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.
Understanding certification and licensing can help you make informed HVAC hiring decisions. As a homeowner, hiring a technician to work on your heating, ventilation and cooling system is a task you will most likely have to do at some point. There's a great deal of danger involved with HVAC equipment and a lot can go wrong, so it's important to only hire a licensed HVAC technician for work around the home.