Bosch UT-L 1 Technical Manual page 68

68 | Fitting
Sizing ventilation and extract air apertures
• Size ventilation and extract air apertures to obtain a
pressure of ± 0 mbar in the boiler installation room.
• If the combustion air is routed via air inlet channels to
the burner, ensure an optimised flow path and
adequate sizing with regard to the pressure loss.
• The side ratio of the aperture must not be more than
1:2.
• Extract air cross-sections correspond to 60 % of the
ventilation air cross-sections.
The calculation formulae below are a non-binding
recommendation. It is essential that the system installer
seeks the agreement of the responsible approval or
building regulations body. Take into account additional
consumers of ventilation air (e.g. compressors) when
sizing.
For outputs ...
≤ 2000 kW
> 2000, ≤ 20000 kW
> 20000 kW
Table 30 Calculating free ventilation air cross-sections
1) A = free cross-section (net) in cm
6 720 807 794 (2013/04)
... the following calculation
applies for the free
ventilation air cross-
1)
section
A = 300 + [(Q – 50) × 2.5]
A = 5175 + [(Q –
2000) × 1.75]
A = 36675 + [(Q –
2000) × 0.88]
2
, Q = output in kW
UNIMAT