Friday, June 19, 2015

Matching the Right Room Air Conditioner



Room Air Conditioner’s Energy Efficiency

The efficiency of a room air conditioner's is calculated by the energy efficiency ratio (EER). The EER is the ratio of the cooling capacity, in British thermal units (Btu) per hour) to the power input (in watts); the higher the EER rating, the more efficient the air conditioner. Each increase of 1.0 on the EER scale represents a 10% increase in energy efficiency.

The information about the EER of a new room air conditioner can be found on the EnergyGuide label for the unit. Look for an EER of at least 11 and the ENERGY STAR level (an international standard for energy efficient consumer products originated in the United States, created in 1992 by the Environmental Protection Agency and the Department of Energy). Earning the ENERGY STAR meets strict energy efficiency guidelines set by the U.S. Environmental Protection Agency and the U.S. Department of Energy.

ENERGY STAR qualified room air conditioners use at least 15% less energy than the old models. It often includes timers for better temperature control which uses the minimum amount of energy that is needed to cool the room.

Measuring the Required Room Air Conditioner

The required cooling capacity for a room air conditioner is dependent on the dimension of the room to be cooled. Room air conditioners have cooling capacities that range from 5,500 Btu per hour to 14,000 Btu per hour.

An over-sized air conditioner is less effective and wastes energy at the same time. Air conditioner eliminates both heat and humidity from the air. The unit that is too large cools the room quickly, but only removes some of the humidity. This leaves the room with a moist, clammy feeling. A properly sized unit removes humidity efficiency as it cools.

Other Factors to Consider when Acquiring Airconditioner:

Make sure that home's electrical system can meet the unit's power requirements. If mounting an air conditioner near the corner of a room, find a unit that can direct its airflow in the desired direction for room layout. If there’s a need to mount the air conditioner at the narrow end of a long room, look for models that have a “turbo” fan mode that can drive air further into the room. Other features to look for include: 
  • A filter that slides out easily for regular cleaning
  • Logically arranged controls
  • A digital readout for the thermostat setting, and
  • A built-in timer. 

Mounting and Operating Room Air Conditioner

A little planning before installation could help you to save money and energy. The unit should be level when mounted, so that the inside drainage system and other mechanisms work efficiently. Install the unit in a shaded spot on your home's north or east side if possible. Direct sunshine on the unit's outdoor heat exchanger lessens efficiency by as much as 10%. Plant trees and shrubs to screen the air conditioner, but do not block the airflow.

Don't place lamps or televisions near the air-conditioner's thermostat; this senses heat from these appliances, which can cause the unit to run longer than necessary.

On summer, set the unit’s thermostat as high as is comfortably possible. The less difference between the indoor and outdoor temperatures, the lower the overall cooling bill will be. Don't set the thermostat at a colder setting than normal when turning on the air conditioner as this will not cool the house any faster and could result in excessive cooling and unnecessary expense.

Set the fan speed on high, except on very humid days for more comfort. The low speed on humid days cools home better and removes more moisture from the air because of slower air movement through the cooling equipment.

Consider using an interior fan in combination with window air conditioner to spread the cooled air more effectively without greatly increasing electricity use. 

Steps to identify the correct size of Airconditioner for a room
  
Identify the square footage of the area to be cooled.
Cooling capacity is computedin British thermal units (BTUs) per hour.

Consider adjustments for the following conditions:

Reduce the capacity by 10 percent if the room is heavily shaded.

Increase the capacity by 10 percent if the room is very sunny.

Add 600 BTUs for each additional person if more than two people regularly occupy the room.

Increase capacity by 4,000 BTUs if the unit is used in a kitchen.

For the purpose of chart below, rooms that are connected by permanently open entrance ways wider than five feet has to be considered as single room which square footage should be combined.

Area to be Cooled         Capacity Needed
    (Square Feet)             (BTUs per Hour)
       100 to 150                       5,000
       150 to 250                       6,000
       250 to 300                       7,000
       300 to 350                       8,000
       350 to 400                       9,000
       400 to 450                     10,000
       450 to 550                     12,000
       550 to 700                     14,000
       700 to 1000                   18,000
     1000 to 1200                   21,000


References:
  1. https://www.energystar.gov/products/how-product-earns-energy-star-label, How a Product Earns the ENERGY STAR Label 
  2. Josh Kirschner on June 09, 2014How to Select the Right Room Air Conditionerhttp://www.techlicious.com/how-to/select-the-right-room-air-conditioner/

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