One of the widest uses of heat exchangers is for air conditioning of buildings and vehicles. This class of heat exchangers is commonly called air coils, or just coils due to their often-serpentine internal tubing. Liquid-to-air, or air-to-liquid HVAC coils are typically of modified crossflow arrangement.

A clean, unobstructed dryer vent improves the safety and efficiency of the dryer. As the dryer duct pipe becomes obstructed and filled with lint, drying time increases and causes the dryer to overheat and waste energy. In extreme cases, a blocked vent may result in a fire. Clothes dryers are one of the most costly appliances in your home to operate.

If the tap water contains a lot of minerals, also known as hard water, then the ultrasonic or impeller humidifiers will produce a "white dust" (calcium is the most common mineral in tap water), which usually spreads over furniture, and is attracted to static electricity generating devices such as CRT monitors. The white dust can usually be prevented by using distilled water and a demineralization cartridge in ultrasonic humidifiers.

For the last 20 to 30 years, manufacturers of HVAC equipment have been making an effort to make the systems they manufacture more efficient. This was originally driven by rising energy costs, and has more recently been driven by increased awareness of environmental issues. In the USA, the EPA has also imposed tighter restrictions. There are several methods for making HVAC systems more efficient.

DIn May 1999, the North American Insulation Manufacturers Association began implementing a comprehensive voluntary work practice partnership with the U.S. Occupational Safety and Health Administration (OSHA). The program, known as the Health and Safety Partnership Program, or HSPP, promotes the safe handling and use of insulation materials and incorporates education and training for the manufacture, fabrication, installation and removal of fiber glass, rock wool and slag wool insulation products.