List of Specific Industries
To the right, click on the [+] or [-] graphics beside an industry category to expand or collapse that list.
North American Industry Classification System (NAICS) codes for this industry
[ 238220 ] = Plumbing, Heating, and Air-Conditioning Contractors – Heating, ventilation and air-conditioning (HVAC) contractors
A half-century ago, HVAC systems were controlled by a mechanical thermostat that housed a mercury switch attached to a bi-metal temperature-sensitive spring. An extra base allowed people to manually switch between heating and cooling. Today, many homes have programmable solid state devices that provide seven-day schedules and multiple intervals for raising and lowering the temperature in the home. Specification and installation of zone controls are also common. Digital controls will inform you when to change the air duct filters and when their batteries will need to be replaced.