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.
By providing a climate controlled environment, refrigeration systems make it possible to store and transport food, medicine, and other perishable items. Although trained to do all three, HVAC technicians sometimes work strictly with heating, air conditioning, or refrigeration systems. They also may specialize in certain types of HVAC equipment, such as water-based heating systems, solar panels, or commercial refrigeration.