Buderus Logano plus GB312, Installation And Service Instructions Manual

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10
Troubleshooting
Logano plus GB312 – 6 720 806 273 (2013/01) 53
10.2.2 Fault displays
Type
1)
Display code Fault code Cause Description Testing sequence/
Cause Measure
K 2E 207 The water pressure is < 8.7
psi (0.6 bar). - Is the pressure in the
heating system at least
14.5 psi (1 bar). Adjust operating
pressure.
K 2U 565 Difference between supply
and return temperature too
great.
(>72 °F; >40 K)
Heat exchanger cut-out
due to excessive
temperature spread. System configuration
problems. Check system
configuration.
V 2U 575 Boiler sensor/ISTB sensor. The maximum
permissible temperature
at the ISTB has been
reached. Check water flow. Check water flow.
Check orientation of
check valve (direction of
flow).
Check boiler sensor/
STB.
V 3C 537 No speed signal. The SAFe is not receiving
a speed signal even
though the fan is
supposed to be running. Check connecting cables
between SAFe and fan for
poor contact, breaks and
damage.
Check connectors on
SAFe and fan.
Establish good electrical
contact. Replace cable if
necessary.
If fan has power (but is
not running) replace fan.
If fan has no power,
replace the SAFe
V 3C 538 Fan speed too slow. The actual speed
detected is slower than
the set speed. Dirt in fan.
Fan defective.
Clean fan if necessary.
Replace fan.
V 3C 540 Fan speed too fast. The actual speed
detected is faster than
the set speed. Check PWM signal/SAFe
connecting cable for poor
contact, breaks and
damage.
Check connectors for
damage.
Establish good electrical
contact. Replace cable if
necessary.
Replace fan.
V 4A 520 Boiler safety temperature
limiter (STB). The supply temperature
has reached 200 °F
(93 °C) (cut-out
temperature of boiler
temperature limiter). Fault can only occur as a
result of faults in the
system configuration
(e.g. only in 2-boiler
systems). Check system
configuration. Check
orientation of check
valve (direction of flow).
V 4U 521 Temperature difference at
twin boiler sensor too great. Temperature difference
between supply
temperature sensors 1
and 2 too great
(deviation of > 9 °F/2 s;
5 K/2 s). Check connectors on
boiler temperature sensor
and SAFe for dirt/
damage.
Check boiler temperature
sensor resistance against
sensor characteristic/
visually check plug on
temperature sensor.
Check the voltage at the
boiler temperature sensor
against the table (SAFe
document).
Clean contacts/replace
connecting cable if
necessary.
If there are
discrepancies in the
sensor readings or the
connector is defective,
the temperature sensor
must be replaced.
Replace SAFe if there
are discrepancies.
Table 23 Fault displays
1) V = interlocking; B = inhibiting; BC = operating code