ARLINGTON, Va. — The Air-Conditioning, Heating, and Refrigeration Institute (AHRI), an HVAC manufacturers association, has released the year-to-date and monthly shipment numbers for HVAC equipment.

Year-to-date, U.S. shipments of gas warm air furnaces increased 16 percent to 2,601,760 units, and the combined central air conditioners and air-source heat pumps were up 9.9 percent to 6,169,700.

Although the year-to-date numbers finished above 2012 for these categories, the monthly numbers for December 2013 experienced some fluctuation. Warm air furnaces increased 17.4 percent but oil warm air furnace shipments declined 8.2 percent. Overall, 2013's oil warm air furnace shipments decreased a total of 10.7 percent to 32,144.

December's U.S. shipments of air conditioners and air-source heat pumps increased 8.2 percent. Air conditioners alone were up 2.3 percent and air-source heat pumps increased 19 percent in December 2013.

For more information, visit www.ahrinet.org.