Section 2 – Description of the Device
Fig. 2.1 Supply-air/extract-air system with heat recovery
1 Fresh air*
6 Air diffuser
NOTE!
* Outside installation points for the Fresh Air
intake (1) and the Exhaust Air outlet (4) MUST be
sufficiently far enough apart to prevent the
exhaust air being drawn into the property through
the Fresh air duct. (No “re-circulation”).
2 Supply air
7 Air transfer opening
3 Extract air
A Supply-air area
4 Exhaust air*
B Extract-air area
5 Ventilation unit
C Air transfer area
Halls and corridors normally act as transfer areas in which the air from the supply areas flows into the extract
areas. Undercut doors and air transfer grilles are used so that the air flow between rooms is not restricted.
Where fitted, a radial air-duct system with direct pipe routes between air diffusers and supply air/extract air
valves:
• Simplifies the balancing of volume flow rates and pressures
• Prevents sound transmitting from adjacent rooms
• Makes cleaning easier, due to direct pipe routes
2.4 System Design
The ventilation system must be properly designed by a qualified ventilation engineer so that it meets the
requirements of the building.
The plan will determine :
• The location of the Supply air inlets (Low pollution: Usually living rooms, bedrooms, recreation rooms,
offices, etc)
• The location of the Extract air outlets (Higher pollution: Usually bathrooms, toilets, kitchens, utility rooms,
etc)
• The requirement for any undercut doors and air transfer grilles. (Usually Halls and corridors, etc)
• The overall required Supply flow rate
• The overall required Extract flow rate
• Supply and Extract flow rates into individual rooms
(Devices such as grilles or diffuser or dampers can be used to set individual room rates)
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