Economiser And Extraction - Lennox BCK 020 Installation Operating & Maintenance Manual

ECONOMISER AND EXTRACTION

Economiser
Free cooling can be provided through the use of fresh air where
appropriate rather than cooling excessive amounts of return
air.
The economiser is factory fitted and tested prior to shipment.
It includes two dampers operating from a 24V actuator
Rain hood
It also includes a factory fitted rain hood . Hoods is folded
during transportation to limit risks of damage and must be
unfolded on site as shown below:
VERTICAL FLOW STANDARD INSTALLATION
1
OR
Fresh air
Return air
Supply air
Page 26 - IOM / ROOFTOP BALTIC Series - 0803 - E
Fig. 19
2 2
OR
Fig. 20
1 Supply fan
2 Economiser damper
Extraction
Installed with economiser assembly, the gravity exhaust
dampers relieve the pressure when outside air is introduced
into the system.
When large amount of fresh air is introduced into the system
power exhaust fans can be used to equalise the pressures.
The extraction fan runs when return air dampers are being
closed and supply air blower is in operation. The extraction
fan runs when outdoor air dampers are at least 50% open
(adjustable value) It is overload protected.
NOTE: When horizontal flow configuration is required, the
multidirectional roofcurb will be installed
VERTICAL FLOW WITH EXTRACTION
1
OR
Fresh air
Return air
Exhaust air
Supply air
HORIZONTAL FLOW WITH MULTIDIRECTIONAL
ROOFCURB
1
Fresh air
Return air
Exhaust air
Supply air
2
3
Fig. 21
1 Supply fan
2 Economiser damper
3 Exhaust damper or
Exhaust damper + exhaust fan
2
3
4
Fig. 22
1 Supply fan
2 Economiser damper
3 Exhaust damper or
Exhaust damper + exhaust fan
4 Multidirectional roofcurb