Buderus Logano plus GB402 Installation And Maintenance Instructions Manual page 46

10 Troubleshooting
Display
1)
Type code Fault code
V 4U 521
V 4U 522
V 4Y 523
V 4U 524
V 4A 575
B 5L 542
Tab. 22 Fault displays
1) V = locking; B = blocking
46
Cause Description
Excessive sensor Excessive temperature
differential at the differential between
boiler sensor temperature sensors
between 1 and 2 (deviation
temperature > 5 K/2s).
sensors 1 and 2.
Boiler sensor A temperature sensor
short circuit fault was detected in
between test mode.
temperature
sensors 1 and 2.
Boiler Temperature too low at
temperature the boiler temperature
sensor lead sensor (< -5 °C)
break.
Boiler sensor The boiler sensor
short circuit. detected an
excessively high
temperature
(> 130 °C).
Intelligent high The boiler flow
limit safety cut- temperature has
out responds. reached its maximum
permissible level.
Incomplete The MC10 generates
communication this fault if not all
with the SAFe. required data is
supplied by the SAFe.
Test procedure/cause
Check that the "Reset" button
illuminates on the SAFe.
Check that the check valve on the
cylinder primary pump is closed.
Check whether the flow and
return have been connected
correctly.
Check whether the plug-in
connection on the boiler sensor
and on the SAFe are
contaminated or damaged.
Check the resistances at the
boiler sensor according to table or
visually inspect the plug at the
temperature sensor.
Check the voltage values on the
boiler sensor according to table.
Check the sensor lead.
Check the plug-in connection.
Check sensor values according to
table.
Check the voltage at the
temperature sensor according to
table.
Check the sensor lead.
Check the plug-in connection.
Check sensor values according to
table.
Check the voltage at the
temperature sensor according to
table (SAFe documentation).
Check the sensor lead.
Check the plug-in connection.
Check sensor values according to
table.
Check the voltage at the
temperature sensor according to
table (SAFe documentation).
Hi limit safety cut-out has
responded.
Check the cabling between the
SAFe and the MC10.
Logano plus GB402 – 6 720 804 428 (2012/09)
Correction
Press "Reset" on the SAFe.
Close the check valve if it is still
open.
If flow and return have been
swapped, connect flow and
return correctly.
If required, clean or replace the
plug-in connections.
Replace the boiler sensor if the
sensor values deviate from the
stated values, or if the plug is
faulty.
Replace the SAFe if there are
deviations.
Replace in case of damage.
Clean or replace if
contaminated.
Refit plug it is found to be
loose.
Replace the temperature
sensor in case of deviations.
Replace the SAFe in case of
deviations.
Replace in case of damage.
Clean or replace if
contaminated.
Replace in case of damage.
Refit plug it is found to be
loose.
Replace the temperature
sensor in case of deviations.
Replace the SAFe in case of
deviations.
Replace in case of damage.
Clean or replace if
contaminated.
Replace in case of damage.
Refit plug it is found to be
loose.
Replace the temperature
sensor in case of deviations.
Replace the SAFe in case of
deviations.
Check gas train.
(Does the flame extinguish
after a control shutdown?)
Replace the SAFe if the
connections are OK.