There are three distinct types of muscles: skeletal muscles, cardiac or heart muscles, and smooth (non-striated) muscles.
HVAC technicians are responsible for the installation, maintenance and repair of heating, ventilation and air conditioning (HVAC) systems. As an HVAC technician, your job duties may include inspecting existing systems and making recommendations intended to improve the efficiency and/or safety of that system's performance. HVAC-R techs may also work on refrigeration systems.
How Long it Takes for HVAC Certification. HVAC technicians repair and install air conditioning and heating units in homes and offices. Heating, air conditioning and ventilation -- or HVAC -- technicians are in demand. The Bureau of Labor Statistics estimates that jobs for HVAC technicians will grow 34 percent by 2020, which is much faster than average than other industries.