Supplemental air conditioners

When sizing your supplemental air conditioner, three factors must be taken into consideration: the size of the area; how long the room is exposed to the sun and the insulation of the walls and windows.
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The three factors to be considered
A few technical clarifications
Operation tips
Air conditioner models
Maintenance

The three factors to be considered

  • The size of the area to be cooled;

  • Rooms located on the south and west sides are harder to cool because of the strength of penetration and duration of the sun on the house

  • Insulation of the walls and windows. If the house is over 25 years old, it may not have sufficient insulation and will consequently require a more powerful air conditioner.

Remember that an air conditioner offers the great advantage of dehumidifying a room while cooling it.

A few technical clarifications

The output of an air conditioner is measured according to the number of BTUs per hour (British Thermal Units produced per hour);

the air conditioning units generally available on the market are 6,000 BTU/H, 8,000 BTU/H and 10,000 BTU/H. A 6,000 BTU/H unit covers approximately 250 square feet; an 8,000 BTU/H, 330 square feet; and a 10,000 BTU/H, 420 square feet, which represents 24 BTU/H per square foot to be covered, taking into account an 8-foot-high ceiling (for a 12-foot-high ceiling, you have to count 36 BTU/H per sq. ft.).
Sizing guide
Maximum
Cooling Area		Room SizeCooling Capacity
(BTU)
150 sq. ft.10 ft. X 15 ft.5,000
275 sq. ft.10 ft. X 35 ft.7,000
325 sq. ft.15 ft. X 20 ft.7,500
350 sq. ft.15 ft. X 20 ft.8,500
500 sq. ft.20 ft. X 26 ft.10,000
650 sq. ft.26 ft. X 25 ft.12,000

Operation tips

  • In order to extend the life of the air conditioner, it is preferable not to use an extension cord when plugging in the unit; however, if you can't do without one, it is highly advisable that you use the shortest extension cord possible, and one having a minimum gauge of 14, with grounding lug.

  • In the case of a bedroom air conditioner, it is preferable to opt for a unit with 8,000 BTU/H, rather than 6,000 BTU/H, and to let it run on low speed, so that you will be able to considerably reduce the noise and the operating time.

  • If you want to cool a number of rooms that are not standard shape, it is preferable that you install a number of air conditioners with 6,000 or 8,000 BTU/H and that you install them at various locations, in order to make sure that the fresh air is being well distributed through the rooms. This solution is more efficient than installing only one single but very powerful air conditioner, such as a 10,000 BTU /H, in a central location in relation to the rooms concerned.

Air conditioner models

For home use, there are three basic models: window-mounted, wall-mounted and portable. Most of the units described below now come with electronic controls and some with a remote. Multi-function units combine one or all of the functions of an air conditioner, dehumidifier, heater, air cleaner and fan.

Window-mounted

Window mounted air conditioners come in two basic modes, horizontal and vertical. The former is designed for sash windows that open vertically and the latter for windows that open from side-to-side. Both units are installed in adjustable frames mounted inside the window casing. When buying a window mounted air conditioner, measure the perimeter of the opened window to make sure that the adjustable frame will fit inside. Install the units slightly slanted outwards to assure water runoff. Units can stay in place all year, but must be “winterized”, drained to prevent ice damage and sealed to prevent cold air leaks.

Wall mounted

Similar in design and function to window mounted units, wall mounted units are set in a chassis in a hole cut through the wall for this purpose. The chassis allows the unit to be removed for winterizing and maintenance. Although more difficult to install than window-located units, once properly installed they free up the windows that would otherwise be used by window models.

Portable

As the name implies portable units, on wheels, can be moved around the home to cool different rooms. This feature allows one to use the unit in the living room during the day and in a bedroom at night. Another advantage is that humidity is vented out a window through a frame that fits in either horizontally or vertically opening windows.

Maintenance

Mainly, maintenance in modern air conditioning units consists of keeping the unit clean and washing the filters. The filters should be cleaned every month that the unit is in operation, can be re-used several times between washings, but need to be replaced periodically. Coils can be cleaned with a commercial air conditioner cleaner. If you need to remove the entire unit from the widow or wall frame, remember to replace worn-out or damaged weather-stripping before resetting it in place.
Would you like to have more information? We encourage you to consult your local home renovation centre.
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