Class 5 Boiler Practice Exam 2025 - Free Boiler Certification Practice Questions and Study Guide

An economizer serves the important function of recovering heat from the flue gases that result from combustion in the boiler. The heat extracted is then used to preheat the feedwater before it enters the boiler. This process improves the overall efficiency of the boiler system by utilizing waste heat that would otherwise be lost, thus reducing fuel consumption and enhancing energy efficiency.

By preheating the feedwater, the economizer decreases the amount of energy needed to bring that water up to the temperature required for steam generation. This not only helps in saving operational costs but also contributes to more efficient thermal management within the boiler system.

Other options focus on different functions that do not align with the primary role of an economizer. For example, cooling flue gases is typically managed by other components designed specifically for that purpose, while increasing boiler pressure is a function of the boiler's operating conditions and not directly related to the economizer's function. Lastly, removing impurities from fuel pertains to fuel treatment processes, which is separate from the economizer's heat recovery function.