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3 Dangers of Oversizing Your AC Unit


As a homeowner, you probably understand why your HVAC system is so important. From heating and cooling to ventilating the air and protecting its overall quality, this system is an essential part of your family's comfort and well-being. Unfortunately, some homeowners are under the impression that the bigger the AC system is, the better it will be — but this is not actually true.

This guide and your contractor's help will teach you a few dangers of oversizing your AC unit.

1. Decreased Comfort

During the warmer seasons, you want your air conditioner to cool the home so that you and your family can be comfortable. An oversized unit cools your home faster but will not cool for long enough to pull the moisture out of the air. This leads to high levels of humidity.

To understand how humidity decreases your comfort, you must first understand the air-conditioning process.

To remove both heat and humidity from the air, air must pass over an evaporator coil in your system. As it passes over the evaporator, the air drops to a much lower temperature. Water vapor then condenses on the evaporator coil.

With oversized systems, the air conditioner will not run long enough for the water vapor to condense on the coil, so water vapor moves back into the home. Your room may be cooler, but the air will have a muggy, sticky feeling that makes you less comfortable.

2. Poor Air Quality

The higher levels of humidity caused by an oversized system can also affect the air quality of your home. If humidity levels reach 70 to 80 percent or higher in your home, the air quality will affect your health and wellness.

Humidity makes the air stagnant, allowing moisture to trap pollutants and allergens, such as dust, pollen, smoke, and mold. These allergens can affect your ability to breathe properly, increasing the risk of respiratory illnesses, such as asthma.

Humidity levels that measure at 60 percent or higher can also lead to mold growth in the home. Mold is unattractive, and it is also dangerous. Excess exposure to mold can irritate your skin and eyes while causing serious breathing problems.

If you are experiencing one or more of the following symptoms, you may have allergies related to high humidity in the home:

  • Itchy, watery eyes

  • Sneezing

  • Coughing

  • Runny nose

  • Shortness of breath

  • Wheezing

  • Tightness in chest

  • Skin rashes

The above symptoms do not necessarily mean that you have high levels of humidity in the home, but they are indicators that you have allergies or a respiratory illness.

3. Home Damage

Your home, furniture, and belongings will also be affected by high levels of humidity. Because wood and drywall are both porous, moisture can easily seep in, affecting the look and structural integrity of your home's walls, trim, floors, and furniture.

For example, wood floors will start to warp and buckle. The moisture will also prevent cabinet drawers and doors from closing properly.

You may also notice paint and wallpaper beginning to peel, and crown molding, switch plates, and outlet covers may start to bend and come off the walls.

Finally, pests, such as cockroaches, spiders, and rodents, are attracted to moisture. If you have high levels of humidity in your home, a pest infestation is likely to occur, which can cause even more damage to the interior and exterior of your house.

If your system is oversized, your comfort, your health, and your home will be affected. Contact us at Krauss & Crane, Inc., for a load calculation, which can determine if your AC system is oversized for your home.