Takagi T-K3 Service Manual page 33

Nature of Fault
・ The hot water turns
cold and stays cold
・ The fan motor is still
spinning after
operation has
stopped
・ Abnormal sounds
come from the unit
Nature of
Fault
-Fault of gas solenoid valves (SV
during stage changes
-Fault of flow adjustment valve
・ Fluctuation
of hot water
1 Check whether the filter in cold water inlet is cleaned.
temperature.
2 Check whether the gas supply pressure is adequate.
Check for cross connections between cold water lines and hot
3
water lines.
4 Fault of PCB in the T-K3.
No voltage to gas solenoid valve (SV
①
Normal: DC78 ～ 100V between COM (blue) & #53 (orange)
No voltage to gas solenoid valve (SV
②
Normal: DC78 ～ 100V between COM (blue) & #73 (red)
5 Gas solenoid valve (SV
Disconnected wiring to gas solenoid valve (SV
①
Normal: 1.3 ～ 1.9k Ω between COM (blue) & #53 (orange)
Disconnected wiring to gas solenoid valve (SV
②
Normal: 0.9 ～ 1.7k Ω between COM (blue) & #73 (red)
6 PCB fault
No voltage to flow adjustment valve
①
Normal: DC7 ～ 16V between (red-black)
7 Flow adjustment valve fault
Normal: 0.09 ～ 0.2k Ω between (red-black)
1 Check whether the flow rate enough to keep the T-K3
running.
2
Check if there is a recirculation system installed and check
also if the recirc ulation line has enough check valves.
3 Check that the filter on the cold water inlet is clean.
4
Check that the fixtures are free from debris and obstructions.
1 This is normal. After operation has stopped, the fan
motor keeps its running from 5 to 50 sec. in order to re-
ignite quickly, as well as purge all the exhaust gas out
of the flue.
1 Check if there is any blockage on the air inlet of the
unit.
2 Check if there is any blockage of the exhaust pipe.
3 Check the manifold pressure in the unit.
Malfunction description
Diagnosis
) fault
2
33
Diagnosis
Cancellation method
& SV )
3
2
).
2
).
3
)
2
)
3
CONFIDENTIAL
T-K3 Servi c e Manual
Ver. 1.05
Checkpoint
Checkpoint
C
C
J1
J1