When the outdoor air inlet opens and the return air flow is closed proportionally, the pressure inside the
building increases. When the pressure is greater than atmospheric pressure, the damper is opened to
release any excess pressure directly outdoors.
Where the return duct connection to the unit is at the bottom, the barometric damper assembly and rain
protection are installed on the side of the unit.
Where the return duct connection to the unit is on the side, the barometric damper assembly and rain
protection are installed as close to the unit as possible, directly on the front of the return duct.
The barometric damper is supplied installed on the side panel of the unit.
The rain protection is supplied separately, for on-site installation.
B
A
A
Rainhood Economiser
B
Rainhood Barometric damper or Exhaust fan
Model
L
100 / 125
1805
150 / 175
2255
2.6 Exhaust fan
This is the most suitable extraction system for installations using an economiser or motorised damper,
where the air return is ducted and planned air exhaust is above 25% of the total supply air flow. The
system is formed of a group of axial fans (two units in the models 100 / 125 and three units in the models
150 / 175), an excess pressure damper and the rain protection, which is the same as the barometric
damper. To consult the dimensions, see section
Barometric excess pressure damper
, see on page 44.
Options and accessories
2
Exhaust fan
2.6
45