Viessmann VITODENS 100-W Installation And Service Instructions Manual page 71

Repairs
(cont.)
3. Lift the front panel from the wall
mounting frame.
Drain boiler on the primary side
Note
For certain repairs the boiler must be
drained on the primary side.
1. Connect the drain hose to valve A
and connect with a drain outlet.
2. Close shut-off valves B and C.
3. Open valve A and drain the boiler
as far as required.
Note
Residual water left in the boiler.
Filling up on the primary side see
page 48.
Troubleshooting
71