How Do Evaporator Coils Work?

How Do Evaporator Coils Work?
Evaporator coils inside AC units provide the refreshing air that blows into your living space and brings you relief throughout the summer. This critical component of a central air system is part of the indoor unit, usually near the air handler, and it consists of copper tubes that can efficiently conduct heat. Working side by side with the condenser, which releases the collected heat outside, the evaporator absorbs the heat from inside your home. Clean, efficient evaporator coils offer the following benefits for your living space:
  • Reliable heat absorption and cooling capacity
  • Lower energy use and more affordable utility bills
  • Reduced pressures and temperatures
  • Prevention of frost and ice buildup

What Do Evaporator Coils Do?

Evaporator coils control the refrigerant flow throughout your heating and air conditioning system to remove the heat from a room and transport it outside. Refrigerant is a cold fluid inside the air conditioner that controls heat exchange during the refrigeration cycle. The evaporator coils, hidden behind small, metal fins, receive the refrigerant from the expansion chamber to begin cooling your home. An AC unit has several components that allow it to work, with each part working together to achieve the cold air you desire for your home in the summer. Air conditioners don't blow cold air into a living space like a gas furnace blows hot air. Instead, AC units use refrigerant to absorb the unwanted heat in a specified area and bring it outdoors until the indoor air temperature matches what you have on the thermostat.

What Does the Refrigeration Cycle Include

  • Evaporator coil: The evaporator coil's tubing is bent into a weaving pattern to expose it to airflow that comes from the blower fan. This pulls hot air from the return vent inside the home. The liquid refrigerant becomes a gas in the evaporator coil, which draws indoor heat out and cools your home. The refrigerant then cools the air through the air handler before sending it back into the house through the ducts. The refrigerant is cold at the beginning of the journey, but when it leaves the evaporator coil, it's room temperature.
  • Compressor: The compressor pumps the refrigerant fluid from the evaporator coil to the condenser. While placing the liquid under extremely high pressure, the compressor turns the refrigerant into a gas so that it can transfer heat outside through the condenser unit.
  • Condenser coil: The hot refrigerant gas travels outdoors into the condenser, where it liquefies and releases heat. Instead of trying to absorb the heat from the inside, like the evaporator coil does, the condenser fan must try to push heat away from the house. As a result, the condenser unit is often scorching, even compared to brutally hot summer days.
  • Expansion tank: The expansion tank maintains the pressure within an HVAC system to keep energy costs down and protect the efficiency of the unit. In this last component, the refrigerant loses the pressure from the compressor and condenses back into a liquid. Once it's cold again, it can begin a new cycle at the start of the evaporator coil.
New, energy-efficient evaporator coils use R410A refrigerant. Older HVAC units use harmful chemicals that deplete the ozone layer and reduce air quality. If you've had your HVAC unit for a couple of decades, consider switching to a new unit to use R410A instead of R-22.  

What Are the Different Types of Evaporator Coils?

Evaporator coils could be vertical or horizontal, and they could either have a casing or not, depending on the size and cooling capacity of your central AC unit. Consider which of these evaporator coil configurations would be best for your cooling system:
  • Vertical evaporator coil: This evaporator coil is compatible with vertical air conditioners, and it's best suited to handle an upward or downward airflow.
  • Horizontal evaporator coil: This configuration of an evaporator coil is compatible with air conditioners lying on their sides. These configurations are often easier to clean, and they take up less space, so you can install them in an attic or crawl space.
  • Cased evaporator coil: A cased evaporator coil with the metal casing is one of the most common configurations you'll most likely see in your local area. While it handles upward or downward airflow, it can also take on a horizontal shape. You would choose a cased evaporator coil over an uncased evaporator coil if the cased unit fits inside your HVAC unit and worked better during installation.
  • Uncased evaporator coil: An uncased evaporator coil is similar to the cased evaporator coil, but it doesn't have a protective case, so it's easy to customize if you have a different air conditioner. You can either place it in a vertical or horizontal position, and there's no outer metal casing covering the coils.

How Long Do Evaporator Coils Last?

Your evaporator coils should last as long as the whole HVAC system if you properly maintain them. A central air conditioning unit typically lasts between 15 to 20 years, so you can expect the evaporator coils to function that long. Most homeowners or facility managers often replace the evaporator coils if the condenser unit fails because these two units work together to provide a comfortable temperature for your home.

How Do You Maintain Evaporator Coils?

To get more out of your HVAC system, you need to keep them clean and efficient. The dust that accumulates on the evaporator coil may act as an insulator, preventing the flow of heat from one place to another. As a result, the refrigerant can't do its job, and the system will have to run longer to provide the indoor temperature you want, which means it will use more energy. On the other hand, cleaning your evaporator coils provides the following benefits for your HVAC system:
  • Reduced operating temperatures
  • Enhanced comfort throughout your whole house
  • Increased efficiency to cool your living space
  • Decreased monthly utility expenses
  • Durability for years to come
Evaporator coils are typically low-maintenance, but when you clean the entire central AC unit, you should also clean the coils to prevent system failure and reduce dirt and debris buildup.

Follow These Tips for Maintaining Your Evaporator Coils:

  • Schedule an appointment: While you could diagnose the problem yourself, an HVAC professional knows the intricacies of the system and can access the sealed coils of an air conditioning unit. Make a yearly appointment with a central air conditioning expert so your evaporator coils and HVAC system work efficiently.
  • Clean the evaporator coils: To prevent corrosion and damage, clean your indoor coils at least twice a year depending on how frequently you use your central AC unit over the summer. You could either contact an HVAC professional to clean them for you or clean them yourself. If you choose to clean them yourself, make sure you wear protective gear and provide adequate ventilation to the area in case of a refrigerant leak. Take warm water and mild detergent and apply it to the coils, allowing a few minutes for the soap to loosen debris. You can wipe the waste with a soft cloth or a soft-bristle brush.
  • Clean or replace the filter: The filter removes dust, dander and outdoor pollutants from the air that comes through the coils. If the evaporator coils become clogged, the central AC unit's efficiency could decrease. The evaporator coils must work harder to absorb the heat, resulting in more carbon emissions and higher energy bills. If the evaporator coils get dirty, the AC can also blow unclean air into your home and destroy the coils. Clean your filter at least once a month and replace it as needed.
  • Deal with corrosion immediately: The copper metal tubes that make up your evaporator coils could corrode due to humidity. If your evaporator coils show signs of corrosion,  contact an expert in the HVAC industry to help diagnose the issue. A local HVAC technician can inspect your HVAC unit and provide solutions for its care.

What Are Some Common Problems With Evaporator Coils?

You could run into several problems with your evaporator coils that could cut their life short. The following issues come from improper installation of the evaporator coil or HVAC system:
  • Selecting the wrong sizing: In a split system, HVAC contractors often undersize the evaporator coil because there's not enough room for it or they're trying to compromise for an over-sized condenser and compressor unit. At the same time, an oversized evaporator coil can reduce the suction temperature and cause frost when the outside temperature is below freezing.
  • Improper airflow: An evaporator coil might not have enough ventilation near it if the fan can't provide the air it needs to transport the refrigerant. In this case, the fan and drive package may be too small, the finned tube surface may have dirt around it or the coil's resistance could be too high.
  • Faulty expansion valve hardware: Some manufacturers of central AC units may use whatever equipment they have in stock, but they might not be using the best fit for the machine. As a result, the evaporator coil's temperature might fluctuate, and there might be too much pressure put on your AC unit, which could result in excess wear and tear.

How Do You Know When You Need to Replace Your Evaporator Coils?

Consider these warning signs that you need to replace your evaporator coils:
  • Problems with your HVAC unit: If an HVAC unit needs frequent repairs, the evaporator coil may have a couple of years at most before you need to replace it. A brand-new central AC unit could provide optimal energy-efficiency and give you a reliable evaporator coil to last for years.
  • Leaking coils: If you see any kind of liquid coming out of the evaporator coil, it means you have a refrigerant leak. Refrigerant may leak because of the corrosion of your evaporator coils. Even though R410A is eco-friendly, it's poisonous to touch and can damage your property.
  • Old age: An outdated evaporator coil might still have harmful refrigerant in it, and it most likely will need more repairs than a newer system. Change your evaporator coil for a model compatible with R410A to get the most out of it.

I Need a Coil Replacement. Where Can I Get One?

Right here, at Ingrams Water and Air Equipment! An evaporator coil is an important part of any HVAC system. We'll help you find a great one for your needs here!
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