Commercial condensing boilers cost one and a half times as much as conventional boilers of similar size, but their high efficiency—especially at part load where boilers operate most of the time—lets you recoup that cost premium quickly. The key to realizing these savings is matching the boiler to a properly designed low-temperature heat distribution system. Understanding the competing efficiency metrics and the interactions within the larger boiler system will help you ensure that an effective system is installed. The use of condensing boilers is on the rise; they comprise a market share of nearly 25 percent of current boiler sales.