Bosch Appliances 125HX NG Water Heater User Manual

12 6 720 606 804 (02.10)
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.
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. Cross over in water lines
To confirm there is no cross-over in the plumbing, shut off
the cold water supply to the AquaStar and open all hot
water faucets. There should not be any water flowing at
any faucets. Water running is a sign of a plumbing cross-
over. Consult your plumber.
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 125HX
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.
The red LED light (located behind the coverplate on the
front panel) flashes when the water flow is not enough.
4. Water inlet filter is clogged
Water flow is restricted, preventing needed flow to activate
heater. Clean water inlet filter screen.
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
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 will need replacing. Any sign of moisture or
corrosion at the joint of the water valve and the gas valve is
a sign that the water valve components need to be serviced
7. 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 and
Flue Gas Safety Device are secure and tighten if necessary.
If the Aquastar is Powervented, check spill switch reset
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 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.
Excessive pressure will lock it up. Locking usually happens
when using propane gas if the gas pressure between the
gas tank and the water heaters gas regulator has not been
reduced. See Page 2 for recommended correct gas
pressure. To unlock a regulator, consult your gas supplier
or call CEC.
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.
4. Pilot electrovalve switch may need to be replaced
(See Fig 13).
Call CEC.
5. Electronic Control Box may need to be replaced
(See Fig 13).
Call CEC.