Alternative Energy Demystified, 2nd edition

Stan Gibilisco

Explanations for Quiz Answers in Chapter 2

1. All three of the choices A, B, and C hold true when we compare an indoor circulation intake with an outdoor circulation intake, so the answer is D, "All of the above." We mustn't confuse the circulation intake with the combustion intake, however. In a forced-air heating system, the air for the combustion normally comes from the outside. This air doesn't contribute to the air flow in the house. If the combustion intake is located indoors, it will create negative pressure inside the house, causing cold outdoor air to enter wherever a leak exists in the structure. That effect will reduce, not improve, the overall system efficiency. Once again, as this question is stated, the correct response is D.

2. A humidifier will increase the amount of water vapor in the air, a well-known tactic that can help to reduce annoying electrostatic buildup, also called "static electricity." Centrifugal switches and inducers have nothing to do with electrotatic charge buildup, so choices A and B won't work. Forced-air heating systems don't have catalytic converters, so choice D won't work either. The correct choice is C.

3. Propane doesn't dissolve in water, so it presents relatively little risk to water supplies. Propane can soak into the ground to some extent, although it tends to vaporize rapidly. Propane can leak from tanks (as any liquid or gas can escape from a faulty tank). Propane can certainly escape into the air if a tank leaks. The correct choice is A.

4. When hydrogen burns, you get heat and water vapor, and nothing else at all. Only choice C correctly completes this statement.

5. Liquid petroleum (LP) gas generally consists of propane, but in some places, suppliers add butane as well. Oxygen, hydrogen, and methane gases are not deliberately added to LP gas. (We might note, in passing, the fact that hydrogen is bound up in propane and butane atoms, as is carbon. But LP gas contains neither hydrogen nor carbon in elemental form. The hydrogen and carbon together form the hydrocarbon compounds C3H8 and C4H10, which we call propane and butane, respectively.) The answer is D.

6. If a steam radiator springs a leak, the steam will come out and make a hiss or squeal that you can't miss. (Sometimes it sounds like a teapot or a pressure cooker.) You won't smell ethyl mercaptan, because the steam in a radiator type system doesn't contain any of that. You won't sense any decrease in the humidity; in fact, technically, the water vapor that comes out of the radiator will slightly increase the humidity in its vicinity. The correct choice is C.

7. Once the steam has passed through the radiators and given up energy to the surrounding air, it condenses into liquid water and returns to the furnace boiler, which heats it up to form steam again for another cycle. The answer is B.

8. Oil, which remains in the liquid state even when not stored in tanks, can't normally explode as methane can. This property makes oil generally safer to handle than methane or even propane. The correct choice is C. (By the way, the other three choices here are not only incorrect, but patently false!)

9. A hot-water heating system does not require any blower to circulate the warmed air throughout the house, so the system doesn't increase or decrease the air pressure inside the house. (The system might have a combustion air intake fan and an exhaust vent, but these normally come from and return to the outside, so they don't affect the indoor air pressure.) The correct choice is A.

10. In an oilheat furance, the device that atomizes the fuel (breaks it into fine particles that mix with incoming air to form a flammable mist) works in the same way that a carburetor atomizes the fuel in a motor vehicle. The answer is D.