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.
Job Duties. The job duties of a general laborer vary. They may include cleaning and preparing a job site, loading and delivering materials, and using a variety of tools and machines such as blowtorches, forklifts, levels, lifts, power drills, grinders, saws, pressure washers, and water spraying equipment.