Troubleshooting; No Spark At The Pilot - Bosch WR 400-7.K Series Installation & Operation Manual

Maintenance*
If faults occur on the flue gas safety device, proceed as
follows:
- Undo flue gas safety device fixing screw.
- Unplug igniter unit connector.
Replace damaged component with new one and refit using
the reverse of the procedure set out the table above.
Function check*
Flue gas safety device function check:
- Disconnect flue pipe
- Replace with pipe (about 50 cm long) with sealed end
- Fit pipe vertically
- Start up appliance at rated output and set temperature
control to maximum temperature.
Under those conditions, the appliance should shut down after
two minutes. Remove temporary pipe and reconnect flue
pipe.
* This work may only be carried out by an approved engineer.
TROUBLE SHOOTING
Introduction
The Bosch WR400-7.K.. burners are activated by a water
flow valve. Numerous water related problems can cause
this water valve to malfunction such as: Insufficient water
flow volume or pressure to activate the burners at its
minimum flow requirement; Dirt in the water flow valve
causing it malfunction; Sediment built-up in faucet aerators,
or shower heads; Uneven pressures between cold and hot,
(with single lever faucets) Plumbing cross over. These water
flow related problems can cause the heater to deliver less
than its full output, or to fail to ignite or to shut down
completely.
Problems are stated in upper case, bold face. Most common
causes for the problems follow in order of likelihood. The
suggested solutions require that the cover be taken off. To
do this, remove incandescent particle tray, pull off the
temperature adjustment knob and unscrew and remove the
plastic collar. Pull main cover out toward you and lift up and
out.

NO SPARK AT THE PILOT

1. ON/Off switch is not "On" (Position
The On/Off switch is located behind the flipdown cover plate
on the front panel strip. See fig. 9.
2. Water flow is not sufficient to activate heater.
Water flow rate at faucet is below minimum flow needed to
activate heater. When temperature adjustment knob is turned
all the way clockwise, the Bosch WR400-7.K.. 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 seconds. If the
temperature adjustment
counterclockwise, a flow rate of 1. 1 gallons/minute is required
to activate the heater.
Red LED flashes when the water flow is not enough.
3. Water inlet filter is clogged
Water flow is restricted, preventing needed flow to activate
heater. Clean water inlet filter screen.
10
).
knob is turned fully
4. Cross over in water lines
To confirm there is no cross-over in the plumbing, shut off
the cold water supply to the Bosch water heater and open a
hot water faucet. There should not be any water flowing at
that faucet. Water running is a sign of a plumbing cross over.
Consult your plumber.
5. Cold 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.
6. Water valve parts may be dirty or components
damaged
First check that venturi is free of dirt particles. Water valve
and component parts must be 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
may need replacing. Any sign of moisture at the top of the
water valve is a sign that the water valve needs to be serviced
immediately.
7. Loose connection at the ECO or the flue gas safety
device
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 problem at time of initial installation, after
the pipes have been worked on, or after a gas supply line
has been allowed to empty. Bleed the air trapped in the gas
line by turning the hot water faucet on and off until the air
has been cleared from the line.
2. No gas to the Bosch
A. Gas cock on gas line may not be open
B. Gas regulator may be 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 between the gas tank and
the water heater's gas regulator has not been reduced. See
Page 8 for recommended correct gas pressure. To unjam a
regulator, call your gas supplier.
3. Pilot orifice or gas valve is dirty
Clogging of the pilot burner can be caused by dust in the air
or dirt in the gas. The pilot orifice or gas filter may need to be
cleaned or replaced.
5. Pilot electrovalve switch may need to be replaced (See
Fig 16).
Call your service person or call: Canada 1-800-663-8405,
U.S.A. 1.800-824-7337.
6. Electronic Control Box may need to be replaced, (See
Fig 16).
Call your service person or call: Canada 1-800-663-8405,
U.S.A. 1.800-824-7337.
6 720 606 560