Viessmann BWT 221.A06, Installation And Service Instructions Manual, Page: 76 / 124

76
Sensor Capturing ele-
ment
■ Outside temperature sensor (F0)
■ Flow temperature sensor, cooling circuit (direct heating circuit
A1/HC1 or separate cooling circuit SKK) (F14)
■ Room temperature sensors
Ni 500
■ Buffer temperature sensor (F4)
■ Cylinder temperature sensor (F6)
■ Flow/return temperature sensor, secondary circuit (F8/F9)
■ System flow temperature sensor (F13)
■ Flow temperature sensor, secondary circuit, upstream of the
instantaneous heating water heater
■ Hot gas temperature sensor
Pt 500
Temperature sensors type Ni 500
400
-40 -20 0
Resistance in
Temperature in °C
440
480
520
560
600
20 40 60
640
Temperature sensors type Pt 500
460
20
540
100
Resistance in
Temperature in °C
60 140 180
620
700
780
860
-20
Checking the fuses
For fuse locations, see from page 34:
■ Fuse F1 is located near the luster ter-
minals.
■ Fuse F3 is located on the main PCB.
Fuses F1 and F3:
■ 6.3 A (slow), 250 V~
■ Max. power loss
≤
2.5 W
Danger
Contact with 'live' components
can lead to severe injury from
electric current.
Before working on the equip-
ment, always ensure that
the
power circuit is also at zero
volt.
Troubleshooting
Repairs
(cont.)
5601 574 GB