should be close to

2gpm, filling the jug in 15 seconds. With the

temperature adjustment knob set all the way

counterclockwise, the flow rate should be close to

4gpm, filling the jug in 7 seconds. If the flow rate is not

adequate, inspect and clean the inlet filter screen (see

chapter 5.2).

2. Confirm the incoming water pressure to the unit is

above the required 30psi.

3. Inspect the water path outside of the heater for

obstructions. Make sure all outlets (i.e. showerheads,

faucet aerators and whole house filters) are clear of

debris.

4. Be sure to run only one major application at a time

with this unit. Opening too many taps at one time can

disperse water flow resulting in a diminished flow/

pressure at all outlets.

5. If the water has a high mineral content, the heat

exchanger may be scaled internally. This restricts the

water path, causing diminished water flow. Instructions

for descaling the heat exchanger are available at

www.boschhotwater.com.

6.11 Noise when heater is running

1. Confirm adequate flow rate through the unit. With

cold supply shut off to the unit, disconnect hot outlet

side to the unit. Place a half gallon jug under hot outlet

to catch water. Open cold supply and measure flow rate

out of the unit. With temperature adjustment knob set all

6 720 608 030

Troubleshooting

the way clockwise, the flow rate should be close to

2gpm, filling the jug in 15 seconds. With the

temperature adjustment knob set all the way

counterclockwise, the flow rate should be close to

4gpm, filling the jug in 7 seconds. If the flow rate is not

adequate, inspect and clean the inlet filter screen (see

chapter 5.2).

2. Inspect the water path outside of the heater for

obstructions. Make sure all outlets (i.e. showerheads,

faucet aerators and whole house filters are clear of

debris. Restrictions in the water path can slow water

flow through the heat exchanger causing it to boil and

make noise.

3. If the water has a high mineral content, the heat

exchanger may be scaled internally. This restricts the

water path, causing the water to boil resulting in noise

and overheating. Instructions for descaling the heat

exchanger are available at www.boschhotwater.com.

6.12 Burners do not operate cleanly;

yellow flames when operating

1. Verify gas type indicated in rating sticker located on

right-hand side of cover, coincides with the gas type

you are using. NG is a natural gas unit and LP is for

liquid propane.

2. Gas pressure may be inadequate resulting in

improper combustion. Ensure gas pressure is in

accordance with manufacturer's specifications (see

chapter 3.6). A gas pressure reading is needed to

proceed further. Contact your original installer or a

licensed gas technician to obtain this reading.

3. For proper combustion at high elevations the inlet

gas pressure should be set at installation to the value

shown in table 3 (while operating at maximum BTU). A

gas pressure reading is needed to proceed further.

Contact your original installer or a licensed gas

technician to obtain this reading.

4. Ventilation is not adequate. Ensure adequate com-

bustion air is being supplied to the unit in accordance

with manufacturer's specifications (see chapter 3.6).

5. Make sure the water heater is vented properly. Check

for proper draft and ensure venting is in accordance

with manufacturer's specifications (see chapter 3.7).

6. The water heater has burners much like a furnace. It

is essential that they remain clean and are supplied with

adequate air for combustion. If the flames burn yellow or

orange, it is strongly recommended that the burners be

removed from the unit and cleaned. Once the burners

are removed, the fins in the top of the heat exchanger

can be accessed and brushed or vacuumed clean.

Instructions to remove burners are available at

www.boschhotwater.com.

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Protecting the environment

7 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.

Saving water resources:

BMake sure you close all the taps after any use. Avoid

leaving the taps dripping. Repair any leaking tap.

BSet the water heat to the temperature you want. This

way you have the precise water temperature needed

(mixing cold water to regulate temperature will

increase the water temperature with consequent

waste of water).

For increased safety shut off the appliance from

the main water supply if your are staying away

from home for a considerable time.

At below freezing temperatures, disconnect the

plumbing connections to the heater and allow

the heater to drain.

To prevent any freeze damage, introduce short

bursts of compressed air (20-40 psi) through

these connections to remove the residual water

in the horizontal pipes and water valve.

Follow instructions in chapter 4.5 to remove any

additional water remaining in the watervalve and

heat exchanger.

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Interior components and diagram parts list

8 Interior components and diagram parts list

8.1 Interior components

Fig. 28 Functional scheme

4Heat exchanger

5Burner

10 Temperature adjustment selector

11 Water valve

20 Gas connection

22 Flexible hot outlet

26 Gas control slide

30 Pilot gas tubing

102 Piezo

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Interior components and diagram parts list

8.2 Components diagram

Fig. 29 Components Diagram

25 17

21 23

35 13

36 37

6720608124-10.1 JF

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Interior components and diagram parts list

8.3 Parts list

Item Description Reference

1 Front cover 8 705 431 244 0

2 Shield 8 705 506 759 0

3 Temp. control knob 8 702 000 304 0

4 Draft Diverter 8 705 505 442 0

5 Exhaust pipe union Ø128 8 705 504 046 0

6 Angle bracket 8 708 003 192 0

7 Cover retaining clip (x10) 8 700 506 200 0

8 Heat exchanger 8 705 406 275 0

9 Cold water pipe 8 700 715 061 0

10 Main burner NG 8 708 120 618 0

10 Main burner LP 8 708 120 619 0

11 Connector 8 705 209 062 0

12 Piezo clip (x10) 8 701 201 019 0

13 Sparking plug 8 748 107 089 0

14 Pilot gas pipe 8 700 707 369 0

15 Tube (x10) 8 740 609 002 0

16 Pilot screen 8 700 507 067 0

17 Gas valve LP 8 707 021 401 0

17 Gas valve NG 8 707 021 279 0

18 Throttle housing 8 705 502 067 0

19 Washer (x10) 8 701 004 044 0

20 Pilot injector LP 8 708 200 326 0

20 Pilot injector NG 8 708 200 327 0

21 Pilot valve 8 708 500 301 0

22 Poppet valve head (5) LP 8 708 500 245 0

22 Poppet valve head (2) NG 8 708 500 358 0

23 Electromagnet 8 707 201 028 0

24 Sealing screw 8 703 305 283 0

25 Valve operation housing 8 708 008 069 0

26 Guide plate 8 701 000 387 0

27 Gas pressure regulator LP 8 707 406 083 0

27 Gas pressure regulator NG 8 707 406 084 0

28 Water valve 8 707 006 344 0

29 Watervalve pushrod (10x) 8 703 204 051 0

30 Diaphragm (L) 8 700 503 084 0

31 Inlet water connection 8 700 306 110 0

32 Selector screw 8 708 500 304 0

33 Piezo igniter 8 708 108 051 0

34 Fixing bracket 8 701 302 181 0

35 Ignition lead 8 704 401 040 0

36 Thermocouple 8 707 202 083 0

37 Flue gas safety device 8 707 206 445 0

38 Washer (x10) 8 701 004 043 0

39 Heat exchanger washer 8 700 103 658 0

40 Threaded bushing 8 700 306 148 0

41 Connector 8 700 306 187 0

42 Water filter 8 700 507 059 0

43 Outlet hose 8 700 703 139 0

44 Water connection clip 8 701 201 020 0

45 Plunger 8 703 502 039 0

46 Volumetric water governor 8 705 705 034 0

47 ECO 8 707 206 017 0

48 Temperature limiter 8 707 206 132 0

49 Venturi 8 708 205 279 0

50 Hot water pipe 8 700 715 178 0

51 Gas supply pipe 8 700 715 351 0

52 Cover 8 705 500 105 0

Table 5

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Twelve Year Limited Warranty

9 Twelve Year Limited Warranty

General

Aquastar water heaters are warranted by the

Manufacturer (BOSCH) through BBT North America.

BBT North America (BBTNA) 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 BBTNA

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 BBTNA will

furnish a replacement heat exchanger. However, 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.

All Other Parts

If any other part fails within two (2) years after original

installation and operation, BBTNA will furnish a

replacement part free of charge.

Shipping costs

In addition to supplying the replacement part(s),

BBTNA will provide ground service delivery for these

parts. Expedited or upgraded shipping will be charged

to the customer.

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.

How to Make a Claim

Any claim for warranty parts should be made to your

local dealer, distributor or to BBTNA. If BBTNA, please

contact the Technical Support Department:

BBT NORTH AMERICA

Bosch Group

340 Mad River Park

Waitsfield, VT 05673

Phone: 800-642-3111

www.boschhotwater.com

In most cases, the dealer or distributor will be able to

promptly honor your claim and subsequently notify

BBTNA. However, all replacements are made subject to

validation by BBTNA 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 BBTNA. It is expressly understood that the

replacement warranty of BBTNA 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 BBTNA 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). BBTNA 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.

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.

Installer Checklist, to be performed 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 __________

Average Winter Temperature __________

Average Summer Temperature __________

Installing Company _____________________________________________

Installer name _____________________________________________

Address _____________________________________________

Phone _____________________________________________

* See Chapter 3.8 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

VULCANO Termodomésticos S.A.

Estrada de Cacia

3801 - 856 Aveiro - PORTUGAL

BBT NORTH AMERICA

Bosch Group

Bosch Water Heating

340 Mad River Park

Waitsfield, VT 05673

Phone 800-642-3111

Fax 802-496-6924

www.boschhotwater.com

techsupport@boschhotwater.com

Aquastar Inc Water Heater Gwh 1600 P Users Manual 6720608030 0605(GWH1600) 20 June

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