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What Goes into Sizing an AC Unit?

In the world of air conditioning, bigger isn't necessarily better. You need an air conditioner that's sized to fit your home like a glove to maximize energy efficiency, and going either too big or too small will increase cooling costs and reduce comfort. The best way to breathe easily throughout the summer is with a properly sized unit, and to get there, you need a professional load calculation.

Issues Associated With Improper Sizing

Because of inaccurate sizing methods used by HVAC contractors in the past, many current air conditioners are too large for the homes they cool. An over-sized air conditioner will constantly overshoot the target temperature and shut down, then start up again when climbing temperatures trip the thermostat. The result is a series of uncomfortable temperature changes. More importantly, all that cycling on and off wastes energy, and you'll see the difference on your utility bills.

Things get even worse when an air conditioner is too small for the home it's trying to cool. Undersized air conditioners have to work very hard, which means there's extra wear and tear on the internal components. Over time, that sizing issue can lead to a host of maintenance issues. In the meantime, you'll likely have inadequate cooling, especially on very hot days.

Even if your air conditioner was properly sized when it was installed, it's possible that your home's cooling load has changed over time. That's why, regardless of circumstances, we recommend beginning every air conditioning installation project with a full load calculation.

Professional Load Calculations

Before any AC replacement or installation project, your HVAC contractor will assess your home's cooling needs and put those factors into a load calculation. Some of the key aspects to consider are:

  • Square footage. This is the obvious one. The more space your air conditioner has to cool, the more cooling power it needs. However, most sizing errors come from just using square footage and not accounting for other factors.
  • Layout. The easier it is for air to flow throughout your home, the easier it will be for your air conditioner to cool things down. The height of your ceilings also plays a role because hot air tends to rise.
  • Insulation. All the air conditioning in the world won't do you any good if the cool air just leaks back out of the house. The better insulated your home, the smaller the cooling load.
  • Load-Generating Appliances. Some of the machines in your house may produce a significant amount of heat. That, too, adds to the cooling load.

Based on the results of this calculation, your HVAC contractor will work with you to select the right air conditioner for your home. The upshot is that you'll know that your new air conditioner is sized to match your cooling load, which means it will run at maximum efficiency and provide effective cooling for years to come.

In order to get a professional load calculation and benefit from a properly sized air conditioner, you'll need a great HVAC contractor. That's where we at Comfort24-7 come in. We'll help you connect with a highly qualified contractor who can account for both your home's cooling load and your local conditions. You'll know for certain that your air conditioner perfectly suits your home.

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