Weh - Water Electric Heater; Dhwt - Domestic Hot Water Tank - Hitachi YUTAKI Series Service Manual

7.6.2. WEH - Water Electric Heater

observed failure
Electric power supply
problems in WEH
Problems in Water Circuit
due to low Water Pressure or
no Water in Water Circuit
Problems in Water Circuit
due to excesive Water
Temperature in Water Circuit

7.6.3. dHWT - domestic Hot Water Tank

Troubleshooting-DHWT-200/300E/S-2,5H1E
observed failure
"Electric power supply
problems in DHWT"
"Problems in Water
Circuit due to low Water
Pressure or no Water in
Water Circuit"
"Problems in Water
Circuit due to excesive
Water Temperature in
Water Circuit"
SMGB0066 rev.0 - 12/2009
228
Troubleshooting of accessories
Cause
Control signals from Systems Controls
miss-connected or wrongly connected
WEH has no Power
Terminals L1~L3 have no voltage
(440V/230V)
LWPS is OFF
[Water Pressure < 0,1 MPa]
Thermostat Cut-Out activated
[Excesive water temperature (<85ºC)]
Cause
"Control signals from Systems Controls
miss-connected or wrongly connected"
"DHWT has no Power Terminals L~N
have no voltage (230V)"
[Water Pressure < 0,1 MPa]
"Thermostat Cut-Out activated
[Excesive water temperature (<90ºC)]"
Check item
Check connections between System
Controller and WEH
Check Voltage (230V) between
terminals 8/9 and 8/7 in WEH and also
in System Controller
Check Voltage (230V) between
Terminals A1 & A2 in Contactor Coils
of WEH
ELB, CB or Fuse protecting WEH are
activated. There is some short-circuit,
wrong connection or any earth leak
Check possible miss connections in
WEH power circuit
Check Electric Resistances:
26,5 Ohms (5% Tolerance)
Check Water Pressure
(must be >0,1MPa)
Check if Water Circuit is locked
Check if there is Water leaks
Check Water Temperature and
Thermostat state
Check item
"Check connections between System
Controller and DHWT"
"Check Voltage (230V) between terminals
N/3 and N/4 in DHWT"
Check Voltage (230V) between Terminals 7
& 8 in Relay coils of DHWT
"ELB, CB or Fuse protecting DHWT are
activated.
There is some short-circuit, wrong
connection or any earth leak"
Check possible miss connections in DHWT
power circuit
"Check Electric Resistances:
17,7 Ohms (5% Tolerance)"
"Check Water Pressure
(must be >0,1MPa)"
Check if Water Circuit is locked
Check if there is Water leaks
"Check Water Temperature and Thermostat
state"
Troubleshooting
Service Manual
Action
Terminals 7, 8, 9 from System Controller
connected to Terminals 7, 8, 9 WEH
respectively
Check Power Supply in System
Controller
Repair connections if required
Check cable connections in WEH power
circuit. Repair circuit and replace Fuse
or Switch ON ELB/CB
Check cable connections in WEH power
circuit. Repair circuit.
Replace Resistances if required
Fill Water Circuit with enough pressure
(< 0.1MPa)
Check Valves and Water Circuit to
ensure water circulation
Check Water circuit and repair leaks
if exist
Push reset button for thermostat re-start
Action
Terminals 11, 12 from System Controller
connected to Terminals 3, 4 DHWT
respectively
"Check Power Supply in System
Controller"
Repair connections if required
"Check cable connections in DHWT power
circuit. Repair circuit and replace Fuse or
Switch ON ELB/CB"
"Check cable connections in DHWT power
circuit. Repair circuit."
Replace Resistances if required
Fill Water Circuit with enough pressure (<
0.1MPa)
Check Valves and Water Circuit to ensure
water circulation
"Check Water circuit and repair leaks if
exist"
"Push reset button for thermostat re-start"