For the past three years, central air conditioner and heat pump shipments have dipped in April and the trend appears to be continuing in 2008, according to statistics from AHRI.

Furnace and water heater shipments for the year-to-date are down, compared with the same four-month period a year ago.

The Air-Conditioning, Heating and Refrigeration Institute found that combined U.S. factory shipments of central air conditioners and air-source heat pumps for April totaled 524,296, down 6 percent compared with the same month a year ago. For the year-to-date, combined shipments totaled 1.8 million, a 7 percent drop compared with the same period last year.

Heat pump shipments for April totaled 149,287, down 9 percent from the same month a year ago. For the year-to-date, heat pump shipments totaled 584,618, a 5 percent drop.

U.S. factory shipments of gas-powered warm-air furnaces in April totaled 136,561, a 19 percent drop compared with the same month a year ago. Oil warm-air furnaces for the same month totaled 2,738, a 28 percent drop compared with April 2007 totals. For the year to date, gas furnace shipments totaled 664,714, a 17 percent drop compared with the same period last year. Oil furnace shipments for the year-to-date totaled 16,448, a 27 percent drop compared with the same period last year.

A total of 4,225 vent-free room heaters were shipped in April, a 45 percent increase compared with the same month last year. For the year so far, 16,654 units have been shipped, a 2 percent drop compared with the same four-month period last year.

Residential electric water heater shipments for April totaled 348,596, a 3 percent drop from the same month a year ago. Residential gas water heater shipments totaled 341,935, a 7 percent drop compared with shipments for the same month last year. For the year, 2.8 million residential gas and electric storage water heaters have been shipped, an 8 percent drop.

Commercial gas water heater shipments for April totaled 8,134, jumping 15 percent compared with the same month last year, while commercial electric water heater shipments totaled 6,013, jumping 18 percent compared with the same month a year ago. For the year, electric water heater shipments are 7 percent ahead of total shipments of this product during the same period last year. Commercial gas water heater shipments for the year-to-date are up 2 percent, compared with the same period a year ago.