Riello DB 3 SM C01 TC A180 FS1 T250 Installation, Use And Maintenance Instructions page 26

2.4 Overall dimensions
FLANGE DIMENSIONS
Air duct connection
D7549
Fig. 4
6
CHAPTER
Fixing to the boiler
3 5 0
4 5 3
D7884
Fig. 5
2
Burner description
20064732
Gas supply
Fig. 6
Fig. 3
6 5 , 5
1 4 5
1 8 5
D7885