Opop H 635 Manual page 16

Underburning / through-burning
flap in the underburning position
The underburning method is used for the following fuel types:
- Lignite
- Anthracite
- Small wooden waste
Close the firing flap immediately after a proper burning is obtained and set an adequate volume of the secondary
air.
Note:
This combustion method offers the best economy and cleanness, since it ensures perfect and practically smoke-
free burning of fuel and thus its maximum utilization.
Hot Water Boiler Manual – Models H 635, H 650
Fig. 6: Boiler section – fuel underburning
16
Firing flap in the
operating position
(closed)
Secondary air inlet
open slightly