Heating, ventilation and air conditioning (HVAC) is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. Refrigeration is sometimes added to the field's abbreviation as HVAC&R or HVACR, or ventilating is dropped as in HACR (such as the designation of HACR-rated circuit breakers).

HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels and senior living facilities, medium to large industrial and office buildings such as skyscrapers and hospitals, onboard vessels, and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors.

Ventilating or ventilation (the V in HVAC) is the process of exchanging or replacing air in any space to provide high indoor air quality which involves temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide, and other gases. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, and prevents stagnation of the interior air.

The items used in HVAC systems are :

  • Temperatue & Humidity
  • Differential Pressure
  • Air Velocity sensors
  • Recorder

Temperature & Humidity Sensors

Humidity sensor, measures and reports the relative humidity in the air. It therefore measures both moisture and air temperature. Relative humidity is the ratio of actual moisture in the air to the highest amount of moisture that can be held at that air temperature. The warmer the air temperature is, the more moisture it can hold.

Humidity sensors can be used as a monitoring and preventive measure in homes for people with illnesses that are affected by humidity. They are also found as part of home heating, ventilating, and air conditioning systems (HVAC systems). They can also be found in offices, cars, humidors, museums, pharmacy, industrial spaces and greenhouses and can be used in meteorology stations to report and predict weather.

Temperature sensor is a sensor used to detect heat exchange / temperature changes in a dimension of a particular object or dimension of space.

Product example :

bahan  Rotronic HygroFlex1 – HF1 – inexpensive HVAC transmitter (click image for detail)

phpThumb_generated_thumbnailjpg  Autonic THD-DD1-C (click image for detail)

Differential Pressure transmitter

The most common and useful industrial pressure measuring instrument is the differential pressure transmitter. This equipment will sense the difference in pressure between two ports and produce an output signal with reference to a calibrated pressure range.

Product example :

1  Dwyer Series MS Magnesense Differential Pressure Transmitter (click image for detail)

Air Velocity Sensors

Air velocity sensors can be measured by sensing the pressure produced by the movement of the air.

Product example :

12  Dwyer Series 641 Air Velocity Transmitter (click image for detail)


In this case, recorder is a tool used to record every activity that occurs in the HVAC process.

Product example :

phpThumb  Autonic KRN100 Series (click image for detail)

Ilustration of HVAC