Bosch WR400-1K, WR400-1 K P Installation Operation & Maintenance

Instantaneous gas water heater

Models
WR400-1K…

· 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.

Suitable for heating potable water only. Not approved
for space heating purposes.

READ INSTRUCTIONS CAREFULLY BEFORE INSTALLING

NOTICE TO INSTALLER: Please leave this manual with

the owner or affix adjacent to
appliance.

ASTRAVAN DISTRIBUTORS, LTD.

6 720 603 100 (03.05) AL

123 Charles Street
North Vancouver, BC. V7H 1S1

Phone Canada: [phone]
Phone USA: [phone]
Web Site: www.astravan.com

WARNING: If the information in this manual is not
followed exactly, a fire or explosion may result
causing property damage, personal injury or death.

- Do not store or use gasoline or other flammable
vapors and liquids in the vicinity of this or any
other appliance.

- 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.

Note: In case of problems please contact your salesman or installer.

DIMENSIONS

Figure 1

Maximum hydrostatic water pressure – 1.03 Mpa (150 p.s.i.)
Maximum recommend working pressure – 0.69 Mpa (100 p.s.i.)
Minimum working pressure – 0.0138 Mpa (2 p.s.i.) at 2 Litres/min. (0.5 U.S. Gallons/min) free discharge

Minimum recommended inlet water pressure for use with showers 40 p.s.i.g.

Dimensions in Milimetres (inches)

Model dimensions A B D E F

WR400 - 1

Model Type of gas Altitude Input

WR400

WR400

milimetres

inches

Natural

Propane/LP 0.79 diam. 18

Natural

Propane/LP 0.79 diam. 18

460 755 130 diam. 740 542

18 1/8 29 3/4 5 1/8 diam. 29 1/8 21 11/32

Main Burner Orifices

Size, mm Qt.

standard 34.28 kW 1.20 diam. 18

(0 - 2,000 Pieds) (117,000Btu/hr)

high* 30.85 kW 1.20 diam. 18

(2,000 - 4,500 Pieds) ( 105,000Btu/hr)

* The high altitude ratings listed are Canadian Gas Association high altitude ratings and are only valid in Canada. In the

U.S., the National Fuel Gas Code, ANSI Z223.1/NFPA 54, recommends for high altitude installations above 2,000 feet,
that the input rate be reduced 4% for each 1,000 feet above sea level. – See page 8.

2

FOREWORD

This design complies with CAN1-4.3-77 and ANS1Z21.10.3b
1994 as an instantaneous gas water heater. In addition the
unit complies with CAN1-2.17- M80 use at high altitude,

2.000- 4.500 feet above sea level.

Installation, operation and maintenance information is
provided in this manual . Installation and operation
instructions should be thoroughly reviewed before
proceeding with installation of the BOSCH instantaneous
gas water heater.

The BOSCH instantaneous gas water heater is designed
to operate on natural or propane gas; however make sure
that gas on which heter is to operate is the same as specified
on the heater’s model/rating plate.

In addition of these instructions, the water heater shall be
installed in accordance with CAN1-B149 Installation Code
(in Canada) or ANSI Z223-1/NFFA 54 National Fuel Gas
Code (in U.S.) and/or local installation codes.
These shall be carefully followed in all cases.

INSTALLATION INSTRUCTIONS

Note: Proper plumbing, venting, gas connections and an

adequate supply of combustion air are required for
safe and reliable operation. Ability equivalent to that
of a licensed tradesman in the field involved is required
for installation and/or service of these water heaters.

LOCATION

Before installing the BOSCH instantaneous water heater
consideration must be given to proper location. The location
should be as close to a chimney or gas vent as practicable,
in an area with an adequate air supply and as centralized
with the piping system as possible. The heater should not
be located in an area where it will be subject to freezing.
The heater should be 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.

Note: When such locations cannot be avoided, it is

recommended that a suitable drain pan, adequately
drained, be installed under the water heater. The
pan must no restrict combustion air flow.

AIR REQUIREMENTS

For safe operation, sufficient air combustion, ventilation and
dilution of the flue gas must be available. An insufficient
supply of air will result in a yellow luminous burner flame,
causing carboning or sooting of the heat exchanger.

In order to prevent corrosion, make sure that the combustion
air is kept free of aggressive substances. Substances that
especially contribute to corrosion are halogenated
hydrocarbons (e.g., chlorine and fluorine) which are
contained in solvents, paint, adhesives, propellant gases,
various household cleaners, etc. Take precautionary
measures as necessary.

In unconfined spaces, in buildings of normal construction,
infiltration normally is adequate to provide air for combustion,
ventilation and dilution of the flue gases. However, a confined
space must be provided with two permanent openings to
provide combustion and ventilation air to the appliance. Each
opening shall have a free area on one square inch per 1,000
BTU/Hr* of total input rating of all the appliances in the
enclosure. One opening shall be within 12 inches of the top
and one within 12 inches of the bottom of the enclosure.

*Special Note

When the WR400-1 is installed in a confined space of
minimum size the openings described above must be
increased in to a size of 1 ½ square inches per 1,000 BTU/
Hr. In order words, when the WR400-1 is installed in a
minimum sized confined space the two openings that are to
be made in the enclosure within 12 inches of the top and
12 inches of the bottom must each have a minimum free

area of (1 ½ “) x (117) = 175.5 square inches.

3

For either a confined or unconfined space in a building of
tight construction with inadequate infiltration, air must be
drawn from the outdoors or from spaces that freely
communicate with the outdoors. Two permanent openings
located as indicated above are to be 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.

MOUNTING

The WR400-1 is design certified for mounting to a wall.
The heater must not be installed on a carpeted wall. The
heater must be mounted to the wall using appropriate
anchoring materials.

Note: If wall is a stud wall sheathed with plasterboard it is
recommended that support board(s), either 1 x 4’s or ½ “
(minimum) plywood first be attached across a pair of studs
and then the heaters should be attached to the support
boards. See Figure 2.

For detailed requirements see:

• In Canada, CAN/CGA- B149 Installation Codes

• In U.S.A., ANSI Z223.1/NFPA 54, National Fuel Gas

Code.

WARNING!

1. Flammable materials gasoline, pressurized
containers, or any other items or articles that are
potentially fire hazards must never 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.

2. Do not obstruct the flow of combustion and
ventilation air to the appliance.

CLEARANCE

The WR400-1 is design certified for installation on a
combustible wall and for installation in an alcove or closet
with minimum clearances to combustible construction of
0mm from back, 102mm (4 inches) from sides, 305mm (12
inches) from top and bottom, and 102mm (4 inches) from
front. A minimum of 305mm (12 inches) shall be allowed for
maintenance of serviceable parts. Clearance from vent is
dependent upon the clearance rating of the venting material
used; type B-1 vent is approved for 1 inch clearance, B-2
vent for 2 inch, etc.

WALL STUDS

1”X4” SUPPORT BOARDS

Figure 2

Expansion and contraction of piping due to changing water
temperature in the pipes imparts movement to the heater
which, if mounted directly to a brittle, friable board, such as
plasterboard, can cause failure of mounting.

THIS APPLIANCE MUST BE INSTALLED IN ACCORDANCE WITH THE NATIONAL FUEL GAS CODE ANSI Z223.1/
NFPA 54 IN U.S.A OR CAN/CGA- B149 INSTALLATION CODES IN CANADA. LOCAL CODES AND/OR
REQUIREMENTS OF THE AUTHORITY HAVING JURISDICTION MUST BE FOLLOWED.

4

DRIP TRAY

If the water heater is being mounted above a floor of
combustible construction the drip tray ( shipped loose in
the carton with the water heater) must be attached to the
bottom of the front cover of the water heater at the time of
installation. The drip tray should be attached to the front
cover, using screws provided, as shown in Figure 3.

Failure to use drip tray when installing unit above a floor of
combustible construction will cause an unsafe condition and
possible fire and will be in violation of A.G.A. and C.G.A

certification of the unit.

For high altitude use the adaptor must be installed as shown
in Figure 4, without alteration, before connecting the six
inch flue to the unit. The adaptor must be secured to the
draft diverter outlet with a minimum of two screws.

Also, in Canada, the gas pressure regulator supplied with
the water heater is factory preset to deliver gas to the water
heater at the proper pressure setting for high altitude
operation, see PRESSURE REGULATION section of this
manual.

WARNING!

Failure to increase the vent size of the WR400-1 to six
inches and/or to assure that manifold pressure is set to proper
value listed on rating plate for applications at altitudes in
range of 2,000 to 4,500 ft. above sea level will cause unsafe
venting, asphyxiation, and voids C.G.A. Certification.

WATER CONNECTIONS

DRIP TRAY

Figure 3

VENTING

The BOSCH instantaneous water heaters have built-in draft
diverters and are designed for indoor installation only. The
draft diverter outlet must be connected to a clear,
unobstracted vent of the same size, or larger, refer to:

• In Canada, CAN/CGA- B149 Installation Codes for
detailed requirements.

• In U.S.A., ANSI Z223.1/NFPA 54, National Fuel Gas
Code for detailed requirements.

The flue connection for the WR400-1 is 130 mm (5 inches);
however, in Canada for installations at high altitude (2,000­4,500 ft. above sea level) a six inch (6”) flue is required.

5” x 6” adaptor used
on high altitude model
WR 400 only

The BOSCH instantaneous water heaters are provided with
two S- bend water connectors/adaptors that must be
connected to inlet and outlet connections on water valve
assembly, see Figure 1 and Figure 5, below.

Water valve and S-bends, top view

Figure 5

The purpose of the S- bend 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 be connected to
S- bend attached to inlet of water valve and the hot water
connection should be made to S- bend attached to the outlet
of water valve.

Figure 4

If plastic piping is to be used, a 1.5 meter (approx. 5 feet)
length of metal piping must be attached to both the cold
water inlet and hot water outleet of the water heater.

Note: A shut-off valve should be placed in the cold water

supply line to the heater to facilitate servicing the
heater.

5

RELIEF VALVE

The listed pressure relief valve supplied must be installed
near the hot water outlet at time of installation of the heater.
No valve is to be placed between the relief valve and the
heater. A drain line must be 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 be installed so as to allow complete
drainage of both the valve and the line. See figure 6.

Figure 6

Check to make sure that the gas listed on the rating plate is
the same as the 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, be 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
be readily accessible and not subject to freezing
conditions. Install in accordance with the
recommendations of the serving gas supplier.

Joint compounds (pipe dope) shall be applied sparingly and
only to the male threads of pipe joints. Do not apply
compound to the first two threads. The joint compound used
must be 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
acceptable for this purpose, shall be used in locating gas
leaks. Matches, candles, lighters, or other ignition sources
shall not be used for this purpose.

GAS CONNECTIONS

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 WR400-1 instantaneous water heaters are supplied
with a gas pressure regulator that must be installed on the
heater before attaching the gas supply line. See figure 7.
Failure to install the gas pressure regulator as shown in
figure 7 will be 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.

WARNING!

The heater and its individual shutoff valve must be
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 must be isolated from the gas supply piping
system by closing its individual manual shutoff valve during
any pressure testing of the gas supply piping system at test
pressures equal to or less than 3.45 kPa (1/2 psig).

The water heater, including the pressure regulator provided
with in, must not be 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 be checked for safe operation. Make
sure that the outside vent valves are protected against
blockage. These are part of the gas supply system, not the
water heater. Vent blockage may occur during ice storms.

Figure 7

6

GAS INLET PIPE

PRESSURE TAP

PRESSURE
REGULATOR

OPERATING INSTRUCTIONS

WARNING!

If the water heater has been damaged or exposed to fire or
sooting, or if any part has been underwater, do not use.
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 and to clean
the heat exchanger assembly 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, below.

• Open a nearby 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 be lit.

LIGHTING INSTRUCTIONS

1. STOP! Read the safety information above on this plate.

2. The gas valve should be turned off by sliding the gas
valve button to the far left, under the “OFF” mark, .

3. Wait five (5) minutes to clear out any gas. If you then
smell gas, STOP! Follow “B” in the safety information
above on this plate. If you don’t smell gas, go to next
step.

4. The pilot burner is located behind the peephole located
in the front center of the jacket directly below this
instruction plate.

5. Slide the gas valve button to the right, under “PILOT”
MARK, .

6. Fully depress the gas valve button and light the pilot by
pressing the “PILOT IGNITER” button, . This may
have to be repeated.

7. Observe the pilot flame through the peephole. The gas
valve button should be held down at least 10 seconds
with pilot burning. When the gas valve button is released
the pilot should continue to burn:

• If the gas valve button does not pop up when released
stop and immediately call your service technician or
gas supplier.

• If the pilot does not stay lit, repeat steps 1 through 7.

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

gas valve button to the left under the “OFF” mark and
call your service technician or gas supplier.

Figure 8

SERVICE HINT

The strainer (screen) 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 effect heater operation and prolong
filling time. To inspect the strainer, close the cold water supply
valve ahead of the heater, disconnect the S- bend 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- bend 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 below:

8. Slide gas valve button to the far right, under the “ON”
mark . The heater will now fire when water is drawn
at a rate greater than the threshold flow rate (see
manual*).

Note: If main burner should fail to ignite, make sure pilot is
burning. If not, repeat lighting procedure steps 1 through 8.

TO TURN OFF GAS TO APPLIANCE

1. Slide the gas valve button to the far left, off position,
under the “OFF” mark, and close the heater’s

individual shutoff valve.

* = see TEMPERATURE REGULATION section.

7

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 pressure setting listed on the rating plate and
as shown below;

· In the U.S.A., is factory preset to deliver gas at the
standard altitude setting listed on the rating plate and
as shown below.

The pressure setting of the gas pressure regulator should
be checked at installation to assure that the setting is correct
for the gas being used and the altitude at which the
appliance is installed. See rating plate of the unit, or Table
1, below, for proper setting.

In Canada, for a heater being installed at standard altitude
(0- 2,000 ft. above sea level), the manifold pressure should
be reset at installation to value shown on the rating plate, or
Table 1, below, for standard altitude.

Your appliance dealer and/or your local gas supplier should
be consulted in regard to any high altitude installation. If
filed adjustment is required it should be performed by a quali­fied serviceman experienced in such work.

TEMPERATURE REGULATION

The BOSCH WR400-1 is equipped with a modulating gas
valve which adjusts the flow of gas to the main burner in
proportion to the water flow rate. Within its heating capac­ity the WR400-1 attempts to maintain burner in proportion
to the water flow rate. Within its heating capacity the
WR400-1 attempts to maintain the set temperature rise
across the heater. This temperature rise can be set in range
of 25ºC –to- 50ºC (45º F – to – 90ºF), by means of the
water flow selector. See figure 10. With the gas control
button slid all the way to the right under the “ON” position
mark @ when the water flow selector is turned to the right
hand stop the water flow selector is turned to the right hand
stop the water heater is set for 50ºC (90ºF) temperature
rise; when the water flow selector is set to the left hand

stop it is set for 25ºC (45ºF) temperature rise.

PRESSURE TAP

PRESSURE
REGULATOR

Figure 9

The gas pressure specified below refer to flow pressure taken
at the pressure tap in the gas inlet pipe (just above the
pressure regulator), see figure 9 while the heater is operating
at full input.

Type Pressure tap Altitude

of gas kPa inches W.C.

Natural 1.41 5.7 standard

Propane 2.61 10.5 (0 - 2,000 ft)

Natural 1.14 4.6 high*

Propane 2.09 8.4 (2,000 - 4,500 ft)

* Note: The high altitude ratings listed are Canadien 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 Z223.1/NFPA 54,
recommends for high altitude installations, above
2,000 feet, that the input rate be reduced 4% for
each 1,000 feet above sea level.

GAS CONTROL
SLIDE

WATER FLOW
SELECTOR

Figure 10

With the water flow selector turned to its right hand stop
position (50ºC rise setting) and with an inlet water
temperature of 10ºC (50ºF) the outlet water temperature
will be maintained at approximately 60ºC (140ºF) in the water
flow rate range of approximately 2 litres/min. (0.5 U.S.gals/
min) to 8 litres /min. (2.1 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 below this level
the main burner will not fire. If the flow rate excess 8 litres/
min (2.1 U.S. gals/min.) the temperature rise across the heater
will decrease in proportion to the rate above this temperature.

HIGH TEMPERATURE LIMIT SWITCH

The BOSCH WR series instantaneous gas water heaters
are equipped with a high temperature limit switch with a set
point of approximately 90ºC (194ºF). 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 burner.

Outage as the result of high limit operation indicates that
the heater is not functioning properly. The heater should be
checked by a qualified serviceman and the reason for the
malfunction is corrected. To relight the pilot, follow
instructions provided on the unit.

8