For the fourth year in a row, manufacturers shipped a record number of central air conditioners and air source heat pumps in 2005, exceeding 8.6 million units, according to the Air-Conditioning and Refrigeration Institute (ARI). Shipments were up 16% from the 7.4 million units in 2004. The strong economy, continued growth in housing starts and rebuilding in the hurricane-stricken Gulf Coast all contributed to the year's record number.

ARI also reported that a total of 590,00 units were shipped in the month of December, which was due in part to a last minute flurry of shipments prior to the Jan. 23, 2006 commencement of the new 13 SEER minimum efficiency standard. Manufacturers were clearing out the remaining 10 SEER units to make room for the new models.