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.

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.

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.

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.

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.

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.

Source: U.S. Energy Information Administration

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.

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.

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.

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.

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

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:

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.

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

Illustration: Brown Bird Design

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.

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.

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.

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.

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.

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:

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.

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.

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.

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.

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.