What is the capacity of an air conditioner?
The
capacity of an air conditioner is a term used to measure the cooling
(or heating) time. The capacity required from an air conditioner
differs from region to region (Samsung in SA: Outdoor - 35ºC DB; Indoor
- 27ºC DB / 19,5 WB) and the amount of air it has to cool. Therefore,
one must choose the correct unit by calculating the heat load.
BTU - British Thermal Unit
W - Wattage
DB - Dry Bulb
WB - Wet Bulb
kW - Kilowatt
m² - Area in Metres
ºC - Degrees Centigrade
dB - Noise level in Decibels
How do you
calculate the capacity?
In South Africa, the cooling / heating capacity of an air conditioner is measured as follows:
BTU (British Thermal Unit)
KW (Kilowatt)
1KW = 3412 BTU
What are
heat loads?
Remember, all the air in a given space needs to pass through the refrigeration
cycle (air conditioner) for there to be 'effective control' of that area. Therefore,
air conditioning can only be effective if the area to be cooled or heated is a
sealed environment.
How do you
calculate the heat load?
Here follows a guide only. For a precise heat load calculation, a Heat Load
Calculation Sheet should be completed. For offices, homes and your average
area requiring air conditioning always keep the following factors in mind:
1. Size of the area (m²)
If the height of the ceiling is over 3m, then add on the increased percentage of
the area, or use the Heat Load Calculation Sheet.
2. Exposure to direct sunlight
Is there excessive heat gain from large or many windows or a non-insulated roof etc?
3. Curtains and blinds
E.g. If the area is an office with blinds or glazed windows, the heat gain is reduced.
4. Type of building construction
A brick construction will generally be cooler than a timber or metal one!
5. Number of people in the area and level of activity
An office with two people can be considered a 'standard' heat load. However, an
office of the same size with eight people is not. A person seated at an office desk
gives off less heat than someone who is more active e.g. in a reception area or
a restaurant eating and drinking.
6. Extraction and intake of air
If air is added to an area (e.g. via an open window), this air will be warmer
than the air in the given area and will need to pass through the refrigeration
cycle to lower its temperature, causing the air conditioner to work 'harder'.
Thus the capacity is affected.
7. Electrical equipment in use
An empty office in a building with no people in it might not generate much of a
heat load but, in a computer room, the heat generated by the equipment will
increase the heat load, affecting the capacity. An excessive number of lights will
have a similar effect. Should the area being calculated be considered a 'standard'
heat load, then the following average heat load calculation could be used:
500 BTU / m²
|
