HVAC technicians have an important job and must balance a variety of factors before beginning an installation project. They have to look at installation cost, efficiency, and maintenance and compare that to the needs of a client and how different installation type will provide comfort. Whether the HVAC unit will go in a home, office building, or a controlled test laboratory all impact the needs of the clients and what systems are suitable.
In this field, there are many acronyms and specialized terms which every HVAC technician must be familiar with. The level of complexity is one of the reasons why special education is needed before someone becomes an HVAC technician.
A variable-speed motor, for example will change its speed to adapt itself to the need of the installation location. Because it runs at a lower speed most of the time, these units are quieter than other models. It circulates air constantly which removes humidity as well as eliminates the all to well known start up sound.
BTUs, or British thermal units, are familiar in industries beyond HVAC. Without going into the exact mathematics behind this system of measurements, it can be thought of as the amount of energy needed to bring the temperature of a pound of water by one degree Fahrenheit. It is equal to 1055 joules. Joules are used instead of BTU’s in many countries outside of the the United States. Just to give a general idea, a four inch long wooden match stick will produce 1 BTU. A joule is a derived unit of energy. The higher the BTUs of a system, the stronger the heat output will be.
One of the ways in which an HVAC technician helps their clients keep the costs down is through the process of enthalpy. The heat content of a sample of air is measured. This amount is figured by adding the heat energy of the dry air plus the heat energy of the water vapor. By figuring this out, an HVAC technician can find out how much air from the outside can be brought into a house and recirculated.
To determine efficiency, the efficiency of the filter is factored in. The Minimum Efficiency Reporting Value (MERV) relates to how large or small the holes in an air filter are. The size of the holes control how much air will flow through the filter. Smaller holes within a filter are more efficient and will thus have a higher MERV rating.
A filter with a MERV rating of 20, the highest rating, are 99.99% effective and will eliminate this percentage of unwanted particles from the air. Filters with this rating are typical used in clean rooms. In the most common homes, the filters will have a MERV rating of 3. From here, level of about 7 or 12 are used for higher end housing.
There are hundreds of terms within the HVAC world that are trade specific. It is like learning a new language. These terms give credit to the depth of training and education that these technicians must achieve. It is not something that one would just wake up and start doing. It takes dedication to develop the vocabulary which will make them successful.