Riello DB4 SE C03 A180 FS2 Installation, Use And Maintenance Instructions page 26

2.4 Overall dimensions
20060864
FLANGE DIMENSIONS
Air duct connection
D7549
6
1530
705
158
D7884
Fig. 4
2
CHAPTER
521
372
Fixing to the boiler
3 5 0
4 5 3
Fig. 5
Burner description
666
391 275
Gas supply
6 5 , 5
1 4 5
1 8 5
D7885
Fig. 6