128
Fault mes-
sage
Cause Remedy Re-
set-
ting
"270: Exc
temp diff h'
exch"
Excessive temperature dif-
ferential between the heating
water flow and return.
Check the system pressure.
Vent the heating system.
Check whether there is any
throughput (code 8366 in di-
agnostics heat generation)
Check function of the circula-
tion pump.
Check function of 3-way
diverter valve.
Check temperature sensors
and flow sensor.
AR
"274: Zero
flow protec-
tion"
Flow rate too low after filling. UR
"275: Zero
flow aft dea-
er"
Flow rate too low after vent-
ing.
UR
"276: Zero
flow"
Inadequate flow rate cap-
tured in heating mode.
AR
"278: Max
temp rise"
Max flow temperature in-
crease exceeded.
AR
"280: Inner
iron over-
temp"
Generator base excess tem-
perature. Thermostat has re-
sponded.
Check connecting cables be-
tween Stirling engine and
control unit (cables to plug
X205).
Check temperature at bottom
of Stirling engine: max.
100 °C.
Check whether there is a
min. flow rate of 240 l/h (code
8366 in diagnostics heat gen-
eration).
Notify Viessmann Technical
Service.
AR
"281: Dyn
absorber
tripped"
Dynamic absorber overtravel
switch actuated.
Check plug-in connection
X205, connecting cables and
plugs to overtravel switches
at the bottom of the Stirling
engine (see page 152).
Check spring length; adjust if
necessary (see page 77).
Notify Viessmann Technical
Service if no fault can be dis-
covered or if unusual noises
can be heard.
SR
Troubleshooting
Fault messages
(cont.)
5618 294 GB
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