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8
5. Cross Flow Ventilation
Cross flow ventilation ensures that there is suicient fresh air entering the space where
your refrigerator is operating and that the stale hot air is extracted from the area. Fresh air
is supplied to the space, through openings or vents, preferable from the outside to reduce
the risk of hot air recycling through the condenser. The used hot air is extracted from the
space either through natural convection or the use of an extraction fan. This results in
cross flow ventilation.
Natural Convection
Warm air naturally will rise up. If you have vents of equal size at the top and bottom of
your space, the warm air will naturally rise up and out the top vent which draws cooler air
from outside through the bottom vent, this method naturally replaces the hot stale air with
fresh cool air automatically. Cross flow, in one vent and out the other.
Extraction Fan
If your space is an odd size, shape or extraction has to go through cupboards or voids, then
extraction fans are needed to create the flow of air from your cool air intake vent to your
exhaust vent.
Fan Selection
Fan selection is a very important part of this process, the volume of the area where the
fridge is kept, needs to be worked out. And the fan selected needs to be able to remove
this volume, this is measured in litres per minute (Ltr/Min) or cubic feet per minute (CFM).
The other is static pressure of a fan, and this is its ability to push or pull air through
resistance. Eg. Through a vent, the fins on the condenser and around corners and
obstructions.
As a general rule of thumb:
• 120mm DC fan (minimum).
• 7 blade and aggressive curved blades (air flow and static pressure).
• If noise is going to be an issue, 40dB-A and under is recommended.
Vent Sizing
The bigger the better. For upright fridges we recommend the supply vent and exhaust vent
be 480mm x 250mm, this allows adequate ventilation and replenishment of hot stale air
with fresh cooler air.
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