ESSEN, Germany — Mini-split air conditioning may never have such a large impact on the U.S. comfort cooling industry as they have had in Europe. But a look at what makers of such equipment were talking about at the most recent International Trade Fair for Refrigerating and Air Conditioning (IKK) here can give some idea of a/c trends.

Manufacturers were stressing that the latest products are among the quietest ever made. And for the time being, R-407C still is preferred over R-410A.

Long-time refrigerant R-22 now is barely making a blip on the mini-split screen.

The refrigerant issue is in a state of flux. Manufacturers initially preferred R-407C because it was easier to modify previous technology for that new refrigerant. But at least one refrigerant producer predicted use of R-407C would level off in Europe in 2005, at which time R-410A would become the air conditioning refrigerant of choice.

He said one reason will be manufacturers completing redesigns of air conditioners that will work with R-410A.

Along with refrigerant preference, companies discussed the quietness of their mini-splits.

An example of the quiet talk came from Mitsubishi Electric, which proclaimed that the newest models in the RV Series run at 26 to 29 dB, billed as “the quietest operation in the industry.” The company claims “sound has been decreased by more than 50%.”

It was done in part, the company said, by modifying the positioning of the heat exchanger to make airflow smoother, while an increase in fan diameter produces larger airflow volume at lower fan speeds.

The company Electra noted that its Inverter model is now being made available worldwide. The unit features an inverted compressor to optimize temperature control.

A unit from UKT employed three ventilation speeds for quieter runs.

And Tadiran promoted its split system for both commercial and residential applications. The units have room control units that are designed to determine the quality of airflow supplied to each room, all controlled by personal remote control units through opening and closing of the damper’s louvers.