Most people think that the size of the air conditioner refers to its physical dimensions. However, this is not true. The AC size is its cooling capacity that is measured in British Thermal Units or BTUs. Irrespective of which AC one selects, an optimum sized AC that is based on the room size will:
- Ensure its best efficiency performance and
- Lower its operational costs.
Thus, even before looking into the nitty-grities of AC buying, it is important to calculate the space it will have to cool.
Cooling area calculation
This is very simple and can be obtained by multiplying the length and breadth of the cooling area. This area when multiplied again by 25BTUs gives the cooling capacity required from the AC to be purchased.
While the above formula works for a rectangular space, for triangular spaces, the formula for calculating the room size is (length x breadth)/2. For an odd-shaped room, the room needs to be broken down into squares, rectangles, triangles and then measurements taken accordingly to calculate the area.
Purchasing a smaller AC will affect the air conditioner service. Such inverters will only run thereby increasing the energy bills without much cooling the room.
Large-sized ACs will have a higher cooling capacity. Thus, they will cool the room very quickly thereby:
- Making people catch a cold from the extreme difference in temperature and
- Extracting all moisture from the room.
Such large-sized ACs will switch on and switch off with alarming frequency that might harm the compressor of the new machine. Additionally, the user would also have to buy a humidifier thereby adding to the AC costs.
Thus understanding the cooling area and opting for an optimum sized AC based on it will ensure the correct buy.
It is also very important to note here that a higher BTU indicates that the AC will cool the room faster and is hence the better AC. However, in reality, there are very few ACs that match up to the mentioned AC BTU. Thus, the BTU should not be the sole criterion on which to purchase the air conditioner.
Factors affecting BTU calculation
However, certain other factors also affect the BTU or AC cooling capacity. They are:
- Ceiling height: For rooms with ceiling height more than the standard 8ft, ACs with higher BTU should be chosen to factor in the room height. Rooms that have a ceiling height of fewer than 8ft should opt for an AC with lower BTU.
- Sunlight: The amount of sunlight entering the room has a strong impact on the cooling capacity of the AC. For sunny rooms, the BTU required should be increased by 10% for optimal air conditioner service. For rooms that are shaded, the BTU should be decreased by 10%
- Occupants: More the number of occupants using the room, the higher should be the cooling capacity of the AC.
- Kitchen: When installing AC in the kitchen, the BTU calculated should be increased by 4000 units.
Buying an undersized or oversized AC is one of the most common mistakes people make when buying an AC. Thus, the size of the room should be taken into consideration and the purchase based on it.