The central conditioners are also noise free and require a lot less energy even though they do a lot of work. The heating San Diego packaged air conditioners are much more or less like the central air conditioners. They are also used for multiple rooms and are to be found in huge office buildings or homes. There are also the industrial air conditioners. As the name suggests, they can easily be found in use in industrial places. They are mostly used at night to cool down soaring temperatures that may arise as result of heavy industry activities.