Viessmann VITODENS 050-W Installation And Service Instructions Manual page 72

Troubleshooting
Repairs
(cont.)
3. Check fuse F4.
72
Danger
Incorrect or improperly fitted
fuses can lead to an increased
risk of fire.
■ Insert fuses without using any
force. Position fuses correctly.
■ Only use structurally identical
types with the specified
response characteristics.