This book mainly introduces the design, selection, installation and troubleshooting of the currently popular home and commercial central air conditioners, which involve multi-split air conditioners, water-cooled heat pump water type central air conditioner, ducted household central air conditioner, VRV variable frequency control household and commercial central air conditioner, water source heat pump central air conditioner, ground source heat pump central air conditioner, water-cooled household air conditioner and small absorption central air conditioner.