Viessmann Vitocal 350-A Installation And Service Instructions Manual page 134
Type awh-i, awh-o
air/water heat pump with electric drive, 400 v~
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Also See for Vitocal 350-A:
- Installation and service instructions manual (160 pages) ,
- Operating instructions manual (60 pages) ,
- User manual (236 pages)
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Troubleshooting
Control unit diagnostics
Message
System characteristics Cause
«20 Flow sens. secondary
Operation with tempera-
ture value of return tem-
perature sensor in sec-
ondary circuit, plus 5 K. If
both temperature sen-
sors (secondary flow and
return) are faulty, the
heat pump stops (mes-
sage UA9).
«21 Sec. return sensor
Operation with tempera-
ture value of flow temper-
ature sensor in secon-
dary circuit, minus 5 K. If
both temperature sen-
sors (secondary flow and
return) are faulty, the
heat pump stops (mes-
sage UA9).
«28 Flow sens. secondary
Operation with tempera-
ture value of return tem-
perature sensor in sec-
ondary circuit, plus 5 K. If
both temperature sen-
sors (secondary flow and
return) are faulty, the
heat pump stops (mes-
sage UA9).
«29 Sec. return sensor
Operation with tempera-
ture value of flow temper-
ature sensor in secon-
dary circuit, minus 5 K. If
both temperature sen-
sors (secondary flow and
return) are faulty, the
heat pump stops (mes-
sage UA9).
134
(cont.)
Short circuit, secondary
circuit flow temperature
sensor
Short circuit, secondary
circuit return temperature
sensor
Lead break, secondary
circuit flow temperature
sensor
Break, secondary circuit
return temperature sen-
sor
Measures
Check resistance (Pt 500)
at connections 3X1.20
and 3X2.20; replace sen-
sor if required.
Check resistance (Pt 500)
at connections 3X1.19
and 3X2.19; replace sen-
sor if required.
Check resistance (Pt 500)
at connections 3X1.20
and 3X2.20; replace sen-
sor if required.
Check resistance (Pt 500)
at connections 3X1.19
and 3X2.19; replace sen-
sor if required.
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