Bosch AquaStar 125FX LP Installation And Operating Instructions Manual page 16

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: AquaStars, 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 AquaStar 125FX 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 deriver less than its furl
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 TH E PI LOT
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.
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 AquaStar model 125FX 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, afiow 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 AquaStar 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.
Adjusting screw
L_
Fig. 14 - microswitch adjustment
Pilot does not spark with
water flow
Close water tap
Remove screw cap and
unscrew till sparking starts
Screw in turning one and a
half turns
Pilot always sparks
without water flow
1 Close water tap
2 Screw in adjusting screw
until it stops sparking
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 AquaStar.
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.
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 bleed hole
is a sign that the water valve needs to be replaced
immediately.
10. Poor circuit connections atthe ECO (overheat sensor)
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.
11. Reset electrical power to heater
If resetting the electrical power corrected the symptom then
likely the unit's Safety Spill switch (Flue gas safety device -
#33 on page 20) had tripped from a flue blockage during
the previous usage. Inadequate combustion air to the room
area can also cause the unit to improperly vent. Improper
venting or insufficient combustion air must be corrected.
Consult a licensed professional to inspect the installation.
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