no reason is identified and after replacement with a new circuit board, the old piece shall be
returned for analysis and verification.
7. Above all, major faulty components of mechanical water heater are heating pipe, temperature
controller or temperature limiter. Thus, repairman shall first exclude the causes of failure one by
one from bus wire to parting line and from simple and complicated position, and finalize the real
cause certainly. Upon identifying the failure, repairman shall replace the faulty piece, power it on
to observe whether it is normal, keep the water heater running for 10-20min and then leave the
site until he guarantees the normal operation of water heater.
(II) Fault analysis and troubleshooting for water leakage
There are many reasons for water leakage. To sum up, there are the following major aspects: water
leakage due to bad connection, water leakage of inner compartment (heating tube), water leakage of
safety valve. During the repair, repairman shall first communicate the rough position of water leakage
with the user and prepare the relative servicing materials and tools. In general, tools and materials as
required shall include: thread seal tape, wrench, sleeve, seal, pressure gauge and corresponding
components, etc.
Repair method:
1. Observe whether there is sign of water leakage from the shell. If there is water stain at the end
cap beyond the scope of repair, it is preliminarily judged as water leakage of inner compartment,
so such heater cannot be repaired; during the warranty period, the water heater shall be replaced
with a new one, free of charge.
2. For water leakage of external joints such as water mixing valve, constant temperature valve and
shower head, repairman shall dismount corresponding components to check whether they are
damaged, replace them with new components or seal them with new seals and thread seal tape;
3. Dismount the overhaul end cap and observe whether there is rusty stain at the sealing position of
heating pipe, which generally results from water leakage of sealing flange of heating pipe and
temperature sensing pipe of heater. The water leakage of sealing flange is mainly caused by the
following:
(1) Abnormal pressure relief of safety valve results in excessive pressure and thus sealing
badness of enamel layer at the compartment mouth;
(2) Looseness due to long-term use of T-shaped screw bolts. For the first cause, the machine
cannot be used any longer, which shall be disposed according to regulations on guarantee
repair. For the second reason, repairman needs to fasten the T-shaped screw bolts. If invalid,
the flange seal shall be replaced. For the water leakage of temperature sensing pipe, there
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