Bosch 125FX LP - Manual (Page 17)

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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 at the 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 22) 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.
SPARKS APPEAR AT PILOT WHEN HOT WATER TAP IS
TURNED ON, BUT PILOT AND BURNERS WILL NOT IGNITE
1. Air in the Gas Line
Note: Normally this is a problem only at the time of initial
installation, after the pipes have been worked on, or after a
propane tank has been allowed to empty, or after the heater
has been shut down for a long time.
Bleed all 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 AquaStar
A. Gas cock on gas line may not be open
B. Gas regulator may be shut or damaged. Replace or unlock
the regulator. Note: The regulator furnished with the heater
is exclusively designed for low gas pressure (less than ½
psig). Excessive pressure will lock it up. Locking usually
happens when the gas pressure between the gas tank and
the water heater’s gas regulator has not been properly
regulated. See Page 2 for recommended correct gas
pressure. To unlock a regulator, consult your gas supplier or
a gas technician.
3. Pilot orifice clogged 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. See Fig. 13.
4. Water valve assembly needs to be checked
If the pilot orifice is clean, the water valve assembly should
be checked. The adjustment screw on the water valve micro-
switch may not be tight enough (fig. 14). Remove central
cap beneath micro-switch assembly, carefully loosen the
adjustment screw until the pilot light ignites. At that point
retighten the screw one and a half turns. See Fig 14.
5. Pilot electrovalve switch may need to be replaced (see
fig 9).
Measure millivoltage at pilot electrovalve (see Fig 9).
6. Control Box may need to be replaced (see fig 9).
Check wire connections and test operation of control box
(see Fig 9).
PILOT SPARKS CONTINUOUSLY WITH NO WATER
RUNNING
1. Microswitch needs adjustment
If no water is running, but pilot electrode continuously sparks,
the microswitch screw to the water valve needs adjustment.
See Figure 14.
PILOT LIGHTS BUT BURNERS WILL NOT COME ON
1. Confirm the flame sensor is in its proper position. see
Figure 12.
2. Poor circuit connections at the flue gas safety device
The burners will not come on if the powered fan exhaust is
not working. Check that the unit is plugged in and that the
sensors for the flue gases are secure.
3. Confirm the ECO connections are secure.
4. The Control Box may need to be replaced
(see Fig. 9).
Check wire connections and test operation of control box
(see Fig 9).
5. Burner electrovalve switch may need to be replaced
(see Fig. 9).
MAIN BURNERS GO OUT DURING HOT WATER USE
1. Deficient exhaustion of flue gases
Check that vent is correct and clear of any obstructions,
that sensors for flue gases are secure and that electrical
connection has been made. If the heater will not come back
on, it will be necessary to turn the electrical supply to the
heater off and then on again.
2. Flow rate diminished below activation rate
Be certain that water flow is not less than required amount
to activate heater.
3. Unbalanced pressure in waterlines
The added restriction caused by the Aquastar in the hot
water system can result in uneven pressures between the
cold and the hot. In such cases when mixing cold water at
the tap, the lower hot water pressure may be overpowered
by a much higher cold water pressure, which may cause the
Aquastar burners to shut down (deactivate). Make sure faucet
aerators or shower heads are free of minerals. Do not add
any flow restrictor to the shower head.
Typically this deactivation symptom is a result of the hot
water being too hot to use comfortably. Warm inlet water
generally causes this. Lowering the control knob setting
and/or reducing the inlet gas supply to the heater should
correct this deactivation symptom.
4. ECO (overheat sensor) tripped due to overheating
Do not feed preheated water to this water heater.
5. Minimum inlet pressure on well pressure tank is
inadequate
Check the inlet water pressure. For installation on a private
well system with the use of a pressure tank, the lowest
pressure range setting recommended is 30-50 psi (2.07-
3.45 bar).