HVAC (heating, ventilating, and air conditioning; also heating, ventilation, and air conditioning) 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, (heating,ventilating and air-conditioning & Refrigeration) or ventilating is dropped as in HACR (such as the designation of HACR-rated circuit breakers).

HVAC is important in the design of medium to large industrial and office buildings such as skyscrapers, onboard vessels, and in marine environments such as aquariums, 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, and carbon dioxide. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, and prevents stagnation of the interior air.

Heater is an object that emits heat.

Heater may also refer to:

In electronics:

In music:

In other fields:

Targetmaster is a subline of the Transformers toyline that include Nebulan sidekicks who can transform into the Transformers' weapons.

1987 Targetmasters

The first Targetmasters assortment, released in 1987, included six new characters, and five existing ones from the 1986 line, whose toys were slightly remolded with larger peg holes to hold their new weapons, as well as an additional peg hole for each remold to mount its weapon in vehicle mode. In 2003, one of the two Japanese-exclusive Targetmasters from 1987 was added to the Autobot ranks. Unfortunately, the Targetmaster weapon he shares with Decepticon Cyclonus, also share names. To further add to the confusion, the printed names of Stepper and Artfire's weapon/partners in Japan are swapped. Cyclonus's partner Nightstick is called Nebulon (the name Fracas is erroneously given on Scourge's box) and paired with Stepper. Scourge's partner Fracas is called Nightstick and paired with Artfire.

The smaller Targetmaster partners were easily lost making them highly collectable and demand high prices on the secondary market.