Especially for those with limited space in which to store their HVAC units, a packaged unit can be fairly beneficial due to its spatially efficient design. Package units are located either on the roof or on the side of a building, and they house a number of combined HVAC systems, like the packaged air conditioners that include a compressor, coils and air handler, the packaged heat pumps that contain a heat pump and often an electric heat strip, a packaged gas-electric unit that combines an air conditioner with a gas-powered furnace, and a packaged dual-fuel unit that contains a heat pump and a gas furnace. There are no indoor components of this central air system.
In order to pick out the best cooling only (air conditioner) package unit, you’ll first need to calculate the square footage of the space that you’re trying to cool. Typically, the average home requires one ton of air conditioning per 400 to 1,000 square feet. There is a lot of variation in this number since you’ll also need to factor in how many windows the space has and how tall the ceilings are, as these things dictate how easily air flows through your space.
After you have discovered what tonnage will work best for your space, you will then move on to figure out what SEER, or Seasonal Energy Efficiency Ratio, you want your new unit to possess. Essentially, the SEER rating measures the air conditioner's efficiency, which is calculated using the cooling output for a typical cooling season divided by the total electric energy input during the same time frame. Similar to the miles per gallon for a car, an air conditioner's SEER rating is the maximum efficiency rating for the unit. So, the higher the SEER rating, the more efficient the air conditioner will be, likely resulting in lower utility bills and other added benefits. However, it is also important to note that the efficiency of your air conditioning system can also depend on the size of the space you're attempting to cool, your current ductwork, and other variables.
Disclaimer: Before making a purchase, you should always check first with your qualified installer to figure out what unit is best for your home or space.