Mechanical Engineering

Q: What is meant by equivalent length of a valve or fitting? a. its physical length at its longest dimension b. the length of a pipe that would produce the same head loss c. the length of a standard valve or fitting of the same material d. the length of the moving component in the valve

Q: A diaphragm-type expansion tank works by allowing air to be compressed. a. True b. False

Q: Why is a make-up water system necessary in a closed-loop hydronic system? a. A break in a line may occur at any time. b. The system must not be subject to unintended pressure changes. c. Fluid is designed to be expelled from the system at regular intervals. d. Small fluid losses will occur over time.

Q: How does waters flow velocity vary across a pipes diameter? a. remains constant across the diameter b. faster near the center of the pipe, and slower near the edges c. slower near the center of the pipe, and faster near the edges d. slower near the top surface, gradually increasing toward the bottom surface

Q: How much energy is needed from the circulator in a closed-loop hydronic system? a. It depends on the elevation of the system. b. It depends on the weight of the fluid. c. Enough is needed to sustain a flow rate of 2 to 4 gallons per minute. d. Enough is needed to replace the energy of head loss.

Q: Where does domestic water heating rank in terms of largest energy consumption in a typical North American home? a. first b. second c. third d. fourth

Q: What is designed to accommodate waters increase in volume in a closed-loop hydronic system? a. 3-way mixing valve b. pressure gauge c. expansion tank d. backflow preventer

Q: What is the standard unit for representing the heat transfer characteristics of a window, door, or skylight? a. unit U-value b. unit T-value c. isotherm units d. percentage of total room heat loss

Q: What is the best way to describe the compressibility of most liquids and gases? a. Liquids are compressible and gases are incompressible. b. Liquids and gases are incompressible. c. Liquids are incompressible; gases are compressible. d. A fluids compressibility depends on its specific heat.

Q: Which method is typically used to determine infiltration heat loss? a. degree day method b. average R-value method c. balanced air equations d. air change method

Q: What is static pressure? a. the pressure a fluid gains as it moves through a system b. the pressure due to the liquids own weight c. the pressure that does not change with a change in temperature in a closed system d. the pressure lost due to viscosity

Q: What is the maximum air leakage rate permitted in an Energy Star-certified house? a. 2 air changes per hour at 50 Pascals b. 4 air changes per hour at 50 Pascals c. 10 air changes per hour at 50 Pascals d. 15 air changes per hour at 50 Pascals

Q: What is the relationship between head energy and pressure in a closed-loop hydronic system? a. When head is lost, pressure increases. b. When head is gained, pressure increases. c. Both remain relatively constant. d. When head is lost, temperature increases.

Q: What rating is assigned to all electric, gas, and oil-fired storage type water heaters sold in the United States? a. peak hour rating b. first hour rating c. demand-load rating d. last hour rating

Q: In a system controlled by a high-limit controller, what is sometimes used to blend cool water returning from the heat emitters with heated water from the heat source? a. 3-way pressure valve b. 3-way mixing valve c. pressure relief valve d. make-up water system

Q: What is the best way to estimate peak hourly water demand in a household? a. Consult a DOE table. b. Make an educated guess based on the number of people in the household. c. Discuss or monitor hot water usage patterns with the occupants. d. Peak hourly water demand does not vary much between households, so a standard value may be used.

Q: How is total head calculated? a. velocity head subtracted from the viscous head loss b. equal to the amount of elevation head c. sum of velocity head, kinetic head, and static pressure d. sum of velocity head, elevation head, and pressure head

Q: What measurement is directly proportional to the R-value of a material? a. surface area of the material b. length of the material c. thickness of the material d. orientation of the material

Q: What term best describes the heat absorbed or released by a material while it remains in a single phase? a. sensible heat b. latent heat c. single-phase heat d. head

Q: An air separator should be located at the point in the system where fluid temperatures are lowest. a. True b. False

Q: What term best describes the change in density of a system fluid? a. head b. latent heat c. stratification d. coalescence

Q: Variable refrigerant flow technology used in some ductless systems adjusts flow rate based on what factor? a. zone cooling loads b. number of zones c. ambient temperature d. surface temperature of the condenser

Q: The daily usage of domestic hot water depends on which factors? a. occupancy, type of water fixtures, water pressure, and time of year b. square footage of the home, living habits, and water pressure c. peak hourly consumption, type of water fixtures, and time of day d. hot water heater capacity and its set temperature

Q: What is the best example of ducting generally used in mini-duct systems? a. 2-inch diameter fixed ducting b. 2-inch diameter flexible ducting c. large standard ducting transitioning to smaller ducting entering the condenser d. 6-inch diameter semi-rigid ducting

Q: Which term refers to the temperature contour lines found on a typical finite element analysis diagram? a. slope lines b. conduction coefficients c. resistance lines d. isotherms

Q: What is LEAST likely to be a source of VOCs? a. furnace b. furniture c. construction materials d. glass

Q: What is the typical effect of framing members that span across insulation cavities? a. Framing members reduce the effective total R-value. b. Framing members increase the effective total R-value. c. Framing members do not influence the effective total R-value. d. More framing members are generally preferred to reduce heat loss.

Q: Which of these is the most common unit of heat used in North America? a. British thermal unit b. American thermal unit c. Kilopascal d. Fahrenheit

Q: What assumption can be made when using heating degree days to estimate seasonal energy consumption? a. The number of heating degree days each month is the yearly total divided by 12. b. Heating is needed if the average monthly temperature falls below the historical average for that area. c. Heating is needed if outside air temperature drops below 65 F. d. Heating is needed if outside air temperature drops below 55 F.

Q: Which of these is the best example of a low entropy energy source? a. heat stored in a buildings graywater b. heat stored in cool outside air c. heat present in air at 65 F d. heat from a 2,500 F flame

Q: What is a practical method to measure the airtightness of an existing or partially-constructed building? a. blower door testing b. exhaust rate testing c. window seal testing d. inspecting windows for cracks

Q: Which is a side effect of a powered exhaust system? a. pressurization of the building b. depressurization of the building c. increase in humidity in the building d. decrease in humidity in the building

Q: What is the first step in designing a space heating system? a. Select the primary fuel source. b. Calculate the design heating load of each room. c. Determine whether renewable energy sources will be used in a primary or auxiliary fashion. d. Estimate the airtightness of the building based on construction quality.

Q: Graywater heat exchangers should be installed on drainage pipes that run in which orientation? a. horizontal only b. vertical only c. diagonal d. either horizontal or vertical

Q: When applying the degree day method, what correction factor is used to compensate for the effect of internal heat gains and warm-weather degree days? a. delta T b. Cd c. Dd d. K

Q: Thermal radiation is electromagnetic energy. a. True b. False

Q: According to Robert Bean, all of the factors below determine indoor environmental quality EXCEPT ____. a. thermal comfort quality b. odor quality c. vibration quality d. visual quality

Q: How do you determine the total R-value of a composite (made up of several materials) assembly? a. Add the individual R-values. b. Add the individual R-values and divide by the number of materials. c. Add the inverses of the individual R-values. d. Add the individual U-values.

Q: The primary method of heat loss from a human being is conduction to the surrounding air. a. True b. False

Q: What is an unlikely effect of a leak or drip in a hot water piping system? a. increased thermal load b. decreased thermal load c. wasted water d. annoyance

Q: Supplying existing thermal loads with renewable energy sources usually provides a better return on investment than reducing loads. a. True b. False

Q: Which energy source is NOT considered a form of conventional energy? a. natural gas b. propane c. fuel oil d. hydroelectric

Q: The unit cost of an energy source is independent of the device used to convert that energy into heat. a. True b. False

Q: Which example is NOT an energy-efficient construction method? a. framing that reduces thermal bridging b. fully taped building wrap over sheathing c. low R-value insulation in crawl spaces d. 24 inches on center inline framing

Q: The main purpose of installing a heating system is to maintain human comfort. a. True b. False Indicate the answer choice that best completes the statement or answers the question.

Q: An advantage of using heating load estimating software is that calculations may be saved for future use. a. True b. False

Q: How does the body respond to a decrease in convection heat loss? a. lowering internal body temperature b. increasing perspiration c. reducing skin temperature d. it does not respond

Q: All building surfaces that separate heated space from unheated space are known as the thermal barrier. a. True b. False

Q: Which factor was LEAST influential in increasing the current interest in alternative energy sources? a. government incentives b. concern about global climate change c. change in the price of crude oil in the 1980s d. increasing demand for conventional energy beginning in 2007

Q: Air film resistance represents the insulating effects of thin layers of air that cling to all surfaces. a. True b. False

Q: Which of these is the primary driving force that causes heat to move? a. thickness of the materials that store heat b. form of the heat (solid, liquid, or gas) c. temperature difference d. volume of air contained in a building

Q: A typical slab-on-grade foundation loses more heat to the ground below than to the air at the exposed edges of the slab. a. True b. False

Q: What is the best example of flooring material with high thermal mass? a. concrete b. cork c. wood d. carpet

Q: Materials with higher R-values conduct heat more slowly than materials with lower R-values. a. True b. False Indicate the answer choice that best completes the statement or answers the question.

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