Heating, ventilation, and air conditioning ( HVAC) is the technology, in order to provide environmental comfort of the indoors in buildings and motor vehicles. Its purpose is to provide warmth, comfort and proper air quality is linked to c, the HVAC system design is a mechanical engineering discipline, based on the principles of thermodynamics, fluid mechanics, and heat. "Cool", and sometimes to the reduction to the sphere, as HVAC&R or HVACR or" ventilation " the room, HACR (as in the designation of the circuit breaker with a HACR rated).

PLUMBING is an essential part of a well-populated structures single family houses, apartment buildings, hotels, and ancient residential houses, medium to large industrial and office buildings as skyscrapers and hospitals, vehicles such as cars, trains, airplanes, ships and submarines, as well as in marine environments, where safe and healthy building conditions are regulated in relation to the temperature and humidity of the air, fresh outdoor air.

The three major functions of heating, ventilating, and air-conditioning systems are connected to one another, especially in view of the need to provide warmth, comfort and acceptable air quality in the room, and when the reasonable costs of installation, operation, and maintenance. HVAC systems can be used in both domestic and commercial environments. HVAC systems can provide ventilation, and support for pressure is the ratio between the seats. This means that the supply and take-off of the air, is known as room air distribution.