Bosch WR430-3K Owner's manual

6 720 606 181 CA (03.11) AL
Model
WR430-3K
• installation
• operation
• maintenance
The Bosch instantaneous water heater is a high efficiency,
space saving answer to your water heating needs. All Bosch
instantaneous water heaters heat water only as required;
no energy is lost maintaining a large volume of water at
elevated temperatures as in tank-type storage water heaters.
Suita le for heating pota le water only. Not approved for
space heating purposes.
POWER VENTED - ELE TRONI IGNITION
ASTRAVAN DISTRIBUTORS, LTD.
123 Charles Street
North Vancouver, B.C. V7H 1S1
Phone Canada: [phone]
Phone USA: [phone]
We Site: www astravan.com
Note: In case of problems please contact your salesman or installer
NOTI E TO INSTALLER: Please leave this
manual with the owner or affix adjacent to
appliance.
Instantaneous gas water heater
WARNING: If the information in this
manual is not followed exactly, a fire or
explosion may result causing property
damge, personal injury or death.
- Do not store or use gasoline or other
flammable vapors and liquids in the vicinity of
this or any other applicance
- WHAT TO DO IF YOU SMELL GAS
• 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.
READ INSTRU TIONS AREFULLY BEFORE INSTALLING

2
Water Connection 1/2” Thread fitting
H x W x D 29 3/4” x 18 1/4” x 8 3/4”
Vent 4” (Category III Gas Appliance)
Max. lineal vent pipe length 15’ (4.5m)
Gas Connection 1/2” NPT thread
Shower pressure 40 Psi
Min. Water Pressure 18 Psi (no fittings attached)
Max. Water Pressure 150 Psi
Shipping Weight 50.6 LB
Net Weight 44 LB
2.5 GPM at 90° rise (32°C) (9.5 l)
5.0 GPM at 45° rise(16°C) (19.5 l)
Min. Water Flow 1/2 gal/min
120V/60Hz 1.2 Amps
LP GAS Supply Pressure inlet. min. 11”W.C.*
LP GAS regulator outlet pressure 9.9”W.C.*
Natural Gas Pressure inlet min.: 7”W.C.*
Natural Gas Regulator Pressure 5.38 W.C.**
* Inlet gas pressure must not exceed this value
** For purposes of input adjustment
ELECTRICAL 3 ft. ( 0.9 m) power ca le supplied c/w CSA
3 prong plug.
UNPA KING THE BOS H WR430-3K HEATER
This heater is packed securely. The ox includes two water connection fittings, a control kno , a gas pressure regulator, a
pressure relief valve, an incandescent particle tray, two hooks for hanging the heater, this manual. Do not lose this manual
as there is a charge for replacement.
BOS H WR430-3K
Principle of Operation:
When a hot water faucet is opened, the flow of water through
the heater causes the gas valve to open. At the same time
a microswitch is activated which sends a spark to the pilot.
The flame sensor confirms that the pilot has een lighted
and allows urners to ignite. The pilot goes out. The power
exhaust system runs as long as the urners are on. The
heat exchanger coils a sor the heat generated y the
urners and transfer heat to the water. When the hot water
faucet is shut off, the gas valve automatically closes and
the urners turn off, followed immediately y the exhaust
system. Your hot water faucet is an ignition key to turn on
the water heater, giving you control over your hot water energy
use. Every time you turn off your hot water faucet, the energy
consumption for hot water returns to zero.
FEATURES
- Power Venting with safety shutoff
- Electronic Pilot Ignition
- On/Off switch to activate system
- High Quality Materials for Long Working Life.
- Copper heating coils for endless supply of hot water.
- Burner output proportional to hot water flow demand for
maximum energy efficiency.
- Safety flame sensor at pilot urner.
- Automatic over heating protection shut-off sensor.
- Stainless steel urners with sta ilized lue flame.
- Built-in corrosion resistant power venter.
- Compact space saver: mounts on a wall with two hooks.
- Easily remova le one-piece cover.
- Easy one person installation.
- Adjusta le water flow restrictor ensure that water flow
demand will not exceed the heating capacity of the heater.
NAT. GAS PROPANE
max. 130 000 Btu/hr 125 000 Btu/hr
Gas Input min. 28 000 Btu/hr 28 000 Btu/hr

3
DIMENSIONS
Figure 1
Maximum Hydrostatic water pressure - 1.03 MPa (150 p.s.i.)
Maximum recommended working pressure - 0.69 MPa (100 p.s.i.)
Minimum working pressure - 0.09 MPa (13 p.s.i.) no piping attached
Reccomended pressure for showers and domestic, 0.27 MPa (40 p.s.i.)
• The high altitude ratings listed are Canadian Gas Association high altitude ratings and are valid only in Canada. In the U.S., the
National Fuel Gas Code, ANSI Z223.1-1988, recommends for high altitude installations a ove 2,000 feet, that the input rate e
reduced 4% for each 1,000 feet a ove sea level. - See page 14.
D084_089
EXTERIOR
TERMINATION
Model Type of Gas Altitude Input
Size, mm Qt.
1.20 diam. 18
WR430-3.K.. 0.79 diam. 18
1.20 diam. 18
0.79 diam. 18
Main Burner Orifices
natural gas
propane
0 - 2 000 ft 130 000 Btu/hr (38 kW)
2 - 4 500 ft 116 000 Btu/hr (34 kW)
0 - 2 000 ft 125 000 Btu/hr (36 kW)
2 - 4 500 ft 112 000 Btu/hr (33 kW)

4
FORWARD
The design of the WR430-3K complies with CAN 1-4.3
and ANSI Z21.10 (latest edition) as an instantaneous gas
water heater. In addition, the WR400-3K also complies with
CAN 1-2.17 for use at high altitudes, 2,000 - 4,500 ft. a ove
sea level.
Installation, operation and maintenance instructions are
provided in this manual. Installation and operation
instructions should e thoroughly reviewed efore
proceeding with installation of the BOSCH instantaneous
gas water heater.
Note: Proper plum ing, venting, gas connections and an
adequate supply of com ustion air are required for
safe and relia le operation. A ility equivalent to that
of a licensed tradesman in the field involved is
required for installation and/or service of these water
heaters.
LO ATION
Before installing the BOSCH instantaneous gas water
heater, consideration must e given to proper location. The
location should e as close to outside vent termination as
practica le, in an area with an adequate air supply and as
centralized with the piping system as possi le. The heater
should not e located in an area where it will e su ject to
freezing. The heater should e located in an area where
leakage of the heater or its connections will not result in
damage to the area adjacent to the heater or to lower floors
of the structure. See venting page 5.
Note: When such locations cannot e avoided, it is
recommended that a suita le drain pan, adequately
drained, e installed under the water heater. The pan
must not restrict com ustion air flow.
ELE TRI AL
A grounded switched plug recepta le must e provided
immediately elow the left hand corner of heater to accept
and provide power to supplied 3 ft. (0.9m) appliance ca le
and plug.
INSTALLATION INSTRU TIONS
The Bosch WR430-3K is a high efficiency fin tu e heater and should not e installed and operated during construction or
uilding renovations if location is exposed to a ove normal dust levels. This can cause dust uild up in the finned heat
exchanger and result in damage to heater and e a hazard to health.
The BOSCH instantaneous gas water heater is designed
to operate on natural or propane gas: however, make sure
that gas on which heater is to operate is the same as
specified on the heater’s model/rating plate.
In addition to these instructions, the water heater shall e
installed in accordance with CAN/CGA-B149 Installation
Code (in Canada) or Z223.1-latest edition, National Fuel
Gas Code (in U.S.A.) and/or local installation codes. These
shall e carefully followed in all cases.
AIR REQUIREMENTS
For safe operation, sufficient air for com ustion, ventilation
and dilution of flue gases must e availa le. An insufficient
supply of air will result in a yellow luminous urner flame,
causing car oning or sooting of the heat exchanger.
In order to prevent corrosion, make sure that the com ustion
air is kept free of aggressive su stances. Su stances that
especially contri ute to corrosion are halogenated
hydrocar ons (e.g., chlorine and fluorine) which are
contaned in solvents, paint, adhesives, propellant gases,
various household cleaners, etc. Take precautionary
measures as necessary.
In unconfined spaces, in uildings of normal construction,
infiltration normally is adequate to provide air for com ustion,
ventilation and dilution of flue gases. However, a confined
space must e provided with two permanent openings to
provide com ustion and ventilation air to the appliance. Each
opening shall have a free area of one square inch per 1,000
Btu/Hr* of total input rating of all the appliances in the
enclosure. One opening shall e within 12 inches of the
top and one within 12 inches of the ottom of the enclosure.
* Special Note
When the WR430-3K is installed in a confined space of
minimum size the openings descri ed a ove must e
increased in to a size of 1-1/2 square inches per 1,000
BTU/Hr. In other words, when installed in a minimum sized
confined space the two openings that are to e made in
the enclosure within 12 inches of the top and 12 inches of
the ottom must each have a minimum free area of, (1-1½”
- 2" x (130) = 195 square inches.

5
Expansion and contraction of piping due to changing water
temperature in the pipes imparts movement to the heater
which, if mounted directly to a rittle, fria le oard, such as
plaster oard, can cause failure of mounting.
For either a confined or unconfined space in a uilding of
tight construction with inadequate infiltration, air must e
drawn from the outdoors or from spaces that freely
communicate with the outdoors. Two permanent openings
located as indicated are to e provided as follows:
1. When communicating with outdoors directly or by
means of vertical ducts, each opening shall have a
free area of not less than one square inch per 4,000
BTU/Hr. of total input of all appliances in the space.
2. When communicating with outdoors by means of
horizontal ducts, each opening shall have a free area
of not less than one square inch per 2,000 BTU/Hr. of
total input of all appliances in the space.
For detailed requirements see:
• in Canada, CAN/CGA-B149 Installation Codes
• in U.S.A., ANSIZ223.1-latest edition, National Fuel Gas
Code.
WARNING!
1. Flamma le materials, gasoline, pressurized containers,
or any other items or articles that are potentially fire
hazards must never e placed on or adjacent to the
heater. The appliance area must e kept free of all
com usti le materials, gasoline and other flamma le
vapors and liquids.
2. Do not o struct the flow of com ustion and ventilation
air to the appliance.
LEARAN E
The WR430-3K is design certified for installation on a
com usti le wall and for installation in an alcove or closet
with minimum clearances to com usti le construction of 0
mm from ack, 102 mm (4 inches) from sides, 305 mm (12
inches) from top and ottom, and 102 mm (4 inches) from
front. A minimum of 305 mm (12 inches) shall e allowed
for maintenance of servicea le parts. Clearance from vent
is dependent upon the clearance rating of the venting
material used; see venting page 6.
THIS APPLIANCE MUST BE INSTALLED IN ACCORDANCE WITH THE NATIONAL FUEL GAS CODE ANSI Z223.1-
latest edition in U.S.A. or CAN/CGA-B149 INSTALLATION CODES IN CANADA. LOCAL CODES AND/OR THE
REQUIREMENTS OF THE AUTHORITY HAVING JURISDICTION MUST BE FOLLOWED.
MOUNTING
The WR430-3K is design certified for mounting to a wall.
The heater must not e installed on a carpeted wall. The
heater must e mounted to the wall using appropriate
anchoring materials.
Note: If wall is a stud wall sheathed with plaster oard it is
recommended that support oard(s), either 1 x 4's
or 1/2” (minimum) plywood first e attached across
a pair of studs and then the heaters should e
attached to the support oards. See Figure 2.
Figure 2
Fig. 2 - Mounting the Heater
WALL STUDS
1” X 4”
SPACE BOARD
SUPPORT BOARD

6
Bosch POWER VENTING SYSTEM
INTRODU TION
Bosch power venting models are designed to overcome difficult venting pro lems which cannot e performed
with atmospheric venting: to meet your hot water demand load very efficiently, with an environmentally friendly
appliance which conserves energy and significantly reduces com ustion emissions to atmosphere.
GENERAL INFORMATION
This Power Vent System must e installed y a *qualified installer in accordance with all applica le local gas
and electrical codes and in the a sence of:
• With the current CAN1/CGA B149 installation code for gas urning appliances and the Canadian Electrical
code C22.1-M90 part 1 (for anada).
• With the National Fuel Code and the ANSI Z223.1-LATEST and National Electrical Code ANSI/NFPA No
70-LATEST electrical code (for USA).
The Bosch warranty will e voided y, and Bosch disclaims any responsi ility for the following actions:
• Use of any unapproved venting component part not manufactured or approved y Bosch in com ination
with the Bosch WR430-3K unit.
• The Bosch WR430-3K must not e modified in any way when installing the Power Vent System. All
systems must e installed as per Bosch Installation Guide.
• Installation other than instructed in this manual.
AUTION:
Bosch Power Vent System must be installed by a qualified agency in accordance with these instructions.
If improperly installed a hazardous condition such as an explosion or arbon Monoxide poisoning
could result. Bosch will not be responsible for any and all improperly installed appliances.
*QUALIFIED INSTALLING AGEN Y: Any individual, firm, corporation or company which either in person or
through a representative is engaged in and is responsi le for the installation and operation of gas appliances and
draft control devices, who is experienced in such work, familiar with all precautions required, and has complied
with all the requirements of the authority having jurisdiction.
GENERAL VENTING INFORMATION
SIZING & DISTAN ES:
Plan the vent system so that code clearances and manufacturer’s distances are maintained from com usti le
materials, plum ing and wiring.
This unit may e directly connected to approved vent termination with a 90° el ow or located with a maximum
lineal length of 15 ft. (4.6m) including two 90° el ows from termination. All vent pipe and fittings must only e
4” (10.2cm) in diameter.

7
Bosch POWER VENTING SYSTEM
GENERAL VENTING INFORMATION - continued
APPROVED VENTING MATERIALS:
Single wall:
As gauge listed in the current CAN1/CGA B149 installation code for gas urning appliances (for Canada),
National Fuel Code ANSI Z223.1-LATEST (for USA).
Note: annot be used in concealed locations.
B-Vent materials:
Straight lengths only (no el ow) may e used under following conditions
(i) Unsealed 5” B-vent may e used as a chase for sealed 4” single wall through concealed or unheated
areas.
learances to combustible materials for walls and partitions:
• 1” (25mm) for B-Vent.
• 3” (76mm) for single wall and uninsulated PVS-1 vent piping.
A wall thim le must e installed for internal wall applications.
All runs through unheated space or exposed to outside temperatures must e insulated to prevent condensation.
All portions of the vent system under positive pressure during operation (on the outlet side of the WR430-3K)
shall e sealed with high temperature silicone and high temperature aluminum duct tape and installed so as to
prevent leakage of flue or vent gases into uilding.
GENERAL ODE REQUIREMENTS
Before commencing an installation always consult with local gas and electrical codes and authorities, in the
a sence must e installed:
• With the current CAN1/CGA B149 installation code for gas urning appliances and the Canadian Electrical
code C22.1-M90 part 1 (for anada).
• With the National Fuel Code and the ANSI Z223.1-LATEST and National Electrical Code ANSI/NFPA No 70-
LATEST electrical code (for USA).

8
Bosch POWER VENTING SYSTEM
VENT TERMINAL INSTALLATION:
Before installing Bosch WR430-3K determine the location of vent system termination which may e immediately
connected with a 90° el ow or with a maximum lineal length of 15 feet including two 90° el ows. (See Fig. 1)
Note: In cold climate areas negative air pressure such as unbalanced heating and ventilating systems can
cause reverse air flows in gas vent and chimney systems. Under extreme cold conditions this can cause
freezing and damage Bosch heat exchanger during prolonged period of times when they are not in use,
such as night time hours. Vent termination with back draft flapper is supplied in order to minimize outside
air infiltration and risk of freezing equipment.
The approved terminal shall e so arranged for flue gases to e directed in a manner which will not jeopardize
people, overheat com usti le structures or enter into uildings, and that proper clearances are maintained (See
Fig. 2 )
a) The vent terminal of this Power Vent System shall not e less than 7 feet (213cm) a ove grade when
located in areas accessi le to pu lic walkways.
) A vent terminal shall terminate at least 3 feet (91cm) a ove and a minimum of 10 feet (305cm) horizontally
from any (mechanical) air inlet.
c) The vent terminal shall not e within 6 feet (183cm) radius from a gas meter or regulator, and horizontally
it must e a minimum of 3 feet (91cm) from the centre line of such regulator.
d) The vent terminal shall e a minimum of 6 feet (182cm) from any com ustion air inlet.
e) The vent terminal shall terminate from an opening window, at least 4 feet (122cm) elow or elow the
opening and 12 inches (30cm) horizontally. From a door 1 foot (30cm) a ove and 9 inches (23cm)
horizontally.
f) The vent terminal shall not e less than 3 feet (91cm) from an adjacent uilding.
g) The vent terminal shall not e less than 2 feet (61cm) a ove grade.
90° el
12 ft straight
(5.7m)
90° el
90° el
90° el
15 ft straight
(4.6m)
3 ft straight
(0.3m)
MAXIMUM LENGTH OF ALL PIPE LENGTHS
MUST NOT EX EED 15 FT (4.6M)

9
Bosch POWER VENTING SYSTEM
VENT INSTALLATION
1. Choose approved terminal location
2. Cut vent terminal opening through outside wall - Refer to installation instructions supplied with termination.
3. Install vent terminal y fastening from outside with 4 screws and caulking around flange edge. Check that
optional flapper moves freely if applica le.
4. Install 4” venting materials and secure all joints with a minimum of four screws for each joint. Please note that
wherever possi le use continual lengths of pipe to reduce the num er of joints.
5. Seal all positive vent pipe and el ow joints etween Bosch unit and vent terminal with high temperature
silicone and/or hi temperature aluminum tape following manufacturer’s instructions (i.e. always push silicone
ahead of nozzle)
ELE TRI AL WIRING:
1. The electrical contact ratings are as follows:
______ 1/10 HP at 120 VAC
______ 3 Amps (full load) at 120 VA
2. Provide switched plug receptacle to accommodate Bosch grounded plug.
3. Make certain the power source is adequate for the fan motor requirements.
Figure 2
REGULATOR VENT
72”
72”
36” 36”

10
Bosch POWER VENTING SYSTEM
VENT INSTALLATION (continued)
6. Support venting duct with plum er’s strap (supplied y installer). Solid piping need only e supported every
four feet. All horizontal pipe joints must e secured with a minimum of four screws per joint. (See Figure 3)
7. All runs through unheated spaces must e wrapped and insulated with a minimum of 1” insulation.
OPERATION AND HE KING THE DRAFT
A. Place Bosch appliance into operation. Follow lighting pilot and operating instructions on Bosch
cover.
1. Draw water continuously to activate appliance which will turn on gas urner.
2. CHECKING THE DRAFT. Operate the appliance with cover in place for a minimum of five minutes and
check for proper venting, and assure that the com ustion products are venting properly, y passing a
lighted match flame or smoke taper over the top edge of the Bosch cover and towards draft hood. If the
vent is drawing properly, the smoke or match flame will e drawn over the top edge of the Bosch cover
and into the draft hood or opening. (see drawing elow Checking The Draft)
NOTE: If smoke is not drawn in then the combustion products are
escaping from the relief opening into the room. Under these
conditions, the equipment shall not be operated until proper
adjustments or repairs are made to provide adequate draft.
3. Check draft spill safety switch y o structing outside vent terminal and y drawing water. Spill switch
should trip and shut off gas supply to Bosch unit. Remove outside o struction.
4. If spill switch trips allow 5 minutes to reset.
HE KING THE DRAFT
Figure 3
Vent support hangers (plum er's
strapping) should e 4 ft. apart on
horizontal runs.
All joints must e sealed with high temperature silicone
and high temperature aluminum vent pipe tape
RIGID PIPE
positive pressure
All clamped joints on the positive
side of the power venter are to
e sealed with high temperature
silicone.
Use 4 screws
per joint

11
Bosch POWER VENTING SYSTEM
B. The Air-Flow Adjustment on the Power Venter is factory set for optimum air flow. Operating at its setting will
assure that com ustion gases are safely removed to the outside.
MAINTENAN E
Points of inspection are:
1. Motor - Motor must rotate freely.
2. Fan Wheel - Wheel must e clean of dust or any other coating which inhi its rotation or air flow. Remove
all foreign material from vent system efore operation.
3. Spill Switch - Verify proper spill switch operation y o serving Operation Sequence and y temporarily
locking termination outlet.
4. Check Draft - Check for flue gas spillage following steps in the Operation And Checking Draft on
page 9.
5. Vent Termination - Inspect to ensure installation and clearances have not een altered or o structed and
that the ack draft flapper (when used) movement is free and operational. Note that terminal hood is
remova le for easy flapper maintenance or replacement.
Hinge
Vent termination hood
Flapper

12
DRIP TRAY
If the water heater is eing mounted a ove a floor of
com usti le construction the drip tray (shipped loose in the
carton with the water heater) must e attached to the ottom
of the front cover of the water heater at the time of
installation. The drip tray should e attached to the front
cover, using screws provided, as shown in Figure 3.
Failure to use drip tray when installing unit a ove a floor of
com usi le construction will cause an unsafe condition and
possi le fire and will e in violation of A.G.A. and C.G.A.
certification of the unit.
Figure 3.
Water valve and S-bends, top view
WATER ONNE TIONS
The BOSCH instantaneous water heaters are provided with
two S- end water connectors/adaptors that must e
connected to inlet and outlet connections on water valve
assem ly, see Figure 5, elow.
Figure 5.
The purpose of the S- end water connectors/adaptors is to
provide threaded water connections that meet standards
used in North America, ANSI Standard Taper Pipe Thread
(1/2” NPT). The cold water supply should e connected to
S- end attached to inlet of water valve and the hot water
connection should e made to S- end attached to the outlet
of water valve.
If plastic piping is to e used, a 1.5 meter (approx. 5 feet)
length of metal piping must first e attached to oth the
cold water inlet and hot water outlet of the water heater.
Note: A shut-off valve should e placed in the cold water
supply line to the heater to facilitate servicing the
heater.
SCREWS
INCANDESCENT PARTICLE TRAY

13
RELIEF VALVE
The listed pressure relief valve supplied must e installed
near the hot water outlet at time of installation of the heater.
No valve is to e placed etween the relief valve and the
heater. A drain line must e connected to the relief valve to
direct discharge to a safe location. Do not install reducing
coupling or any other restriction in the discharge line. The
discharge line must e installed so as to allow complete
drainage of oth the valve and the line. See figure 6.
Figure 6.
Check to make sure that the gas listed on the rating plate is
same as gas listed on the pressure regulator. See
PRESSURE REGULATION section of this manual for
information regarding gas pressure settings.
Note: Before attaching the gas supply line, e sure that all
gas pipe is clean on the inside. To trap any dirt or
foreign material in the gas supply line, a drip leg must
e incorporated in the piping. The drip leg must e
readily accessi le and not su ject to freezing
conditions. Install in accordance with the
recommendations of serving gas supplier.
Joint compounds (pipe dope) shall e applied sparingly and
only to the male threads of pipe joints. Do not apply
compound to the first two threads. The joint compound must
e resistant to the action of liquified petroleum gases.
Before placing water heater in operation, check for gas
leakage. Soap and water solution, or other material
accepta le for this purpose shall e used in locating gas
leaks. Matches, candles, lighters, or other ignition sources
shall not e used for this purpose.
WARNING
The heater and its individual shutoff valves must e
disconnected from the gas supply piping system during any
pressure testing of that system at test pressures in excess
of 3.45 kPa (1/2 psig).
The water heater, including the pressure regulator provided
with it, must not e operated at gas supply pressures in
excess of 3.45 kPa (1/2 psig). If overpressure has occurred
such as through improper testing of the gas lines or
emergency malfunction of the supply system, the gas valve
and regulator must e checked for safe operation. Make
sure that the outside vent valves are protected against
lockage. These are part of the gas supply system, not the
water heater. Vent lockage may occur during ice storms.
Figure 7(a) Gas Burner test point D for measuring urner
manifold pressure at full flow and input:
Standard Altitude: 4.58”W.C. Nat Gas, 9.11”W.C. Propane.
High Altitude: 3.73”W.C. Nat Gas, 7.27”W.C. Propane.
GAS ONNE TIONS
Before connecting the gas supply to the heater, check
heater’s model/rating plate to make sure that the gas on
which heater is to operate is the same as specified on the
model/rating plate.
The WR400-3.K.. instantaneous water heaters are supplied
with a gas pressure regulator that must e installed on the
heater efore attaching the gas supply line. See figure 7.
Failure to install the gas pressure regulator as shown in
figure 7 will e a violation of A.G.A. and C.G.A. certification
of the unit.
BOSCH water heaters are shipped from the factory with
the gas pressure regulators preset for the gas shown on the
rating plate to the correct pressure:
• in Canada, for high altitude operation;
• in U.S.A., for standard altitude operation unless
specifically marked as a high altitude unit.
HWSHWS CWSCWS
Pressure
Relief
Valve
Pressure
Relief
Valve
GAS INLET PIPE
PRESSURE TAP T
APPLIANCE PRESSURE
REGULATOR
Figure 7. GAS MANIFOLD PRESSURE TEST POINT
T For measuring correct regulator operating pressure.

14
OPERATING INSTRU TIONS
WARNING!
If the water heater has een damaged or exposed to fire or
sooting, or if any part has een underwater, do not use. If
unit has een operated during construction or alterations
and exposed to a ove normal dust levels the heat exchanger
should e examined and cleaned regularly. Operation with
dust o structed fins could e a health hazard. 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 een underwater and to clean the heat
exchanger assem ly and water valve.
FILLING
Before proceeding with operation of the water heater make
sure that the system is filled with water:
• Make sure drain is closed. See figure 8, elow.
• Open a near y hot water faucet to permit the water to
fill the heater and piping.
• Close the hot water faucet after the water flows freely
and all air has escaped from the system.
The water heater is now ready to e lit.
To operate the heater, set the ON/OFF switch to position
I. The switch is located behind the flip down cover plate
on the front panel strip.
To shut down the heater, set the ON/OFF switch to
position O.
Figure 10
Figure 8
SERVI E HINT
The screen (strainer) in the water valve, located in the inlet
of the water valve, may require occasional cleaning due to
foreign material in the water supply. This will restrict the
flow of water and may affect heater operation and prolong
filling time. To inspect the strainer, close the cold water supply
valve ahead of the heater, disconnect the S- end from the
inlet of the water valve and remove strainer from inlet. Clean
if required, replace strainer in inlet to the water valve,
reconnect S- end and turn on water supply.
Light the water heater in accordance with the instructions
on the Lighting and Operating Plate on the water heater.
For your convenience, the instructions are repeated here:
LIGHTING AND OPERATING INSTRU TIONS
1. STOP! Read the safety information a ove on this la le.
2. The gas valve must e shut off y putting the ON/OFF
switch to position “o” Wait five (5) minutes to clear out
any gas. If you small gas, STOP! Follow “B” in the safety
information a ove. If you do not smell gas, go to the
next step.
3. This water heater is equipped with a safety pilot urner
and an automatic ignition control system.
4. Set the ON/OFF switch (flip down cover plate on frontal
panel strip) marked I/O to the I position. In this position,
the water heater is ready to use. (See Fig. 10).
5. Turn the hot water faucet on the minimum flow rate
required to activate the heater. The automatic ignition
system first ignites the safety pilot urner which then
ignites the main urner in a out 4 seconds.
6. The pilot flame will extiguish 10-30 seconds after the
urners come on. The urners will remain on until the
hot water tap is turned off.
7. Vent fan turns on and off with urner.
NOTE: On a first time initial installation, existence of air in
the gas supply line and in the water line may cause some
ignition delay. In that case, repeatedly open and close the
hot water tap in order to restart the ignition process until all
the air has een purged.
TO TURN OFF GAS TO APPLIAN E
Turn off the manual lever on the gas supply line to the heater
and set the ON/OFF switch to the OFF (O) position.
G667_091

15
*Note: The high altitude ratings listed are Canadian Gas Association
high altitude ratings for the appliances and are only valid in
Canada. In the U.S.A. the National Fuel Gas Code, ANSI 1-
1988, recommends for high altitude installations, a ove 2,000
feet, that the input rate e reduced 4% for each 1,000 feet
a ove sea level.
Figure 11
The gas pressures specified elow refer to flow pressure
taken at the pressure tap in the gas inlet pipe just a ove the
pressure regulator, (see figure 11) while the heater is
operating at full input.
Gas pressures read at urner test point D (see fig. 7(a)
page 12.
Table 1.
Appliance Regulator Pressure Setting
Your appliance dealer and/or your local gas supplier should
e consulted in regard to any high altitude installation. If
field adjustment is required it should e performed y a
qualified serviceman experienced in such work.
TEMPERATURE REGULATION
The BOSCH WR430-3K is equipped with a modulating
gas valve which adjusts the flow of gas to the main urner
in proportion to the water flow rate. Within its heating
capacity the WR430-3K attempts to maintain the set
temperature rise across the heater. This temperature rise
can e set in range of 25C° - to - 50C° (45F° - to - 90F°),
y means of the water flow selector. See Figure 12. When
the water flow selector is turned to the right hand stop the
water heater is set for 50C° (90F°) temperature rise; when
the water flow seletor is set to the left hand stop it is set for
25C° (45F°) temperature rise.
PRESSURE REGULATION
The pressure regulator supplied with the water heater is
adjusted to operate on the gas specified on the rating plate
and:
• in Canada, is factory preset to deliver gas at the high
altitude setting listed on the rating plate and as shown
elow.
• in the U.S.A., is factory preset to deliver gas at the
standard altitude setting listed on the rating plate and as
shown elow.
The pressure setting of the gas pressure regulator should
e checked at installation to assure that the setting is correct
for the gas eing used and the altitude at which the
appliance is installed. See rating plate on the unit, Ta le 1,
elow, for proper setting.
In Canada, for a heater eing installed at standard altitude
(0-2,000 ft a ove sea level) the manifold pressure should
e reset at installation to the value shown on the rating
plate, or Ta le 1, elow, for standard altitude.
Increases temperature
and decreases flow
Temperature Adjustment Knob
Decreases temperature
and increases flow
Figure 12 - Principles of Operation
Figure 12
With the water flow selector turned to its right hand stop
position (50C° rise setting) and with an inlet water
temperature of 10°C (50F°) the outlet water temperature
will e maintained at approximately 60C° (140F°) in the
water flow rate range of approximately 2 litres/min. (0.5 U.S.
gals./min.) to 9.5 litres/min. (2.5 U.S. gals./min.).
The minimum flow rate for operation, the “Threshold Flow
Rate” referred to in the lighting instructions is 2 litres/min
(0.5 U.S. gals./min.). If the water flow rate is elow this level
the main urner will not fire. If the flow rate exceeds 9.5
litres/min (2.5 U.S. gals./min.) the temperature rise aross
the heater will decrease in proportion to the rate a ove this
temperature.
HIGH TEMPERATURE LIMIT SWIT H
The BOSCH series instantaneous gas water heaters are
equipped with a high temperature limit switch with a set
point of approximately 90°C (195°F). If the water temperature
at the sensing points exceeds the set point the switch will
open, interrupting the safety circuit and stopping gas flow
to the pilot and main urner.
Outage as the result of high limit operation indicates that
the heater is not functioning properly. The heater should e
checked y a qualified serviceman and the reason for the
malfunction is corrected.
REGULATOR
SUPPLY TEST
PRESSURE TAP T
ADJUSTABLE
PRESSURE REGULATOR
kPa Inches, W.C.
natural 1.41 5.38 standard
propane 2.61 9.9 (0-2,000 ft.)
natural 1.14 4.4 high*
propane 2.09 7.9 (2,000-4,500 ft.)
Altitude
WR430-3K
Model Type of Gas Regulator Pressure Supply

16
MAINTENANCEANDSERVICE
Approximatelyonceayear,theBoschshouldbechecked,
cleaned and serviced as necessary. To remove the front
cover, first remove the incandescent particletray,thenpull
off the temperature adjustment knob and unscrew and
remove the plastic collar. Pull main cover out toward you
and lift up and out. THE FOLLOWING OPERATIONS
SHOULD BE PERFORMED BYAQUALIFIED SERVICE
PERSON:
VentSystem: Shouldbecheckedannually.Cleanandrepair
asneeded.See Preventative Maintenance Page 10.
Water Valve: The water valve on this heater should be
serviced periodically. The frequency will depend on the
mineral content of the water and conditions of use or
whenever signs of corrosion appear at the gas and water
valve joint. Check that the water inlet filter (#36 on Figure
19,page 20)isclean.Diaphragm shouldbereplaced every
7-8yrs.inresidentialapplicationsand3-5yrsforcommercial
applications.Inacid water areas theventurishouldalso be
replaced at the same time (#39 on Figure 19, page 20).
Pilot Flame: The pilot flame should burn with a clean,
sharp,blueflameand should resemble the diagram in Fig.
13. If the flame is soft and yellow the pilot screen may be
dirty or the pilot burner orifice may need to be cleaned or
replaced.The pilot flameshouldbe approximately2inches
long, extending past the flame sensor. If the flame is too
small, it will not reach the flame sensor and the burners
will not come on.
Do not enlarge the orifice.
Do not use any wire or sharp o ject to clean orifices. Natural
gas orifices are large enough that you can usually clean
them y lowing through them. To access the pilot orifice,
remove 2 screws holding pilot assem ly in place. Then loosen
compression fittings to expose pilot orifice.
Heat Exchanger should e visually examined once a year
or more often in dusty areas. If fins at top show dust or
de ris accumulation, remove and clean with rush and soapy
water.
Flame sensor
Electrode
Electrode
Fig. 13 - haracteristic Pilot Flame
To clean the pilot burner and/or the pilot orifice: Turn off
the gas to the unit. Set the On/Off switch to Off ( position
0). Remove the cover of the heater. To do so, pull off the
temperature adjustment kno and unscrew and remove the
plastic collar. Pull main cover out toward you and lift up and
out. The pilot orifice should e cleaned or replaced.
3mm
Correct gap etween pilot
urner tip and electrode tip
Main Burner Flames: The main urner flames should e
lue, with a more intense lue cone in the center core. Yellow
flames could e a sign of plugged or dirty urners, or a
lockage on the heat exchangers fins. If some urners have
yellow flames while others have good flames, it is likely that
dust, lint or spider we s have partially clogged the urner
venturis. To clean the urners, contact a gas service person.
Mineral Scale Build-up: In hard water areas the Bosch,
when operated at lower temperature settings, tend not to
accumulate mineral uildup. If however, the heater is used
at the higher temperature settings and the water has a high
mineral content, periodic descaling may e necessary. The
heating coil should e removed and flushed with a descaling
solution. Signs of scaling are rising outlet temperature and
knocking noises when water is flowing.
TROUBLE SHOOTING
Introduction
The Bosch WR430-3K burners are activated by a water
flow valve. Numerous water related roblems can cause
this water valve to malfunction such as: Insufficient water
flow volume to activate the burners at its minimum flow
requirement; Dirt in the water flow valve causing it to
malfunction; Sediment build-u in faucet aerators, or shower
heads; Uneven ressures between cold and hot, (with single
lever faucets) Plumbing cross overs. These water flow related
roblems can cause the heater to deliver less than its full
out ut, or to fail to ignite or to shut down com letely.
Pro lems are stated in upper case, old face. Most common
causes for the pro lems follow in order of likelihood. The
suggested solutions require that the cover e taken off. To
do this, remove incandescent particle tray, pull off the
temperature adjustment kno and unscrew and remove the
plastic collar. Pull main cover out toward you and lift up and
out.
Removal of the Heat Exchanger
1. Shut off the gas and water cold
supply lines to the heater and remove
the front cover.
2. Remove the drain screw from the
ottom of the water regulator and
open the hot water tap to allow the
unit to drain.
3. Remove cover and unscrew metal
retaining ar at the top front of the
heat exchanger
4. Undo water connection nuts at
heat exchanger from oth sides 5. Tilt the heating ody to the front
at the top and lift away from the
heater.
Estimated service time is 10 minutes to re & re, plus cleaning time
Pilot tu e
Pilot cap orifice

17
NO SPARK AT THE PILOT
1. ON/Off switch is not “On” (Position I).
The On/Off switch is located ehind the flipdown cover
plate on the front panel strip. See fig. 10.
2. Water flow is not sufficient to activate heater.
Water flow rate at faucet is elow minimum flow needed to
activate heater. When temperature adjustment kno is turned
all the way clockwise, the Bosch WR430-3K requires 1/2
gallon per minute flow to activate the heater. As a reference,
this is a flow which would fill a quart jar in 30 seonds. If the
temperature adjustment kno is turned fully
counterclockwise, a flow rate of 1.1 gallons/minute is required
to activate the heater.
3. Water inlet filter is clogged
Water flow is restricted, preventing needed flow to activate
heater. Clean water inlet filter screen.
4. ross over in water lines
To confirm there is no cross-over in the plum ing, shut off
the cold water supply to the Bosch water heater and open a
not water faucet. There should not e any water flowing at
that faucet. Water running is a sign of a plum ing cross
over. Consult your plum er.
5. Microswitch needs to be adjusted or replaced.
If you do not hear a click when a tap is opened, the
microswitch needs to e adjusted. See Fig 15 for adjustment.
Replace the microswitch if the adjustment does not solve
the pro lem.
Fig. 15 - Microswitch Adjustment
7. old incoming water connection made to wrong side
of heater
Make sure cold water inlet connection is on the right side of
heater when you are facing heater.
8. Water valve parts may be dirty of components damaged
First check that venturi is free of dirt particles. Water valve
and component parts must e totally free of dirt. In hard
water areas, mineral deposits can eventually (3-5 years in
hard water areas) corrode the water valve parts to a point
where they will need replacing. Any sign of moisture at the
top of the water valve is a sign that the water valve needs to
e serviced immediately.
9. Loose connection at the E O
Ignition sparker will not operate if the electrical circuit is
interrupted. Check that the connections to the ECO are
secure and tighten if necessary.
SPARKS APPEAR AT PILOT WHEN HOT WATER
TAP TURNED ON, BUT PILOT AND BURNERS
WILL NOT IGNITE
1. Air in the Gas Line
Normally this is a pro lem at time of initial installation, after
the pipes have een worked on, or after a gas supply line
has een allowed to empty. Bleed the air trapped in the gas
line y turning the hot water faucet on and off until the air
has een cleared from the line.
2. No gas to the Bosch
A. Gas cock on gas line may not e open
B. Gas regulator may e shut or damaged. Replace or unjam
the regulator. Note: The regulator furnished with the heater
is exclusively designed for low gas pressure. Excessive
pressure will lock it up. Jamming usually happens when using
propane gas if the gas pressure etween the gas tank and
the water heater’s gas regulator has not een reduced. See
Page 14 for recommended correct gas pressure. To unjam a
regulator, consult your gas supplier.
3. Pilot orifice or gas valve is dirty
Clogging of the pilot urner can e caused y dust in the
air or dirt in the gas. The pilot orifice or gas filter may need
to e cleaned or replace.
4. Water valve assembly needs to be checked
If the pilot orifice is clean, the water valve assem ly should
e checked. The adjustment screw on the water valve micro-
switch may not e tight enough (Fig. 15). Remove central
cap eneath micro-switch assem ly, carefully loosen the
adjustment screw until the pilot light ignites. At that point
retighten the screw one and a half turns.
5. Pilot electrovalve switch may need to be replaced (See
Fig 17).
Call your service person or call: Canada 1-800-663-8405,
U.S.A. 1.800-824-7337.
6. Electronic ontrol Box may need to be replaced, (See
Fig 17).
Call your service person or call: Canada 1-800-663-8405,
U.S.A. 1.800-824-7337.
Pilot does not spark with
water flow
1 Close water tap
2 Remove screw cap and
unscrew adjusting screw til
sparking starts
3 Screw in turning one and
half turns more
4 Replace screw cap
Pilot is always sparking
without water flow
1 Close water tap
2 Screw in adjusting screw, till it
stops sparking
3 Continue to screw in turning
one and a half turns more
ADJUSTING
SCREW

18
PILOT SPARKS ONTINUOUSLY WITH
NO WATER RUNNING
1. Microswitch needs adjustment
If no water is running, ut pilot electrode continuously sparks,
the microswitch screw to the water valve needs adjustment.
See Figure 16.
PILOT LIGHTS BUT BURNERS
WILL NOT OME ON
1. onfirm water valve assembly is working properly.
2. onfirm the flame sensor is in its proper position.
3. onfirm the burner electrovalve switch is functioning
properly. Contact your service person or call:
Canada 1-800-663-8405, U.S.A. 1.800-824-7337.
4. The electrical ontrol Box (Fig. 16) may need to be
replaced. Contact your service person or call:
Canada 1-800-663-8405, U.S.A. 1.800-824-7337.
MAIN BURNERS GO OUT DURING HOT
WATER USE
1. Flow rate diminished below activation rate: 0.5 USGM
(2.5 l) in hot position, 1.0 USGM (5 l) in warm position
2. Unbalanced pressure in the water lines
The added restriction caused y the Bosch in the hot water
system can result in uneven pressures etween the cold
and the hot. In such cases when mixing cold water at the
tap, the lower hot water pressure may e overpowered y a
much higher cold water pressure, which may cause the
Bosch urners to shut down. Make sure faucet aerators
and showerheads are free of minerals and dirt. Do not add
any flow restrictor to the shower head.
3. heck gas supply
4. E O (overheat sensor) tripped due to overheating
5. Minimum inlet pressure on well is inadequate
Check the inlet water pressure. On a private well, raise the
minimum pressure setting to 40 psi for est performance.
Confirm that the pressure tank is not water logged.
6. heck Blower Fan. Is it operating when urner comes
on?
7. Check flapper in outside vent termination for free
movement.
Fig. 16 - Electrical wiring diagram
E864_020
WATER IS TOO HOT
1. heck for lime build-up. (See mineral scale p. 15)
2. Temperature Selection too high
Turn the temperature adjustment kno counter-clockwise
(to the left) to lower the maximum water temperature.
Note: This will increase the activation flow rate.
3. Inlet water temperature is too hot (as with preheated
water.)
4. Insufficient water pressure
WATER IS NOT HOT ENOUGH
1. Temperature selection too low.
Change the setting. Turn the temperature adjustment kno
clockwise (to the right).
Note: This will decrease the activation flow rate.
2. Water flow through the heater is higher than the
capacity of the Bosch to heat it.
This can e due to too high water inlet pressure (60 psi
max. for est results) or due to acid water erosion of venturi.
Check venturi (Part #39, Fig. 19 page 20).
3. Btu input is too low due to insufficient gas pressure.
It is extremely important for a tankless instantaneous water
heater to have the right size gas line to obtain the correct
gas pressure.
See specifications on page 14, ta le 1. Unlike storage tank
water heaters, the urners of a tankless water heater must
e very powerful to heat water instantaneously since they
do this only at the time hot water is actually eing used. It is
therefore imperative that the gas pressure requirement e
met exactly. Insufficient gas pressure will directly affect the
water temperature at the time of usage. See page 14 for
correct gas pressure settings and fig. 11 for locations where
gas pressures are taken.
4. Btu input is too low due to insufficient gas supply.
Make sure your main gas line is fully opened. If using LP
gas, e sure that the size of the propane tank is adequate to
supply the required gas pressure.
5. old water is mixing with the hot water between the
Bosch and the outlet.
Compare water temperature at outlet of the Bosch (hold
the Bosch’s outlet pipe with your hand) and at the tap. If
these two are very different, check for mixing valve or
plum ing crossover (see “NO SPARK AT THE PILOT”
paragraph #4). Where automatic “anti-scald” valves are
required y code, lower the temperature setting on the Bosch
as much as possi le and alance the pressure etween
cold and hot water after the Bosch.

19
2. old water is mixing with the hot water between the
Bosch and the outlet.
See 4 under “NO SPARK AT THE PILOT”.
3. Inlet water pressure is erratic due to inadequate supply
water pressure or saturated pressure tank on well
system.
Check the inlet water pressure. On a private well, raise
minimum pressure setting to 40 psi. Confirm that the
pressure tank is not water logged.
4. Gas pressure is too low.
See page 14 for correct specifications.
Fig. 17 - Diagram of WR430-3K
6. Parts in water flow valve are corroded so that the
gas passage is not fully opening.
Contact your service person or call:
Canada 1-800-663-8405, U.S.A. 1-800-824-7337.
HOT WATER TEMPERATURE
FLU TUATES
1. Unbalanced pressure in waterlines.
The added restriction caused y the Bosch in the hot water
system can result in uneven pressures etween the cold
and the hot. In such cases when mixing cold water at the
tap, the lower hot water pressure may e overpowered y a
much higher cold water pressure, which may cause the
Bosch urners to shut down. Make sure faucet aerators or
shower heads are free of minerals. Do not add any flow
restrictor to the shower head.
5
11
1
4
9
10
12
2
6
8
7
13
14
3
1. Heat exchanger
2. Pilot assem ly
3. Burner manifold gas
pressure test nipple
4. Main gas urner
5. Pilot gas tu ing
6. Gas valve
7. Electronic control ox
8. Power cord
9. on/off switch
10. Temperature
adjustment selector
11. Microswitch
12. Gas inlet gas pressure
test nipple
13. Electric ox
14. Exhaust Fan
See fig 7(a) on
page 12
See table 1 on
page 14

20
Fig. 18
INTERIOR OMPONENTS DIAGRAM
AND PARTS LIST WR430
1 Front Cover 8 705 421 255
2 Bosch Decal 8 701 103 050
3 Plastic lower snap-on 8 705 506 451
4 Temperature adjustment kno complete 8 702 000 219
5 Temperature adjustment kno 8 702 000 111
6 Exhaust fan assem ly 8 707 204 023
7 Draft diverter 8 705 505 451
8 Fan protection 8 701 302 164
9 Flue gas safety device 8 707 206 185
10 Heat Exchanger 8 705 406 235
11 Hot water pipe 8 700 705 556
12 Washer 8 710 103 045
13 Overheat sensor (ECO) 8 707 206 040
14 Cold water pipe 8 700 705 294
15 Main urner assem ly 8 708 120 298 NG
8 708 120 296 LP
16 Washer for urner assem ly 8 710 103 060
17 Throttle disc 8 700 100 189 LP only
18 Gas Valve 8 707 011 811 NG
8 707 011 812 LP
19 Diaphragm switch 8 708 504 021 NG
8 708 504 049 LP
20 Main solenoid valve 8 708 501 250
21 Pilot solenoid valve 8 708 501 249
22 O-ring 8 700 205 120
23 Electrode ignition group 8 718 107 067
24 Pilot urner assem ly 8 708 105 337 NG
8 708 105 491 LP
25 Pilot orifice 8 708 200 069 NG
8 708 200 312 LP
26 Pilot gas tu e 8 700 707 349
27 Washer 8 700 103 173
28 Electronic control ox 8 707 207 011
29 Electric control ox 8 707 101 021
30 On/Off switch 8 707 200 014
31 Microswitch 8 707 200 007
32 Water valve 8 707 002 534
33 Water valve repair kit 8 703 406 178
34 Slow ignition valve 8 708 503 063
35 Diaphragm 8 700 503 053
36 Water inlet filter 8 700 507 045
37 Selector screw 8 708 500 251
38 Volumetric water governor 8 707 402 015
39 Venturi 8 708 205 249
40 Cover complete 8 705 500 076