The Problems of an Improperly Sized Air Conditioner

Posted: 2019-07-11

In the past, air conditioning was a luxury enjoyed only by the privileged few. Today, most homes are equipped with AC units, which have become a part of our lives, especially during the summer. Unfortunately, not every home has a properly sized air conditioner installed.

Four Seasons Air Specialists, your trusted HVAC company in Hugo MN, offers you helpful information on the importance of proper AC sizing.


In the world of home comfort systems, size does matter, and bigger doesn’t always mean better. When you decide on which particular air conditioner to purchase this summer, it is imperative that you consult a qualified professional who will determine the best size for your home. He will calculate how much cooling capacity is needed to keep your home comfortable.

A number of factors can affect the AC unit you need, including building materials, the size of your house, which direction it faces, location and number of rooms, the type of windows and doors, their thermal efficiency, your region’s climate, the height of your ceiling, etc.

Here are the reasons why an improperly sized system is such a problem.

Excessive Power

If you have an air conditioner that is too large for your home, it will have excessive power. Since an oversized system cools too quickly, once it reaches its set temperature, the thermostat shuts down the system before it has run its full cycle and properly cooled your home. In HVAC terms, this is called “short cycling”.

An air conditioner is engineered to produce a certain amount of cooled air over a certain period of time, but when it short cycles, it prematurely deteriorates the system. An oversized AC is highly likely to lose some of its efficiency due to short cycling and has a greater chance of breaking down prematurely than a properly sized system.

High Utility and Repair Costs

Oversized air conditioners run much less efficiently compared to properly sized ones. They turn on and off several times throughout the day, using more energy than normal. This results in higher energy bills, not to mention the added cost of repair and wear and tear on the system.

Similarly, an undersized air conditioner can cause a hike on your energy bills. Since the unit has to work harder to cool your home, t uses too much electricity than it should. When summer is at its hottest, it can even shut down your entire system because the motor overheats or the coils have gone ice-cold. Even if you have a programmable thermostat set to your desired temperature, an undersized AC may never be able to provide the level of comfort you want.

Unsatisfactory Comfort

There are two jobs an air conditioner is designed to perform: to cool the air in your home and remove excessive moisture. To remove the moisture, the air should pass over the evaporator coils, dropping the temperature by as much as 20 degrees Fahrenheit. When the temperature of the coil is below the air’s saturation point, water vapor condenses on the coil’s surface.

An oversized system also fails to properly humidify the air that flows over the cooling coils to remove the moisture from the air. This causes your home to be overly humidified, which leads to the growth of mold and mildew. A home with too much humidity combined with high temperatures can lead to a heat stroke, especially if you have preexisting heart conditions.

Unfortunately, with too large systems, the AC cools the room too quickly than normal. As a result, it runs at a much shorter period of time than a properly sized unit. This means that the water cannot condense on the coil and is redistributed into the room. This gives you a sticky feeling, which is definitely uncomfortable.

Hot and Cold Spots

Most homeowners choose smaller air conditioners because of their lower price tag. However, buying a cheaper unit does not necessarily translate into savings. If your air conditioner is too small for your home, it will have a hard time maintaining a consistent temperature. You will notice that some rooms are cooler than the others. In such cases, you may have to buy a secondary cooling system.

Ask the AC Experts

To help you choose the right system for your home, call Four Seasons Air Specialists, your reliable Forest Lake heating and air conditioning contractor.