Understanding Air Flow Through Ventilation

These illustrations are intended to indicate the wrong and the right way to ensure that air flows through the ventilated rooms to cause the desired effect — fresh clean dry air to every part of each room. In the illustrations — for simplicity we may have shown inlet and outlet penetrations through the roof of the home — this is not intended to be that way for every home — Supply and Exhaust air discharge and sources can be through the roof, through a gable end, or through the soffit, as is appropriate for your home.

Also, we have deliberately not shown air filters in these sketches — if you think you need an air filter see Air Filters Explained


Air supply and exhaust too close together.

Warm air is pushed down by the fresh supply air flow but then immediately convects upwards and is collected and exhausted to the outside up by the Exhaust Fan.
Fresh warmed air does not circulate throughout the room. Note the ((( “Stale Air” area.

Good air flow but wrong direction

Warm fresh air supply to the kitchen flows to the living area and carries kitchen odours into the living room.
The Exhaust vent in the living room “pulls” air from the kitchen, with kitchen odours and humidity, into other areas of the house.

Ideal Air Distribution

Fresh, warm, dry Outdoor Air is supplied to the living room, exhausted from the kitchen.
Air flows from Supply, in living room, to Exhaust, in the kitchen – kitchen odours and food smells from the dining room are all gently driven towards the kitchen Exhaust vent.
The rooms between literally become an “air duct” which is permanently ventilated with warmed, dried, fresh Outdoor Air.

An Ideal Alternative

Supplies to bedroom and living room on opposite sides of the house with Exhaust in the hallway between rooms.

Warmed, dried, fresh outside air is delivered to the perimeter of the living and bed rooms.
The rooms literally become a duct for this air, which flows from the outside walls (opposite the doors) to a single Exhaust grille located in the hallway.


0800 DRY AIR  (0800 379 247) 

Email: info@avonelectric.co.nz

Products are New Zealand made by Avon Electric Ltd.


Avon Electric Ltd
25 Taurus Place, Bromley
P.O Box 19748, Christchurch 8030 
Ph: 03 381-5595  - Fax: 03 381-5596