These losses are determined by the boiler skin temperature, amount of surface area, and ambient conditions. These five factors form the basis for comparing boiler fuel use. Comparing them with the stated efficiency value lets you understand efficiency values more thoroughly and compare them more effectively. The comparison, however, is useful only if combined with a comparison of boiler design. For example, if two boilers are stated as operating at the same stack temperature and one has less heating surface, stack temperature on the boiler with less heating surface should be challenged.
Efficiency is a complex issue.
Many factors influence boiler efficiency and stated values can be interpreted in various ways by vendors. The bottom line is to examine the five factors used in the efficiency calculation, then work with vendors who can point to projects where the stated efficiencies and stack temperatures are realized. Once a boiler is purchased, it is difficult to reverse the decision. Performing basic research before you buy provides the highest efficiency boiler and the maximum return on your investment. Verifying Efficiency Verifying efficiency comes down to answering four questions.