What is the most common misunderstanding concerning conventional and condensing boilers?
It is a mistake to assume that a condensing boiler always will condense and provide more dramatic efficiency increases than noncondensing boilers, Crowley said. “With a 130˚F return-water temperature, only about 15 percent of the water vapor in flue products can be condensed,” he said. “With a 60˚F return-water temperature, about 92 percent of the water vapor in flue products can be condensed. “The degree to which a condensing boiler will return maximum efficiency is related directly to the system design,” he continued. “Unless return temperatures are very low (60 to 70˚F), the real difference in efficiency will be smaller. Also, … an operation’s seasonal changes caused by system design will affect real operating efficiency.” Another common misunderstanding is that conventional boilers do not have the ability to provide fuelburning equipment with turndown ratios comparable to those offered by condensing-unit manufacturers, Hoey said. Forced-draft-fuel-burner manufacturers produce equ
