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Understanding the Refrigeration Cycle

As a homeowner, it can be helpful to understand the basics of how the various systems in your home work. Case in point: the refrigeration cycle. This is the cooling cycle that your central air conditioner or heat pump goes through multiple times a day during warm weather to increase your home comfort.

What Is the Refrigerant Cycle?

The refrigerant cycle is the circuit that refrigerant makes through your system’s refrigerant lines and through the heat transfer process to cool your home. Successful completion of the refrigerant cycle is crucial to your comfort in the hotter months. It’s important to note that the refrigerant cycle removes heat from your home, therefore making it feel cooler.

To understand the basic cycle of refrigeration in your HVAC system, it helps to know the various components of the system and how they work together in the AC refrigeration cycle.

Components of the Refrigerant Cycle

The cooling/refrigerant cycle has four fundamental components – the compressor, the condenser, the expansion valve, and the evaporator. Each has a specific job in the HVAC refrigeration cycle. Let’s take a look.

1. Compressor

The compressor is the heart of your cooling system. It’s located in the outdoor unit and it pressurizes and circulates refrigerant through your HVAC system. Without the compressor, no cooling would happen. The refrigerant enters the compressor as a low-pressure gas. The compressor compresses it into a high-pressure heated gas and moves it through the discharge line and on to the condenser.

2. Condenser (Condenser Coil)

The condenser is also located in the outdoor air conditioning unit or heat pump. The refrigerant enters the condenser as a gas and passes through the condenser coil which condenses the gas to a vapor and then to liquid form and releases heat into the outside air.

3. Expansion Valve

The high-pressure liquid then moves to the expansion valve. By restricting the fluid flow, the valve lowers the pressure before the liquid refrigerant moves to the evaporator.

The expansion valve acts a lot like the button on a can of a keyboard air duster. You’re releasing high-pressure air inside the can, and that rapid expansion makes the air cold.  The same thing happens when the expansion valve releases the high-pressure refrigerant into the evaporator, the evaporator coil is cooled by the expanding refrigerant.

4. Evaporator

Next, the liquid refrigerant enters the evaporator. The evaporator coil is inside your home, and it has a big job. It absorbs the heat from inside your home and turns the liquid back into a gas. The heated gas then moves to the compressor, and the refrigerant cycle starts again.

To break it down further, a refrigeration cycle has a hot coil and a cold coil.  The hot coil is called the condenser, and the cold coil is called the evaporator.  In the summertime, the air is blown across the cold coil (the evaporator) which is inside your home.  That cooled air is what keeps you comfortable in the summer heat! 

In the wintertime, heat pumps have a unique ability that air conditioners do not have. They can re-route the refrigerant flow inside the refrigeration system, and make the coil inside your home become the hot coil (the condenser), so that now as the air in your home blows across the coil is it heated up, keeping your house warm.  

If you think about it, you experience this every day with your refrigerator.  The cold coil keeps the air inside the refrigerator cold, and if you’ve ever felt the slight warm breeze of air coming from the vents at the bottom of the fridge, that is the warm coil that sits under the refrigerator giving off heat.

Common Issues Affecting the Refrigerant Cycle

Common (and not so common) problems in the HVAC refrigerant cycle can cause your air conditioner or heat pump to struggle or even fail to cool your home. Some issues include:

  • Low refrigerant
  • Refrigerant leak
  • AC blowing warm air
  • Dirty coils
  • Frozen evaporator coil
  • Short cycling
  • High energy consumption
  • And more

Regular AC maintenance can help you avoid some of these issues. If you’re having trouble with your central air conditioning or heat pump cooling, contact a reliable HVAC company for help. You can also view our AC troubleshooting guide for more tips.

Importance of Proper Refrigerant Management

It’s important to schedule regular air conditioning maintenance of your outdoor AC unit or heat pump. Regular maintenance will keep your cooling system running at peak performance.

During an AC tuneup, the HVAC technician will check for refrigerant leaks, address the problem if there is one, and recharge refrigerant as needed. Refrigerant leaks can be harmful to the environment as well as your wallet. They should inspect all of the refrigerant cycle components as well as wiring and your thermostat to help ensure your cooling system maintains the temperature you desire.

Read our AC maintenance tips for more information on keeping your system in great shape.

Questions about your HVAC system? Check out our resources guide, or contact a local technician.

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