Chapter 6 Control system diagram
SMSO-2-02.06- 15.07.03 211
6.5.24 Discharge valve – “tea”
36V 5V DC
36V S L1, N
Operating condition
When hot water is served, the “tea” outlet valve is open (closed at zero current).
Symptoms
The hot water system outlet valve is not functioning.
Procedure
Process
step
Check Possible cause Remedy
1
Measure voltage at plug X36 1 on
power PCB:
36 V DC ?
Check the voltage supply (see
“Power PCB, control voltage”)
Voltage supply failure / faulty
2
Measure voltage at plug-in con-
tact stud (input) to outlet valve:
36 V DC ?
Plug contacts on power PCB
faulty / oxidised
Cable broken or pulled out of plug
Flat plug not correctly connected
Check / replace plug contacts
Replace cable
Re-connect the flat plug on the
plug-in contact stud
Resistance measurement at outlet valve:
Switch off voltage
Pull out cable from plug-in contact studs
3
Resistance measurement at outlet
valve;
Nominal resistance:
60 Ω ?
Plug in contact studs oxidised
Faulty coil
Replace outlet valve
4
Voltage measurement X36 2,
GND
0 V DC ?
Power transistor does not switch Replace the power PCB
Reconnect the flat plug to the
outlet valve.
Function check: The valve must
open (audible click!)
Cable (or) / power PCB faulty
Mechanical fault on outlet valve
(calcium deposit)
Replace cable / power PCB
Replace outlet valve
NO
YES
NO
YES
NO
ES
NO
ES
NO