SMALL BOILER HEATS EFFICIENTLYThe ModCon Commercial Condensing Boiler from Heat Transfer Products features a high-grade Inconel, load-matching gas burner with a five-to-one turndown ratio to meet variable needs for space heating and domestic hot water. The boilers can be stacked two at a time; controls permit built-in redundancy for constant heat. (800) 323-9651 / www.htproducts.com.