Responsible Refrigeration
BARNEY RICHARDSON
Barney Richardson is the director of South African Refrigeration and Air
Conditioning Contractors Association (SARACCA) and sits on various other
boards within the HVAC industry, including the South African Qualifications
and Certifications Committee for Gas (SAQCC) Gas.
THE TRUTH ABOUT INDOOR AC
By Barney Richardson
This month I deviate again from refrigeration requirements to compliance
requirements for meeting skills training and registration with SAQCC Gas.
T
o follow on from last month’s discussion I recently read an
article regarding a complaint that air conditioning causes
illness through colds and hay fever. One point made was that
an air conditioner either through the wall or window type, or
a split unit does not bring fresh outside air into the space. The
popular choice of air conditioner these days is a midwall split air
conditioning unit for many applications.
Many people falsely believe that air conditioners bring fresh
outside air into the office space or house. For some people with
allergies this is of concern when there is high incidence of pollen
through spring and summer. There are a lot of pollutants in the
air from outside and also inside from furnishings such as carpets,
pets and paint. The fact is that air conditioning units do not bring
fresh air in from outside.
In hot humid weather the air conditioner is switched on and
then the windows of the office or home are tightly shut to keep
the cool air in and not to waste cooling energy. The penalty of that
is so that no fresh air can come into the space.
If you inspect your air conditioner, you will see that there is an
inside unit, the evaporator and an outside condensing unit. These
are connected by copper refrigeration pipes with a refrigerant
flowing between the two units, either as a liquid going to the
indoor unit or suction gas going back to the outdoor unit. The air
flowing through the outside unit is just outside air, the air blowing
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from the indoor unit is recirculated air inside the room. The
indoor unit has a return air intake grille which includes a filter to
collect dust. No fresh outside air is introduced through a split air
conditioner unit.
The outdoor unit has a fan to push air across the condenser
coil, taking heat out of the refrigerant and cooling it down to
be recirculated to the indoor unit in liquid form. If indoor air
quality is a major concern, additional fresh air ventilation steps
must be taken to ensure volatiles and pollutants are not re-
recirculated. A dedicated ventilation system for a space may
be required. A purpose-designed fresh air ventilation system
to supply fresh filtered air to the office space and to displace
stale air will ensure the quality of indoor air. Filtered ventilation
is used to remove the pollutants and odours, dust, bacteria
and carbon dioxide. To avoid indoor air stagnation requires the
continuous circulation of fresh air through a correctly sized
ventilation system. It may not always be possible to have a
dedicated ventilation system for a home but leaving one or
two windows slightly open will create circulation and dilute
stale indoor air.
To repeat last month’s advice for ventilation be aware of
minimum fresh air requirements. A good rule of thumb is 6ℓ/s
to 12ℓ/s per person dependent on the activities in the space or
alternatively 1.2ℓ/s /m². RACA
RACA Journal I April 2020
65