Viessmann VITOCAL 350-A, Installation And Service Instructions Manual

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140
Message
System characteristics Cause Measures
«
7A Room sensor HC3
■ No frost protection
mode via room temper-
ature sensor
■ No room temperature
hook-up
■ No room temperature
control
Break, room temperature
sensor heating cir-
cuit M3 Check remote control
sensor and replace if
required (see Vitotrol
service instructions).
«
92 Collector sensor
Short circuit, Vitosolic
collector temperature
sensor Check sensor and replace
if required (see Vitosolic
installation and service
instructions).
«
93 Solar return sensor
Short circuit, Vitosolic
return temperature sen-
sor Check sensor and replace
if required (see Vitosolic
installation and service
instructions).
«
9A Collector sensor
Break, Vitosolic collector
temperature sensor Check sensor and replace
if required (see Vitosolic
installation and service
instructions).
«
9B Solar return sensor
Break, Vitosolic return
temperature sensor Check sensor and replace
if required (see Vitosolic
installation and service
instructions).
A4 Check valve
Solar check valve stuck
or faulty Inspect check valve and
replace if required (see
Vitosolic installation and
service instructions).
«
A6 Secondary pump
No flow in secondary cir-
cuit (secondary circuit
pump stopped) Test voltage at connection
2X8.7 and check secon-
dary pump mechanically;
replace if required.
Troubleshooting
Control unit diagnostics
(cont.)
5414 828 GB