Riello RDB4 Installation, Use And Maintenance Instructions page 42

The combustion air supply is through a flexible or rigid pipe con-
nected to the air intake.
Consequently, you must comply with the following requirements
and instructions:
➤ The combustion air intake tube must be:
- fastened securely to the burner;
- made of a suitable material, with temperature characteris-
tics in the range - 30 °C to 80 °C;
- in compliance with all requirements of applicable regula-
tions in force in the country of destination.
➤ The intake-tube / burner system must not allow a loss of
3
over 2 m /h at 0.5 mbar:
for instance, the above requirements will be met if you use flues
for pressure exhaust of flue gases (the condensation kind).
➤ Make sure the air intake tube's inlet is positioned so that it is
not likely to be obstructed by foreign matter and, where nec-
essary, use suitable screens.
➤ The inside diameter of the hose must be at least 80 mm.
➤ The intake tube can be up to 6 metres in length.
Length is reduced if there are bends in the intake
section.
For instance, using a tube with a smooth inside
WARNING
surface, you must allow for the following losses:
– for each 45° bend, tube length is reduced by
0.5 m;
– for each 90° bend, tube length is reduced by
0.8 m.
NOTE:
Burner installation must comply with one of the installations
illustrated in the figures below.
➤ Under no circumstances should the air's
entry in the hose intake area be obstructed.
➤ The hose must not be blocked in any way or
feature a shutting device (valves, membranes
WARNING
etc.).
➤ Coaxial tubes must not be installed for any
reason.
20071933
Installation
S7876
S7853
12 GB
S7851
Fig. 10
Fig. 11
Fig. 12