High efficiency boilers were introduced in response to the energy crisis of the seventies. Most first generation highefficiency boilers were simply standard units that had been hurriedly modified to boost efficiency. These boilers obtained higher efficiencies by permitting steady-state condensation in the heat exchanger and in the combustion chamber.Failure to adequately protect the combustion chamber and heat exchanger from the corrosive effects of condensate meant that most first generation units failed prematurely. The units condensed, eventually corroded, and finally were discarded.Manufacturers learned from their mistakes. They upgraded materials, redesigned heat exchangers and refined their manufacturing techniques. The second generation of high efficiency boilers, which began to appear in the late eighties, was a vast improvement. However, second generation units still experience damage from condensation. Although the materials used in second generationhigh efficiency boilers last considerably longer, they still eventually succumb to corrosion.

Clickable Parts Diagram

ADB Manual (Acrobat Reader Required)