The Hydronic Series of heat exchangers is manufactured for liquid-to-liquid applications. The counter-flow design includes an enhanced heat-exchange surface for efficient heat transfer, according to the company. Standard copper connections are directly compatible with site piping. The units are available in sizes from 50,000 to 600,000 Btus in either single or vented double-wall construction. The double-wall system prevents contamination of potable water from other nonpotable liquid circuits.

Doucette Industries Inc., P.O. Box 2337, York, PA 17405; (717) 845-8746; (717) 845-2864; www.doucetteindustries.com.