6 720 608 036
20
Troubleshooting
read 1.6V AC. If voltage is proper, pilot electro valve is
defective. If voltage is not proper, electronic control box
is defective.
Visit www.boschpro.com
to purchase replacement part,
or call Bosch Water Heating at 866-330-2730 for
replacement part if still under warranty.
6.4 Pilot light, but burners will not
come on.
1. Verify gas type indicated in the rating sticker located
on the cover's right hand side, coincides with the gas
type you are using. NG is a natural gas unit and LP is for
liquid propane (See chapter 2.2).
2. Pilot flame should be blue in color and completely
engulfing the flame sensor. If not, the pilot orifice may be
dirty or clogged. See chapter 5.3 on how to clean the
pilot.
3. Flame sensor not recognizing pilot flame. Verify wire
connection clip on wire from the bottom of the flame
sensor is secure. If flame sensor is fully engulfed by the
pilot flame, it may be dirty. Clean entire surface area of
flame sensor with a pencil eraser.
4. Inspect the water path for obstructions. Make sure all
outlets (i.e. showerheads, faucet aerators and whole
house filters) are clear of debris. Inspect and clean the
water heater's inlet filter screen. See chapter 5.2.
5. Confirm wire connection to the burner electro valve is
secure (see components diagram for location of burner
electro valve). Inspect terminals for corrosion. To clean
terminals, remove the spade connectors and clean with
a pencil eraser.
6. The water valve assembly, which allows gas flow to
the burners, requires periodic maintenance (every 2-5
years depending on water quality and use). Visit
www.boschpro.com
to purchase water valve rebuild kit
to service the water valve.
7.Electric control box, burner electro valve or flame
sensor maybe damaged/defective. Verify adequate
voltage at the spade connection of the burner electro
valve (see components diagram for location of burner
electro valve). After the pilot lights, voltage should read
1.6V AC on the burner electro valve. If voltage is
proper, the burner electro valve is defective. If voltage is
not proper, electronic control box or the flame sensor is
damaged/defective.
Visit www.boschpro.com
to purchase replacement part,
or call Bosch Water Heating at 866-330-2730 for
replacement part if still under warranty.
Fig. 25 Electrical wiring diagram
2 Pilot electrode
3 Flame sensor
18 Microswitch
23 Electronic control box
25 Burner electro valve
28 Pilot electro valve
31 Temperature limiter
32 Flue gas safety device
34 LED indicator main burner operation
35 On/Off button
50 Hydro-generator
111 Overheat limiter
6.5 Main burners go out during hot
water use
1. Hot water flow rate is dropping below required
activation flow rate. Turn temperature adjustment knob
all the way clockwise. Fully open a hot water faucet and
fill a quart container. If the container fills in 30 seconds
or less, the flow rate (1/2 gallon per minute) is sufficient
to activate the water heater. If flow rate is not sufficient,
the water heater's inlet filter should be inspected and
cleaned. See chapter 5.2.
2. Close installer supplied cold water shut off valve (if
none installed, install before proceeding). Open all hot
water taps supplied by the heater. Wait 5 minutes and
check all taps. Any water running is a sign of a plumbing
crossover. Consult local plumber or service person for
help correcting a plumbing crossover.
3. The minimum water pressure for the home should be
30psi or greater. For installation on a private well
system with use of a pressure tank, the lowest pressure
range setting recommended is 30-50 psi (2.07-3.45
bar).
4. Hot water is very hot out of the tap, requiring a lot of
cold water to be added with it in order to attain a
useable hot water temperature. The addition of too
much cold will overpower and slow the flow within the
tankless heater, decreasing it below activation point,
which shuts off the burners. The end result is nothing
but cold water coming out of the outlet. Reduce the
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