Copyright Goodheart-Willcox Co., Inc. Chapter 3 Boilers 57 Know and Understand 1. What is the purpose of an anode rod in a steel boiler? A. It improves boiler efficiency by adding chemicals to the water. B. It prolongs the life of the heat exchanger by consuming oxidation. C. It is a safety feature that reduces boiler water pressure. D. All of the above. 2. A Scotch Marine boiler is a _____ type boiler. A. water-tube B. fire-tube C. tube-in-tube D. None of the above. 3. At what approximate temperature does a non- condensing boiler reach its dew point? A. 110°F B. 120°F C. 130°F D. 140°F 4. What is the approximate pH of flue gas condensate? A. Between 4 and 5 B. Between 5 and 6 C. Between 8 and 10 D. Approximately 12 5. What are the three by-products of perfect combustion? A. Heat, water, and carbon monoxide B. Heat, carbon monoxide, and carbon dioxide C. Nitrogen, hydrogen, and carbon dioxide D. Heat, water, and carbon dioxide 6. What type of vent piping is normally used with a condensing boiler? A. Polypropylene B. Polyvinyl chloride C. PEX D. Both A and B. 7. True or False? Condensing boilers must be equipped with a condensate drain. 8. What are the typical low- and high-fire Btu output rates on a two-stage boiler? A. 100% and approximately 66% B. 100% and approximately 50% C. 75% and approximately 25% D. 100% and approximately 25% 9. What is the approximate efficiency of an electric boiler? A. 80% B. 90% C. 100% D. 110% 10. What effect does NOx have on the environment? A. It can react with nitrogen in the air, causing increased CO2 levels. B. It can react with organic compounds in the air, causing smog and acid rain. C. It can react with humidity in the air, causing elevated levels of greenhouse gases. D. All of the above. Apply and Analyze 1. Describe the different types of boiler classifications. 2. Explain where low-, medium-, and high-pressure boilers are used. 3. List the types of fuels and their heating content used for heating a boiler. 4. Explain why a cast-iron boiler is considered a high- mass boiler. 5. Describe the difference between a wet-base and dry- base boiler design. 6. Describe the difference between a fire-tube and water- tube type boiler. 7. Explain why a copper-tube boiler is considered a low- mass boiler. 8. What determines the AFUE of a boiler? 9. What is meant by turndown ratio? 10. Explain the operation of a mod/con-type boiler. Critical Thinking 1. Describe how a modulating boiler is similar to the gas pedal on an automobile. 2. Explain the role of a secondary heat exchanger in a condensing boiler.