Viessmann Vitovalor 300-P Installation And Service Instructions For Contractors page 124

Troubleshooting
Repairs (gas condensing module)
Draining gas condensing module on the heating water side
A
Fig. 92
1. Shut off the connections on the heating water side.
2. Attach a hose to drain valve
drain.
Draining the heating water buffer cylinder
Fig. 93
124
(cont.)
and connect to a
A
3. Open drain valve .
A
1. Check that the fuel cell module is switched off.
2. Connect the hose to the drain valve and route it
into a suitable container or drain outlet.
3. Turn the lever on the drain valve to position
Note
This will not drain the process circuit of the fuel cell
module. See page 81.
.
C