Bosch GWH 425 EF, Руководство пользователя

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3. 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 model 425 EF 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 knob is turned fully
counterclockwise, a flow rate of 1.1 gallons/minute is required
to activate the heater.
4. Bad fuse
Check the viability of the fuse (see Fig 9 (#9) for location
of fuse). Replace if necessary.
5. Water inlet filter is clogged
Water flow is restricted, preventing flow needed to activate
heater. Clean water inlet filter screen.
6. Cross over in water lines
To confirm there is no cross-over in the plumbing, shut off
the cold water supply to the 425 EF 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.
7. Microswitch needs to be adjusted or replaced.
If you do not hear a click when a tap is opened, the
microswitch needs to be adjusted. See Fig. 15 (#11) for
location and see Fig. 14 for adjustment. The microswitch
may need to be replaced.
G871_212
Adjusting screw
Fig. 14 - microswitch adjustment
Main Burner Flames: 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, or a blockage on the heat exchangers fins. If some
burners have yellow flames while others have good 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.
Mineral Scale Build-up: 425 EF, when operated at lower
temperature settings, do not accumulate mineral buildup. 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.
Consult your dealer or service person.
TROUBLE SHOOTING
(see maintenance table)
Introduction
The 425 EF pilot and burners are ignited by a water flow
valve. Numerous water related problems 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-up in faucet aerators, or shower heads;
Uneven pressures between cold and hot with single lever
faucets; Plumbing cross overs. 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, pull off the temperature knob and unscrew and
remove the temperature knob 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. 10.
2. Bad electrical connections.
Be certain that all electrical connections are clean, tight,
and free of any moisture.
Fig. 13 - Pilot burner with pilot orifice
PILOT ORIFICE
Pilot does not spark with
water flow Pilot always sparks
without water flow
1 Close water tap 1 Close water tap
2 Remove screw cap and
unscrew till sparking starts
2 Screw in adjusting screw
until it stops sparking
3 Screw in turning one and a
half turns
3 Continue to screw in
turning one and a half
turns more
8. Cold incoming water connection made to wrong side
of heater
Make sure cold water inlet connection is on the right side
when you are facing the 425 EF.
9. 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.