The Ultimate Air Conditioner Buyers Guide
The Ultimate Air Conditioner Buyers Guide

With the rising climatic and environmental changes, even the cooler regions worldwide face hotter days and scorching summers. When the temperature rises, all we can think of is how to beat the heat and cool off. Air conditioning units are a boon to any household to ensure comfort through these warm days and sweaty seasons. The Census Bureau recorded that over 90% of American families had central air conditioning or window AC units in 2019.

 

For those who do not have the option of central air conditioning, other AC types are an easy and inexpensive way to go. To make sure your summers are stress-free, you need to get your hand on an air conditioning unit that is reliable and meets the needs of your home. Many factors to consider while investing in an AC, including size, placement, portability, etc. This guide will help you determine the exact type and size of ACs that will work the best for you and your family.

How Does an Air Conditioner Work?

The basic operation of an air conditioner is removing heat and humidity from a room or enclosed space and replacing this hot air with cold air. A common mistake is to think that air conditioners create cold air. Instead, they remove heat from your home and transfer it outdoors.

The process, although more technical, takes place with the help of a cooling agent known as the refrigerant and three essential AC components: a compressor, a condenser coil, and an evaporator coil. These components work together to convert the refrigerant from a liquid to gas and back again rapidly.

how does an air conditioner work illustration

Source: U.S. Department of Energy - Energy Saver 101 Infographic

Let’s take a closer look at this process:

Step 1: Typically mounted on a wall in a central location, the thermostat monitors and controls the indoor air temperature. The cooling cycle begins when the thermostat senses the air temperature needs to be lowered and sends signals to the air conditioning system parts inside and outside the home to start operating.

Step 2: A fan from the indoor unit pulls hot air from inside the home through return air ducts. This air passes through filters where dust and other airborne particles are collected.

Step 3: The filtered, warm indoor air passes over the cold evaporator coil. As the liquid refrigerant transforms into gas, heat from the indoor air is absorbed into the refrigerant, cooling the air as it passes over the evaporator coil. The blower fan, located in the inside unit, then pumps the chilled air back through the ductwork into different areas of the home.

Step 4: The refrigerant gas exits through a copper coil and passes into the compressor in the outside unit. The compressor decreases the gas’ volume by squeezing the gas tightly between two solid objects. This complex process raises the pressure and temperature of the refrigerant, preparing it for the condensing process.

Step 5: Now a superheated vapor, the refrigerant reaches the condenser, located outdoors, and is exposed to the outside air. The outdoor air absorbs the heat from the refrigerant, lowering the temperature of the refrigerant and converting it back to a liquid.

What Are the Main Parts of an Air Conditioner?

The working of an air conditioner primarily depends on the refrigerant as it travels through the entire unit to help remove heat from indoor air and blow out cold air. There are five main parts of the air conditioner that support this process:

  • The Compressor
  • The Condenser Coil
  • The Evaporator Coil
  • The Expansion Valve
  • Air Filter

Knowing how these parts work and maintaining them should help you detect problems early before they cause any significant damage to your unit.

air conditioner refrigerant freon 410A

The Refrigerant

Being the substance in the air conditioner that travels through all the mechanical parts of an AC to help regulate the temperature of the air, the refrigerant is one of the most crucial aspects. It runs through the coils and pipes in the air conditioner to do the cooling. The refrigerant has properties that allow it to change at relatively low temperatures, making it perfect for the job to happen quickly.  

scroll compressor for air conditioner

The Compressor

The compressor plays a significant role in the overall cooling system. The compressor takes the heat in the air and forces it outside, allowing the cooled air to circulate inside your home. It does this by turning the refrigerant, in its gas state, through the inner components into a liquid, releasing heat into the outdoors.


If your AC is making a weird sound such as banging, usually this is the first sign that your AC compressor is likely not functioning correctly. The compressor is a complex mechanism inside the air conditioner and should be checked and maintained every few months by a professional. DIY repair and maintenance aren’t advisable in this case.

air conditioner con

The Condenser Coil

Another essential air conditioner element, the condenser coil, removes heat from the unit's interior and helps push it outside. The condenser is made of hollow coils, and refrigerant gas travels to the condenser and enters the coil as part of the cooling process.


The moisture inside your air conditioner could react with the compressor coils and form a corrosive substance, which may eventually damage the condenser and other parts of your system. If your air conditioner is not cooling properly, it may signify that your AC condenser is blocked, dirty, or corroded. These are problems that should only be dealt with by a professional who can use the process of chemical cleaning to get rid of the corrosive acid.

air conditioner evaporator coil

The Evaporator Coil

The evaporator coil, typically made of heat-conducting steel, aluminum, or copper, plays a part in the last step of the cooling process. In liquid form, the refrigerant comes from the condenser coil and into the evaporator to turn back into its gaseous state. As the warm air is pulled into your HVAC unit, it is blown over the cool evaporator coils, extracting the heat and cooling the air down. Fans behind the evaporator coil, then blow this cool air back inside, reducing your home temperature.

While the coil is not directly exposed to the elements, it may collect dust particles or become mildewy over time. When the evaporator coil gets dirty, it begins to run slower and less efficiently, using more electricity. If your AC smells musty, it is one of the first signs that humidity has caused mildew and mold to grow on your coils. 

air conditioner expansion valve

The Expansion Valve

The expansion valve is the part of the aircon that connects the evaporator and the condenser. When the liquid refrigerant exits the condenser, though it dissipates heat and cools down to some extent, it is still not cool enough to enter the evaporator coil. The expansion valve decreases the pressure of the refrigerant further to cool it down even more. The refringent turns into a semi-liquid and semi-gaseous state in the expansion valve. The refrigerant is now cool enough to enter the evaporator and repeat the process. It would be best to get this complex aircon part checked regularly by a professional every few months to ensure the proper function of your air conditioner.

man changing air conditioner air filter in return vent

The Air Filter

Keeping air circulation clean is essential for you and your air conditioner. As much as dust and dirt particles can be harmful to your health, they can also become a hindrance to the optimal working of the air conditioning system.

All air filters work similarly. As your air conditioner is running, air passes through the filter screen. The filter material catches particulate matter such as pollen, dust, pet dander, dirt, and allergens. Some air filters can even remove bacteria and viruses from the air.

Sometimes it becomes difficult to understand why an air conditioner is not working. If your AC is freezing up, the first thing on your checklist should always be to check the filter. Dirty or clogged air filters can restrict airflow, slowing down the cooling process. You can DIY-maintain this by replacing your filter or washing the filters with water and a gentle detergent every month.

Types of Air Conditioners

One of the widely used appliances in homes, offices, institutions, shopping stores, and more, air conditioners are integral to any space. When deciding which AC would best fit your needs, you should consider the budget factor, energy efficiency, cooling capacity, and maintenance requirements. The type of air conditioner you pick can also depend on your geographical location, the size and physical limitations of your home, and how you use it.

 

There are six significant types of air conditioners on the market, and each of them is designed for different spaces with different features. These types of air conditioners are:

central air conditioner - outside/outdoor unit

1. Central Air Conditioner

Perfect for large spaces, central air conditioners can cool multiple rooms simultaneously. Split into two outdoor and indoor units; central air conditioners use ducts to provide cool air throughout a home. The condenser and compressor coil are inside the outdoor unit. While a furnace or a fan coil, including the evaporator coil and blower fan (air handler), remains indoors. Refrigerant helps remove heat from indoor air and distribute cold air evenly in every room.

 

Split-system air conditioners provide various options, including basic single-stage systems, quieter and more efficient two-stage systems, and the quietest, most energy-saving multi-stage systems. A central air conditioner uses an electrical thermostat offering consistent, dependable temperature control throughout the home. The split system uses filters in its indoor air handler, improving your air quality while it cools it.

Advantages of Central Air Conditioners

  • Ducting can be done to cover as many rooms as required
  • The outdoor units are quieter than other AC types
  • Even cooling throughout the space
  • Even air reduces humidity for a more comfortable environment
  • Filters the air, which improves air quality.

Disadvantages of Central Air Conditioners 

  • It consumes a lot of energy, resulting in higher bills
  • Ductwork, soffits and ceilings are required. If your house does not have this infrastructure, the total installation cost will significantly rise.
  • Large outdoor units can be unattractive to the exterior of the home

 

white through the wall air conditioner TTW

2. Through-the-Wall Air Conditioner (TTW)

As the name suggests, through-the-wall air conditioners, or TTWs, are designed for permanent installation into the wall. They are installed on an exterior wall with the support of a wall sleeve and tend to be more efficient than window units because they create an airtight seal. Thru-wall air conditioners are a great alternative to window ACs, perfect for cooling rooms and areas that do not have windows or large enough windows. TTW ACs can include both cooling and heating functions, depending on the model.

Advantages of Through-the-Wall Air Conditioners

  • They are relatively inexpensive
  • Does not block window views
  • They fit into a sleeve, ensuring fewer chances of air escaping
  • Do not require windows for installation in small spaces
  • It can be installed on any exterior wall

Disadvantages of Through-the-Wall Air Conditioners

  • Installation is permanent and they cannot be removed
  • The installation process is more technical
  • They do not have the capacity or ability to cool your whole home
window air conditioner outside of apartment building on fall day

3. Window Air Conditioner

Window air conditioners are among the most common ACs used in households. They target one room at a time but can be used to cool adjoining spaces depending on the size and capacity. These air conditioners are made in various sizes and capacities to offer a versatile range of use to different household requirements. A window air conditioner consists of all the parts and components in a single unit, making it much more efficient and easier to install and maintain.

 

The main concern when choosing a room air conditioner unit is size. If it’s too small, it will have to work overtime to cool the room, and you’ll still have a room that doesn’t feel cool enough. If it’s too big, it will cool the room too quickly without removing the humidity adequately, and you will have a cool space that still feels damp.

Advantages of Window Air Conditioners

  • Easy installation
  • No requirement for permanent infrastructural change for installation
  • Inexpensive upfront costs and cheaper to operate
  • No consumption of floor space
  • Can be remote control operated
  • Easy-to-access filters can be cleaned regularly for efficient working

Disadvantages of Window Air Conditioners

  • Completely block whichever window you choose to install them in
  • Not energy efficient for larger spaces or entire house
  • Can be noisy/get noisier with time
  • A window must be able to support the air conditioner and near an electrical outlet
white portable air conditioner in living room

4. Portable Air Conditioner

Portable air conditioners (PACs) are similar to window air conditioners because they are single, self-contained units ideal for cooling small spaces that cannot accommodate more permanent systems. As the name suggests, portable air conditioners can be easily moved from room to room.

 

There are two main types of free-standing units:

  • Single-hose units work by pulling warm air from inside the room, cooling it through its motor, and expelling the excess warm air and moisture through the hose and then out the window. These units tend to use less energy and cost less than dual-hose units.

  • Dual-hose air conditioners pull fresh air from outside through the one hose, circulates the cool air, and pushes the excess warm air and moisture through the second hose. These units usually cool rooms quicker and more efficiently than their single-hose counterparts. 

Advantages of Portable Air Conditioners

  • Mobility
  • Cost-effective
  • No permanent installation required
  • Easy DIY installation
  • Convenient for apartment rentals
  • Can be packed and stored away when not in use

Disadvantages of Portable Air Conditioners

  • The shorter range of cooling

  • Noisier than other units
  • Consumes floor space
  • Placement restrictions
  • The drain tank needs to be emptied regularly
packaged terminal air conditioner PTAC installed in hotel room

5. Packaged Terminal Air Conditioner (PTAC)

Packaged Terminal air conditioners, or PTACs, contain the evaporator coil, blower fan, compressor, and condensing coil all in one unit. PTACs are ductless systems installed through external walls right above the floor and often below a window. Most models include cooling and heating, and their durable construction makes them popular in commercial spaces such as hotels, motels, condominiums, offices, and shared living spaces.

Advantages of Packaged Terminal Air Conditioner

  • Drastically lower energy costs
  • Permanent and long-term cooling solution
  • Quieter than many window and portable units
  • All-year climate solution

Disadvantages of Packaged Terminal Air Conditioner 

  • Better modern upgrades offer more efficiency
  • Permanent installation
  • Bulky packing
  • Single room installation prevents zone control
white ductless air conditioner hanging on wall in home

6. Ductless Air Conditioner

A ductless (mini-split) air conditioner system is a compact unit designed to heat and cool only a small area of your home. Like central air systems, mini-splits have an outdoor unit containing the condenser and the compressor, connecting to one or multple indoor units with a conduit, which houses the power cable, refrigerant tubing, suction tubing, and a condensate drain. Typically mounted on a wall in a designated room, the indoor unit is equipped with air blowers and is responsible for providing cold air. Each indoor unit acts as a zoning system and can have different temperate settings depending on your comfort needs.

Advantages of Ductless Mini-Splits

  • Easy installation
  • Individual temperature control for different rooms
  • Quiet operation
  • Flexibility for zoning and cooling individual rooms
  • Can be remote control operated

Disadvantages of Ductless Mini-Splits

  • Cost of installation
  • Each indoor unit is wall mounted and can be seen within a room
  • Correct sizing of the system is essential. Over-sized or incorrectly installed equipment often results in short-cycling, wasting energy, and unable to properly control the temperature or humidity.

Factors to Consider Before Buying an Air Conditioner.

While investing in an air conditioner, you invest in daily comfort and stress-free summers. However, not all air conditioners are created equal. Considering the capacity, energy efficiency, air quality, and maintenance requirements is essential. In order to find the perfect cooling system for your home, it is essential to consider these five factors:

1. Capacity

Capacity is the ability of a heating or cooling system to heat or cool a given amount of space. For heating, it is calculated in BTUs (British Thermal Units). Cooling capacity is the measurement of an aircon and its ability to extract heat from a space. It is usually presented in tonnage (tons), which is 12,000 Btu per hour and 3500 Watts of cooling (approximately).

 

The cooling capacity of an aircon relies on many factors, such as the size of the area being cooled, climate, ceiling height, and the number of household members in the space on average. Without calculating the ideal BTUh or tonnage for your space, it’s all too easy to end up with a unit that is too large or too small for your needs, both of which work counterproductively and can waste a lot of money. If your cooling system is too small, it will not have enough power to cool your space. Alternately, if your AC unit is oversized, it will continually cycle on and off—leading to increased electric bills and decreased efficiency. An improperly sized unit will struggle to support sufficient humidity levels, therefore reducing the overall comfort of an area.

2. Energy Efficiency 

Air conditioners with higher efficiency can help save on electricity by using less power. While shopping, search for a unit with an Energy Star certification. Standardized by the U.S. Environmental Protection Agency (EPA), these strict energy efficiency guidelines will keep you informed about whether the cooling system you have picked is efficient or not. Star-rated room air conditioners use 10 percent less energy than traditional models. ENERGY STAR-certified central air conditioners use 8 percent less energy than conventional new models. Remember – the higher the star rating, the higher the efficiency!

 

In addition, be aware of the Energy Efficiency Ratio (EER) measurement. A unit’s energy efficiency ratio is the ratio of cooling energy to the amount of energy (wattage) required to power your unit. The higher the EER, the more efficient the unit. Generally, an EER of 12 or above is considered energy efficient. However, when comparing two different models, the one with the higher EER is more energy-efficient regardless of whether or not it is above 12.

3. Air Quality

The air filter in an air conditioner is responsible for maintaining the air quality circulated through an AC and eventually consumed. According to the United States Environmental Protection Agency (EPA), indoor air can be five times as polluted as outdoor air. Since indoor air is not circulated as much as the outside air, many airborne pollutants flourish inside.

 

It is vital to have an aircon with quality filters to effectively filter out dust, germs, and other contaminants before cooling your home's air. The filtration process improves indoor air quality and helps prevent the coils and mechanisms inside the air conditioner from clogging. Some air conditioners also feature dehumidification units, offering better cooling and comfort.

4. Electrical Installations

It is also essential to check if your electrical system can support the air conditioner you install. The voltage must be reviewed and kept under consideration at all times. The electrical requirements for your cooling system will be listed in the manual specifications. We recommend discussing these details and getting your AC installed by a professional to ensure zero hazards and maximum efficiency, regardless of the type of air conditioner.

5. Maintenance Requirements

Every appliance requires maintenance to remain in the best working condition. Air conditioners should also be cleaned every once in a while. The air filter gathers dust, debris, and dirt over short periods. Depending on the type of filter, it should be washed with regular soap and water every couple of months. Every AC should be serviced at least once a year, while central air conditioning systems should be checked by professionals regularly.

What is a SEER rating?

A SEER rating, or the Seasonal Energy Efficiency Ratio, is an easy way to compare air conditioner efficiencies. Typically, a higher SEER rating means greater energy efficiency. In 2023, new regulations will require the north region of the United States to increase from 13 to 14 SEER and the South/Southwest to increase from 14 to 15 SEER.

heat pump energy guide label example

The energy guide system was created due to legislation passed in 1987 that required air conditioners to have minimum performance levels.

SEER is a mathematically defined ratio of the cooling output provided during the entire cooling season (not to exceed 12 months) divided by the total electric energy input during the same time frame.

Required by the United States Department of Energy (DOE), all air conditioners must meet a minimum SEER efficiency rating. A SEER rating helps you compare multiple options and determine which one is the best for your household to save power and costs efficiently. The SEER rating for your aircon unit will be listed on a sticker usually found on the exterior of the unit.

What SEER rating should I buy?

A higher SEER rating offers better energy-saving efficiency, making it an ideal option. However, there are many factors to consider in determining what SEER rating is suitable for your house. These can include the location, climate, and size of your home and what you're looking for in a heating and cooling system.

The SEER rating is established on the region, as the measure considers the environment, weather, and other conditions that affect households' average heating/cooling needs in specific areas.

In 2023, new HVAC efficiency standards set by the United States Department of Energy (DOE) will require a minimum SEER of 14 for the northern U.S. states and 15 for the southern U.S.

Year Northern Regions South and South West Regions

1992

10

10

2006

13

13

2015

13

14

2023

14

15

SEER ratings use standard formulas to help you determine how much you can expect to pay annually in energy costs. A buyer can quickly compare the different operating expenses of air conditioner models with SEER ratings. Generally, the more energy-efficient system has a higher rating.

Remember, though, a SEER rating is an average. While considering a SEER rating, it is also important to remember that this rating does not refer to the level at which your air conditioner will constantly function. This rating measures the maximum efficiency your AC can offer but does not mean it will always do so. Other factors such as the number of windows, size of the home, ductwork, etc., can weigh in on how efficient your cooling system is.

To understand this, air conditioner SEER ratings can be compared to a car's gas mileage. For instance, if your vehicle can run up to 30 miles per gallon on an empty road or highway, it does not necessarily mean it should, or will, run at the same rate every time. Traffic, road quality, weather, and other factors can change this and lower your car's miles per gallon. In the same way, your air conditioner will not always work at the same level of efficiency with so many different variables.

Is a higher SEER rating worth it?

Even though it might seem like the highest SEER number possible is the best unit for your home, this isn't always true. While a high SEER rating indicates the air conditioner's advanced ability to remove heat from your home throughout a cooling system efficiently, an 18-plus unit isn't always the best choice.

Typically, a higher-rated SEER air conditioner is more expensive. While you can find high SEER number cooling systems at various price points, the quality and technology used in most air conditioners come at a more significant initial purchase cost than a lower-rated unit.

If you want to lower overall aircon-related costs, you need to calculate the cost savings of a higher SEER unit versus the initial purchase price. Some high-prices/high-SEER units may not pay for themselves over time.

Beginning January 1, 2023, the Department of Energy's new HVAC regulations and minimum efficiency standards will change the SEER ratings. Learn how the 2023 HVAC Efficiency Standards can affect your next air conditioner, heat pump, or packaged system purchase.

2023 seasonal energy efficiency ratio SEER standards for the United States map

Source: U.S. Energy Information Administration

SEER Ratings Chart

Upgrading from a less efficient air conditioning unit to a more efficient one (assuming everything else is the same) will save you money. For example, if your current air conditioner is more than ten years old, it could be as low as a 13 SEER. Compare the annual cooling bill of a 13 SEER system to that of a new unit with a higher SEER. If the annual energy bill of a 13 SEER 3-ton system was $482, it could cost only $348 for an 18 SEER system or an annual savings of 28%.

The following chart shows the anticipated savings due to improved SEER efficiency based on the 1320 cooling hours and 13.19 cents/kWh average for the United States.

*Minimum efficiency established by the Department of Energy. The majority of systems installed after 2006 are 13 SEER or higher. Actual energy savings may vary depending on thermostat or control system settings, usage, maintenance, local climate, installation of equipment, and duct system in place.

Higher SEER often means better comfort.

Higher efficiency air conditioners usually come with a 2-stage cooling and a variable-speed fan. These features improve the unit's energy efficiency and provide better cooling than a lower-rated AC can provide.

A standard single-stage air conditioner has two modes: on and off. A two-stage aircon operates at total capacity on hot summer days or 60% to 70% capacity for milder days.

Say you set your thermostat to 73 degrees. Your air conditioner might let the home get to 74 before kicking on, then cool it to 73 or 72. Then the process repeats.

With a two-stage compressor, your cooling system can work less when the temperature is close, therefore using less energy and controlling the need to turn on and off to 100%.

It may seem that two-stage air conditioners run longer than traditional single-stage units. Still, this part-capacity operation offers energy-saving benefits that you will feel throughout your home:

  • Even cooling. The longer run times help the air in your home circulate better, reducing hot/cold spots and providing more precise temperature control throughout your home.
  • Less humidity. Running longer allows the air conditioner to remove twice as much moisture and humidity from your home. Leaving you feeling less sticky and more comfortable.

But won't longer run times mean higher energy costs?

That's a great question, but the answer is no. As with our previous car analogy, an air conditioner costs less to operate when it stops and starts less often. Each time an air conditioner starts up, it costs more because of the energy needed to start it back up.

What does BTU stand for?

BTU stands for British Thermal Unit. It is a unit of measurement for the energy your air conditioner uses to remove heat from a room in one hour. For that reason, the more BTUs an air conditioner unit has, the better equipped it is to cool a larger space.

What is a ton (tonnage)?

Tonnage is not a measurement of your AC’s weight. A ton, also known as tonnage, refers to the total amount of heat an air conditioner can absorb to reduce a room's temperature within one hour. One ton of cooling (also called refrigeration) refers to the heat needed to melt a pound of ice over 24 hours.

 

British Thermal Units and tons are often used interchangeably to determine the aircon's cooling capacity. Tonnage is more commonly used while buying air conditioners as it is in smaller numbers and easier to calculate and understand. Here is how -

 

If we compare tonnage and BTUs, we will find that 12,000 BTUs is equivalent to 1 ton. Tonnage ratings commonly increase by 0.5 tons. For example – 2, 2.5, 3, 3.5, etc. Tonnage requirements vary from home to home and room to room, but typically, most spaces need 1 ton for every 400-1000 square meters of the area to be cooled.

What air conditioner size do I need?

Regardless of which type of cooling system works best for your space, calculating the proper size will provide the best comfort, performance, and energy efficiency.

AC units are generally rated in cooling capacity and energy efficiency. When you ask, "what size AC unit do I need?" you'll be interested in the unit's cooling capacity, which is calculated in BTUh or tonnage. To compare energy efficiency between different air conditioners, you'll want to reference the SEER, or Seasonal Energy Efficiency Ratio, which is like the air conditioner version of miles per gallon for a car.

mother and young daughter enjoying through the wall air conditioner in living room

BTU Calculation

To choose what cooling system is right for you, you need first to calculate the size of the space served by the air conditioner in square feet.

Square Footage = Length x Width

As a general rule, all the BTU calculations, EPA, and Energy Star recommendations presume you have an 8-foot ceiling height. So we can measure square footage rather than the volume of air (length x width x height).

Once the total square footage is calculated, you can estimate how many BTU you need. According to the DOE, for every one sq ft of living space, you should have 20 BTU of cooling output.

For example, you're looking to cool down a 1,00 sq ft area. Let's use the EPA's rule of thumb:

BTU Requirement = 1000 sq ft x 20 BTU per sq ft = 20,000 BTU

AC Tonnage per Square Foot

Before buying an air conditioner unit, you must calculate the AC tonnage. Not sizing an air conditioner unit properly can cause thousands in wasted air conditioner costs or future electricity costs.

It would help if you converted BTU to tonnage. One ton equals 12,000 BTU. That means that, on average, you will need 0.0016 tons per square foot.

For example, an average 2,100 sq ft house would need a 3.5-ton air conditioner. To help, here is a quick reference table showing how many tons (and BTUh) you need for specific square footage:

Area Square Footage BTUs Air Conditioner Tonnage

600 sq. ft

12,000 BTU

1 Ton

900 sq. ft

18,000 BTU

1.5 Tons

1,200 sq. ft

24,000 BTU

2 Tons

1,500 sq. ft

30,000 BTU

2.5 Tons

1,800 sq. ft

36,000 BTU

3 Tons

2,100 sq. ft

42,000 BTU

3.5 Tons

2,400 sq. ft

48,000 BTU

4 Tons

2,700 sq. ft

54,000 BTU

4.5 Tons

3,000 sq. ft

60,000 BTU

5 Tons

3,300 sq. ft

66,000 BTU

5.5 Tons

3,600 sq. ft

72,000 BTU

6 Tons

Proper sizing is crucial for efficient air conditioning. Buying a larger capacity room AC unit than is needed won't make your space feel more comfortable during the hot summer. If an aircon is too big for the area, it will function less efficiently and less effectively than a smaller, appropriately sized unit. An oversized system will cool the room(s) to the thermostat set-point before properly dehumidifying, making the area feel "sticky" and uncomfortable. A small AC unit operating for an extended period works more efficiently and is more effective at dehumidifying than a larger system that cycles on and off too often.

Additional Variables

Along with the size of your area, many variables must be considered when determining the correct size air conditioner for a home. Additional factors to take into consideration include:

  • The average number of people at home at a time
  • Sun exposure
  • Types and numbers of heat-generating appliances or equipment
  • Weather conditions and climate region
  • The total number and size of exterior windows
  • Types of construction, such as brick exterior or vinyl siding
  • The interior ductwork/airflow
additional information to consider when purchasing an air conditioner room illustration

Illustration: Brown Bird Design

Room Properties BTU Adjustment

Heavily shaded room:

-10% BTU calculated capacity

Very sunny room:

+10% BTU calculated capacity

If the room is a kitchen or a room with high tempature appliances:

+4,000 BTUs

Room regularly occupied by more than 2 people:

+600 BTUs per every additional person

How long do air conditioners last?

An air conditioner lasts for 15-20 years on average, but only with the appropriate maintenance and upkeep. Like any appliance, the lifespan of your HVAC system depends on numerous factors such as the size of your AC, maintenance schedule, thermostat setting and placement, installation, and usage patterns.

On top of their maintenance game, even the best cooling systems will eventually run their course over time. You need to know how long air conditioners last, what factors affect their life expectancy, and how to identify the signs that it’s time to replace the entire system.

The lifespan of an air conditioner varies based on different factors. Here is the list of the five common factors that impact life expectancy:

old central air conditioner unit - outdoor

Size of AC

Frequently overlooked, the size of your air conditioner unit can significantly impact the life span of your HVAC unit.

  • Too small - it will need to run for longer durations to cool your house. Undersized cooling capacity can cause overheating and become a risk to the air conditioner's internal working parts, impacting the unit's life span.
  • Too large - it will cool your home quicker. Large cooling capacity will result in shorter cooling cycles, meaning the air conditioner will turn on and off more frequently – also a factor that can harm the unit.

Air Conditioner Maintenance

As you would expect, routine maintenance is recommended to help extend your cooling system's energy efficiency and lifespan. Most homeowners can inspect, clean, or replace an air filter, but an HVAC professional will dig deeper with regular tune-ups. They can clean and inspect components like the compressor, evaporator coil, condenser coil, fan, and condensate drains. Frequent check-ups and minor repairs can improve performance and potentially help prevent more significant problems and a higher repair cost.

Thermostat Setting and Placement

As insignificant as it may seem, thermostat settings and placement play an essential role in your air conditioner's life and durability.

Constantly changing the temperature settings or not changing them enough can cause your unit harm. The thermostat settings must follow the seasons and time of day. Noon will be sunnier, and nighttime will be more relaxed, making it essential for you to change thermostat settings. Determining the right temperature will help save power, reducing stress on your air conditioning system.

As an example, if a person keeps their thermostat set at 70⁰ F during the summer, that unit will likely run more frequently than the house across the street that keeps its thermostat set at 75⁰ F. Over a timeline of 15 years, and with similar maintenance schedules, that difference in usage can have a significant impact on the lifespan.

The physical placement of the thermostat can also affect the life and efficiency of an air conditioner. If installed in a hot or sunny spot, the temperature reading it takes can be incorrect. Your unit will have to work for extended periods to lower these false, fluctuating temperatures, resulting in more increased energy utilization and a reduction in its average lifespan.

Air Conditioner Installation

It is best to have your cooling system installed by an HVAC professional, as it reduces the chances of malfunctioning. However, if your system is ductless and you do decide to do it yourself, make sure you take care of the following so that they do not impact the life span of your air conditioner in the long run:

  • Insulation – if your room isn't adequately insulated, cooling will take longer, meaning your AC will have to work harder to reach the desired temperature.
  • Wiring – incorrect and faulty wiring can be a significant risk and cause damage within the system.
  • Piping – connecting the indoor and outdoor unit with unnecessarily long refrigerant pipes affects the unit's cooling cycle. The more extended travel for the refrigerant drastically overworks the compressor.
  • Ducting – If your system is ducted, correct sealing is highly vital. There should be no leakages, cracks, or gaps in the venting system.

Air Conditioner Usage Patterns

Keeping your AC unit on all day and night, there will be more wear and tear due to non-stop running. Overworking your air conditioning unit can reduce its average life cycle. It's best to use your air conditioner only when you need it. Using smart thermostats can run your unit optimally all day, allowing it to switch off when your ideal room temperature is achieved automatically.

If you like your air conditioner to keep on working 24 hours, seven days a week, and also want to extend its life, you should:

  • Close the blinds, and use ceiling fans and dehumidifiers to minimize the air conditioner's working load.
  • Use smart thermostats or AC controllers to help maintain the temperature and humidity levels without overstressing the system.

When should I replace my air conditioner?

There are many factors to consider when deciding whether to repair or replace an air conditioner system. These include:

  • The age of your unit
  • Its performance and efficiency
  • The cost and frequency of repairs

Like an old car, air conditioners start showing signs of failure before they stop altogether. By being aware of the performance of your older A/C unit, you can begin researching and preparing for the purchase of a new system before you need it.

Here are the top five signs it's time to replace your air conditioner:

excessive humidity and moisture build-up on window from old air conditioner unit

Excessive Humidity

Every air conditioner will produce moisture to some capacity, but those functioning correctly should be able to handle it without issue. When moisture build-up is present or leakage occurs around the unit, it could signify that you have a refrigerant leak on your hands. Leakage will cause the system to underperform, posing a severe health risk to you and your family. Even if it’s just water building up, allowing the problem to persist can create a breeding ground for mold.

weird sounds coming from old air conditioner

Weird Noises

Different air conditioner unit noises may indicate other things, but loud and disruptive sounds signify that your system has reached the end of its life.

  • Banging noises: If your AC is making a banging noise, this indicates a problem with the compressor. This component allocates refrigerant to various parts of the HVAC system to remove excess heat from your home. As your unit reaches the end of its lifespan, it is not uncommon for parts to become loose inside the compressor.
  • Screeching sounds: If your air conditioner is making a shrieking noise, this is an indicator of an issue with the fan motor or a broken motor in the compressor of the condenser system.
  • Humming noises: You may notice a humming noise inside your air conditioner due to a defective contactor relay switch. This component starts the outdoor condenser unit when it receives a cue from your thermostat. You should not turn on your AC until an HVAC professional checks this issue.
  • Buzzing sounds: This sound may indicate loose or unbalanced fan blades in your outdoor condenser unit. It could be from a refrigerant leak, faulty outdoor fan motor, dirty condenser coils, and loose parts.
HVAC technician  repairing central air conditioner outdoor unit

Too Many Repairs

Continuous breakdowns also mean frequent repairs, and the cost of those repairs can add up. It might be more economical to purchase a new cooling system at a certain point rather than spend money on expensive repairs—especially if your warranty has expired. A general rule to follow is that if the repair costs 50% of the original price of your air conditioner, it is better to replace it.

central air conditioner compressor breakdown

Compressor Breakdown

The compressor is the heart of an A/C unit. It pushes the refrigerant through the system and transfers heat from the inside to the outside. When a compressor fails, the air conditioner fails. The fans may still run, but cool air will not come out of the vents. When an AC compressor breaks down, it is one of the most expensive components to replace.

If the air conditioning system is still under warranty (usually, this means it’s less than ten years old), then replace the compressor.

In most situations where a compressor dies, the air conditioner is old and beyond its original warranty coverage. Broken compressors often happen when a unit is 15 years old. At this point, you should weigh your options as purchasing a new compressor is expensive and most likely not worth it.

man with shocked face looking at energy bill from old air conditioner

Energy Costs Have Increased

Unless there are sudden changes in your home's energy use, your energy bill should stay around the same every month, fluctuating slightly for the winter and summer seasons. If your energy use patterns have stayed the same, but your monthly bill has noticeably increased, it might indicate that you need a new air conditioner system.

Higher energy bills can indicate that your air conditioner is malfunctioning or losing efficiency. Energy bills often increase as an air conditioner gets older, so the two issues can be related.

A high energy bill occasionally isn't a cause for alarm. However, if your energy bills spike and don't come down, you might need to start researching your air conditioning options.

Have any questions?

The Furnace Outlet offers the lowest prices on residential HVAC supplies online. Please get in touch with our experienced technicians with any questions or concerns you may have, and we will be happy to help.

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