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HVAC Terminology

The most common Heating, Ventilation & Air Conditioning terms that home and business owners should be familiar with.

HVAC, like any other industry, is full of its own terminology, jargon, and abbreviations. It’s important to be at least somewhat familiar with the language to understand the ins and outs of your home heating and air conditioning system.

Knowing how to “talk the talk” will also help you communicate with your local HVAC repair provider and really understand what is going on with your system.

In this article, we want to talk about the most common terminology in the heating and air industry and what they mean.

HVAC Tools

Air Handler

Central heating and cooling systems have two main parts, the air handler, and the condenser. The air handler is located inside your home and contains all the components needed to heat, cool, and distribute air throughout the home. It looks like a big metal box.

BTU (British Thermal Unit) Heater


BTU stands for British Thermal Unit. This is a measurement that tells you how much heating capacity a piece of equipment has. One BTU is how much heat is necessary to make one pound of water one degree Fahrenheit hotter or colder.

The higher the BTU rating, the higher the heating or cooling capacity.

Capacitors are part of the electrical system


Capacitors are part of the electrical system of your HVAC. They are used to store the energy needed to start the compressor and motor and keep them running.

Condenser coil is located in the condenser unit


Your system has two coils, one in the indoor unit, and one in the outdoor unit. The one in your indoor unit is called the evaporator coil. The evaporator coil is responsible for cooling the hot air your system pulls from the rooms in your home. The metal coil holds the chilled refrigerant which absorbs the heat from the air as it passes over it.

The Condenser coil is located in the condenser unit outside the home and does the exact opposite of the evaporator coil. When the refrigerant in your evaporator coil absorbs the heat, it is sent to the outdoor condenser unit where it is released outdoors.

condensing unit sends liquid through HVAC units

Condensing Unit

The condensing unit is the part of the system located outside of the home. It is responsible for converting refrigerant from a gas to a liquid and sending it inside to be used to cool the air.

drain pan is to collect and drain water

Photo: Cool Change Heating & Air

Drain Pan

The drain pan is the plastic or metal pan located under your air handler. As a part of the heat transfer process, water is produced by your evaporator coils. The purpose of this pan is to collect and drain that water without damaging your home.

SEER stands for Seasonal Energy Efficiency Ratio

Photo: Vardell’s Air Conditioning

SEER Rating

SEER stands for Seasonal Energy Efficiency Ratio. It is the ratio of British Thermal Units (BTU) produced to the amount of energy consumed. Homeowners shopping for new systems should be familiar with SEER ratings to help them decide which system is best for their homes. HVAC equipment with a higher SEER is more efficient but costs more up front.

Final Thoughts

We hope you found these HVAC terms useful. The more familiar you are with HVAC terminology, the better prepared you are to make the right decision for your home.

When you have your system diagnosed by a technician, it’s essential to understand what is wrong with your unit and why before spending your money on parts and repairs.

Plus, a basic understanding of the most critical components and their role in operating the system will help you better maintain your unit and guide your future purchase decisions. Learn how to keep your bedroom cooler with these simple tips.

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