Viessmann VITOCAL 300-G Installation And Service Instructions Manual page 138

Troubleshooting
Messages
(cont.)
Message
System characteristics Cause
AF Cylinder prim pump
138
■ Circulation pump for
cylinder heating faulty
■ Circulation volume in
primary store system
too low; cylinder pri-
mary pump or two-way
valve on primary store
system faulty.
Measures
■ Check power supply,
connecting cable and
plug for the instantane-
ous heating water
heater.
■ Test instantaneous
heating water heater
control signal at con-
nections 211.3 (stage 1)
and 224.4 (stage 2);
check high limit safety
cut-out and reset if
required; check instan-
taneous heating water
heater.
Installation
instructions,
instantaneous
heating water
heater
■ Circulation pump for
cylinder heating:
Test voltage at connec-
tion 211.4 and check
pump mechanically;
replace if required.
■ Cylinder primary pump/
two-way valve:
Test voltage at connec-
tion 224.6 and check
pump/valve mechani-
cally; replace if
required.