A Guide to Air Conditioners and Fans

by DoItYourself Staff

Window-Mounted Air Conditioner

Cools, circulates, filters and dehumidifies the air.

Ranges in size from small units with a cooling capacity of 5,000 BTUs (enough to cool a small room) to capacities as high as 12,500 BTUs.

It is important that customers carefully choose the right size of air conditioner. An oversize unit will cool but leave a damp and clammy feeling because of high relative humidity. An undersize unit will not operate effectively on very hot days.

Select by BTU rating, not horsepower. BTU is the actual cooling capacity of the unit.

Determine the efficiency of the unit by dividing the watt rating into the BTU output. The unit must have an energy efficiency rating (EER) of at least 9.7 for models under 8,000 BTU/hr and 9.8 for larger models. The most efficient models have an EER of 11 and higher. Each model should have its EER clearly marked.

Most models should include window-mounting kits. Kits include sill brackets for extra support of the unit and side vents to ensure an airtight fit in the window.

Make sure the unit is designed for the type of window the customer has. Most are designed for double-hung windows, but some are made or casement windows or for in-wall installation.

Portable Air Conditioner

Used to cool a small space, usually 400 to 450 square feet.

Mounted on wheels for easy movement from room to room.

Contains both the hot and cold side of the air conditioner in one unit. Is not permanently installed, but must be connected to some place like a window where the hot air can be vented. Most models contain window-venting kits that are easy to install and easily moved from one window to another.

May be either single or dual vent. Dual vent models circulate clean air back into the room and generally cool more quickly than single vent models.

Drip models have a tray that will need to be emptied every 24-48 hours. No-drip models may cost more but do not produce any excess moisture.

Window Fan

Uses less energy than air conditioning and contains no chlorofluorocarbons.

Brings fresh air into the room while expelling hot air.

Typical size is 20”.

Larger window fans require mounting kits and side panels. The panels support the fan and prevent air from circulating around and back into the fan, resulting in a loss of performance.

Smaller units are easiest to install, as they come with the panels attached to the fan.

Used to intake and exhaust, for bringing inside air into a room or expelling inside air out of a room. Better models have electrical reversibility, which allows the user to switch from exhaust to intake without turning the fan around.

Floor Fan

Can be moved anywhere in the home to provide air movement that will cool and circulate air.

Sizes are generally 10” to 12” in diameter. They can be mounted in rectangular or round, hassock-type case.

A hassock fan throws air outward and upward in a 360° direction.

A rectangular fan will tile about 170° and may be used as a table fan, throwing air outward.

Typically has a speed-selection control, while some may run at a fixed speed.

One variation is the stand-mounted fan. This type can generally be easily tilted and may be used as an exhaust fan if placed near a window.

Oscillating Fan

Moves back and forth in an adjustable pattern to spread air over a larger area.

Oscillation function can generally be switched off with the turn of a knob.

May be used on the floor, a table or mounted on the wall.

Usually does not have as high an air delivery as floor fans.

Typically ranges in size from 8” to 16” in diameter.

Tile angle varies from about 50° to 90°.

Exhaust Fan

Used primarily to extract stale air from an attic, kitchen or bathroom.

Kitchen fans are installed above the kitchen range or under the range hood and prevent smoke and grease from accumulating in the kitchen and spreading throughout the house. A switch simultaneously starts the fan and opens an outside vent.

Bathroom fans may come with an optional light or heater and are used to expel steam and odors from the rooms.

Should carry certified sound ratings developed by the Home Ventilating Institute and its member manufacturers. Ratings are in steps of 0.5 sones and 10 (CFM) cubic feet per minute. Limits for sound outputs are 6.5 sones for bathroom fans and 9 sones for kitchen fans up to 500 cfm.

Whole-house Fan

Draws hot air from the living area into the attic where it is vented outside.

Installation and operation costs less than an air conditioner.

Keeps a gentle breeze stirring throughout the house and can make the temperature seem 2° to 3° cooler.

Has louvers that open automatically when the fan is turned on and close when it is turned off to seal out outside air.

Rated according to the measurement of cubic feet of air per minute (CFM) that it moves.

Fans with variable-speed motors cool the house at higher speeds and maintain general air circulation when turned down.

Ceiling Fan

Creates a gentle indoor breeze and supports heating and air conditioning systems by using less energy than a 100-watt light bulb requires.

Typical sizes are 36”, 42”, 48” and 52”, and some industrial models are as large as 56” to 72”.

Many models combine the fan with a light fixture.

Most ceiling fans have variable speed controls.

Standard mounting kits are available for ceilings as low as 8’ and close to-the-ceiling models can be used on 7’-6” high ceilings.

Blades may be real wood, metal or plastic.

Heavy-material motor housings will aid fan efficiency as the additional mass gains more momentum, reducing the energy necessary to keep the fan in motion.