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5 HVAC Terms You Should Know

Electrician replacing air filter on an indoor unit

We’ve all been in situations where we nod our heads to words we don’t understand. It’s all fun and games until your HVAC unit isn’t functioning properly, and your technician uses big words to explain the situation.

The good news is that heating and cooling terms are relatively easy to understand once they’re broken down. Here is your insider on five HVAC terms you should know.


The British Thermal Unit, BTU, is a unit of measure used to measure heat. It measures the amount of energy your air conditioning uses to move heat from inside your home within an hour. The importance of understanding BTU is to help you better understand the concept of how much energy your unit uses to remove heat from the indoors to the outdoors.

According to the EIA, a single BTU (or Btu) is very small in terms of the amount of energy a single household or an entire country uses. In 2021, the United States used about 97.33 quadrillion Btu of energy.


Minimum Efficiency Reporting Value, MERV, is a measurement scale generated in by the American Society of Heating, Refrigerating and Air-Conditioning Engineers that tracks the effectiveness of air filters. A higher result in a MERV rating indicates that a filter is more efficient at capturing particles.

The importance of understanding MERV is to better understand which air filters suit you and your family’s needs best.


Air change per hour, also known as ACPH or ACH; is the air exchange rate per hour within a volume. In other words, it is how many times the air within a specific area is replaced or changed through the HVAC (heating, ventilation, and air conditioning) system. This measurement is critical in maintaining the health of the indoor air quality in your home.


Refrigerant is a compound that is found in either a liquid or gaseous state that is meant to absorb heat. During an air conditioning cycle, the refrigerant plays an important role in absorbing heat from the hot air that was cycling through the system and returning it in a cooler and colder form.

There are many problems that can happen if your refrigerant is running out. Your AC will lose its cooling power. Incorrect refrigerant levels can also lead to problems with your compressor that will jeopardize your unit from functioning.


A compressor is one of the most important parts of an air conditioning system. The compressor's job is to change the refrigerant from hot gas to a cool liquid and then back again in a repeating cycle. This allows your AC system to continually absorb heat from your home's indoor air and transfer that heat outdoors.

Providing Our HVAC Services from Los Angeles to Santa Barbara

Our specialized team at West Coast Air Conditioning is prepared to help you with all the knowledge and fundamentals you need to better understand your unit. Contact us today at (805) 954-9195 for all your HVAC needs.

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