Carrier brand air conditioners, including 4-ton capacity models, are available for purchase from local heating, venting and air conditioning (HVAC) dealers. Additionally, these dealers typically install and troubleshoot the operation of new systems.
Carrier brand 4-ton air conditioning units can also be purchased from online sellers such as AC Wholesalers and Amazon.com. Purchased standalone units are sometimes cheaper but don't feature a manufacturer's warranty or include installation. These units are a cost-effective alternative to higher-priced units from factory-authorized dealers.
A 4-ton AC unit has a cooling capacity of 48,000 British thermal units, commonly referred to as BTUs. Generally, the 1-ton of capacity is equivalent to 12,000 BTUs. This measurement dates from when ice blocks were used to cool buildings. One ton of ice, melting uniformly, pumped approximately 12,000 BTUs of heat out of the affected area per hour.