There are plenty of variables to consider as you shop for your next air conditioning system, including price, brand name, and energy-efficiency ratings. However, size is the most important of all of these variables. All too often, many homeowners make the mistake of buying an air conditioner that's too large or too small for their home, resulting in wasted money and poor cooling performance.
The following explains the importance of making sure your air conditioner is the right size for your home. You'll also learn about the perils of buying an A/C system that's the wrong size for your home.
How Much Cooling Does Your Home Really Need?
Every home has its own unique heating and cooling demands. These demands are typically dependent on your home's overall design, including how well it's insulated from outdoor temperature changes. In order to operate as efficiently as possible, your air conditioner's cooling capacity should be closely matched to the amount of effort needed to keep your home relatively cool.
Most HVAC contractors calculate home cooling demand based on several variables, including your home's square footage and the overall cooling capacity of your A/C system. Some contractors, however, may take the easier way out and calculate home cooling demand based on a general rule of thumb. Despite being faster and less complex than a thorough Manual J load calculation, going by rule of thumb puts you and your contractor at greater risk of choosing an A/C system that's the wrong size for your home.
The Dangers of Oversized and Undersized Systems
There are plenty of consequences to purchasing and installing an air conditioner that's either too large or too small for your home to handle. For starters, here are some of the more common problems that could occur when operating an oversized A/C system:
- Oversized A/C systems are susceptible to short cycling, resulting in increased wear and tear on the compressor and other internal components.
- Oversized A/C systems usually don't run long enough for your unit to dehumidify your home's indoor air, resulting in a clammy and uncomfortable environment.
- Air filtration also becomes an issue because the oversized A/C system doesn't run long enough for your air filter to be effective at removing airborne pollutants.
- An oversized A/C system can also cost you money, thanks largely to higher energy consumption and higher cooling costs.
Undersized A/C systems are often chosen under the mistaken belief that a smaller A/C system is more energy-efficient than one that's larger, but better matched for your home's cooling demands. Here are a few problems that often happen when using an undersized A/C system:
- Undersized A/C systems must run for much longer periods to properly cool your home. As a result, an undersized A/C system can actually waste more energy than a properly sized system.
- Undersized A/C systems can also experience greater levels of wear and tear than their properly-sized counterparts.
- Longer run times can result in air that feels drier, yet warmer due to over-dehumidification and poor cooling performance.
- Insufficient cooling capacity can leave several portions of your home unable to benefit from your A/C system's cooling capabilities.
How to Choose the Perfect Size
Balance is the key to choosing an air conditioner that satisfies your home's cooling needs, yet that also offers superb energy efficiency and low operating costs. Your HVAC contractor usually takes the first step towards choosing the perfect A/C system by performing a Manual J load calculation, followed by HVAC equipment selection under the Manual S procedure. These steps are crucial for purchasing an air conditioner that offers excellent performance that's closely matched to your home's cooling needs.