This fluid is compressed and expanded to both provide indoor heating by transferring warmth or out of doors cooling by dissipating heat. Vents/Registers: Vents and registers are opening in walls, floors, or ceilings wherever conditioned air enters rooms and where return air is collected. Refrigerant: Utilized in air conditioning methods https://hvac30515.bloguetechno.com/the-basic-principles-of-hvac-67857051