Bosch AE115 - Manual (Page 12)

Troubleshooting
WARNING
Always switch off the electricity supply to the unit before you remove the cover.
IMPORTANT:
If you are unable to perform the tasks listed below, or need additional assistance please contact your
original installer/licensed electrician.
Cold water only – Neon light off
Flow rate is too
low Verify the flow rate out of fixture is at or above the minimum activation rate
required for the unit to activate. (Activation rates: AE115 = 0.6 GPM, AE125 = 0.8
GPM).
The water supply
is connected to
the outlet of the
unit Verify plumbing connections are correct (See Diagram 1, Page 4). Reconnect the
water supply to the inlet of the unit (marked blue).
Plumbing
crossover To test for a plumbing crossover, turn off power supply to the heater. 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 a
local plumber or service person for help in correcting a plumbing crossover. To
return the heater to service, reinstall cover, open the inlet water supply to the
heater and open all hot water taps. Let all taps run until there is no air coming out
of the fixtures. Shut off all hot water taps. Turn power supply on to the heater.
Return heater to service. (This procedure will prevent the heating elements from
burning out).
The flow
transducer is not
spinning Turn off the power supply to the heater and remove the cover. Observe if the flow
transducer "spins" when the water is turned on. Please note the flow transducer
spins at a high speed and can appear to be stopped when actually spinning. It is
recommended to observe the flow transducer without water flowing, then turn on a
hot water tap while observing the flow transducer. If the flow transducer is not
spinning, remove and flush
flow transducer, noting the Do's and Dont's on Page 11.
See the technical support section of www.boschhotwater.com for more detailed
instruction on removing the flow transducer.
One or more of the
heating module
thermal cut-outs
has tripped Turn off the power to the heater, remove th e cover and locate thermal cutouts on
the top of each heating module. Try resetting each cutout by pushing the reset
button located in the center of the cutout. Determine and fix the cause of the
overheating. Obstructions in the water path can restrict t he flow of water through
the heater causing it to overheat. Verify the heater’s inlet filter screen and all
outlets served by the heater are clear of debris. Ensure the heater is not being fed
preheated water. This water heater is designed for a cold wat er supply only. If
thermal cut out does not reset, check for continuity through each cutout (less than
0.5 Ohms). If any cutout reads more than 0.5 Ohms or open, then it may be
defective and should be replaced.
No electricity at
the heater or one
of the supplies has
failed Have a licensed electrician verify proper wiring and adequate voltage on the
terminal block inside the water heater. See the “Electrical connections” section on
Page 5 of this manual.
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