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HVAC CDC's > Volume 2 > Flashcards

Volume 2 Flashcards

1
Q

(201) What affect will dust on fan blades have on heat transfer?
a. It will reduce heat transfer.
b. It will increase heat transfer.
c. It will maintain heat transfer.
d. It will add heat to due latent heat in the dust.

A

a. It will reduce heat transfer.

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2
Q

(201) Where do you view the rotation and discharge of a centrifugal fan?
a. Looking from above.
b. From behind the fan.
c. On the pull side.
d. On the drive side.

A

d. On the drive side.

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3
Q

(201) Why are vanes used in the vane axial fan?
a. To decrease total duct pressure.
b. To increase total duct pressure.
c. To cause turbulence of the straight moving air.
d. To straighten out the spiraling motion of the air.

A

d. To straighten out the spiraling motion of the air.

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4
Q

(201) What will allow a sheave to be used on different diameter shafts?
a. Shafts.
b. Bearings.
c. Bushings.
d. Shaft thinner.

A

c. Bushings.

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5
Q

(201) Where will the classic V-belts (A through E) be used?
a. Medium horsepower applications.
b. Low horsepower applications.
c. High horsepower applications.
d. The highest of all horsepower applications.

A

a. Medium horsepower applications.

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6
Q

(201) If you have four belts and one is bad, how many should you replace?
a. 1.
b. 2.
c. 3.
d. 4.

A

d. 4

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7
Q

(202) In a single-duct unit, why is the manual damper left in its initial position?
a. To provide a constant pressure decrease.
b. To provide a constant pressure increase.
c. To maintain a constant airflow through the box.
d. To vary the amount of airflow that is allowed through the box.

A

c. To maintain a constant airflow through the box.

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8
Q

(202) Which design(s) do multiple-path systems use?
a. Multiple cooling duct boxes or a separate supply duct to each zone.
b. Single-blended variable boxes for variable flow.
c. Separate cold- and outside-air duct distribution systems or single-blended variable boxes.
d. Separate cold- and warm-air duct distribution systems or separate supply duct to each zone.

A

d. Separate cold- and warm-air duct distribution systems or separate supply duct to each zone.

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9
Q

(202) Why are multi-path, multi-zone systems limited to smaller areas?
a. Because of the dual-duct design.
b. Because the fans on these systems are weaker.
c. Because of the multiple runs of single-zone ducts.
d. Sheet metal does not come in any larger sizes for these systems.

A

c. Because of the multiple runs of single-zone ducts.

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10
Q

(202) If a cooling demand is reduced in a building, what will the supply dampers do?
a. Begin to close.
b. Begin to open.
c. Open 100 percent.
d. Shut immediately.

A

a. Begin to close.

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11
Q

(202) What is one reason for the use of terminal reheat?
a. To only control the temperature.
b. Terminal reheat is used in every HVAC/R system.
c. Make up for steady temperatures around the perimeter of a building.
d. Allow zone or space control for areas of unequal loading.

A

d. Allow zone or space control for areas of unequal loading.

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12
Q

(202) What makes an independent variable air volume (VAV) system truly independent?
a. They can control the maximum and minimum cfm that can be supplied from the box.
b. It is controlled by the main duct static pressure sensor.
c. They rely on the static pressure in the primary air duct.
d. It has no physical connections to the primary air duct.

A

a. They can control the maximum and minimum cfm that can be supplied from the box.

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13
Q

(203) How do you prevent carryover into the ductwork while using atomizing sprays?
a. Using an adsorbent.
b. Using velocity pressure.
c. Using static pressure.
d. Using an eliminator or filter.

A

d. Using an eliminator or filter.

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14
Q

(203) When is the use of a return air system generally essential?
a. On smaller systems.
b. On larger systems.
c. On medium systems.
d. On every HVAC/R system.

A

b. On larger systems.

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15
Q

(203) What is the result of a dirty or clogged filter?
a. Resistance to flow and reduced efficiency.
b. Increased airflow and reduced efficiency.
c. Decreased airflow and increased efficiency.
d. Increased heat transfer.

A

a. Resistance to flow and reduced efficiency.

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16
Q

(203) What causes the adjacent blades on an opposed-blade damper to move in opposite directions?
a. A linkage.
b. Load wiring.
c. A volume damper.
d. The parallel design.

A

a. A linkage.

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17
Q

(204) What does carbon monoxide combine with to interfere with the oxygen supply?
a. Tobacco smoke.
b. Other air pollutants.
c. Hemoglobin.
d. White blood cells.

A

c. Hemoglobin.

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18
Q

(204) What will affect a person’s sensitivity to an odor?
a. Time of the year.
b. White blood cells.
c. Temperature and humidity.
d. Time of the day or time of year.

A

c. Temperature and humidity.

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19
Q

(204) What can make locating an indoor air quality issue difficult?
a. Static pressure.
b. High velocity pressure.
c. The different sensitivities of people.
d. An overwhelming amount of trouble calls.

A

c. The different sensitivities of people.

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20
Q

(205) How can air be cleaned?
a. By cleaning the condensate drain of debris.
b. By filtering the air and cleaning the ductwork.
c. By reducing static pressure to cause particles to fall out of air.
d. By increasing the velocity pressure to eliminate particles.

A

b. By filtering the air and cleaning the ductwork.

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21
Q

(205) What should be considered while planning the ventilation for odor control?
a. The number of occupants in the facility.
b. Decreases in heat load and the availability of air of inadequate quality.
c. Decreases in heat load and the availability of air of adequate quality.
d. Increases in heat load and the availability of air of adequate quality.

A

d. Increases in heat load and the availability of air of adequate quality.

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22
Q

(206) When would the greatest pump lift possible occur?
a. With the biggest pump possible.
b. When there is the minimum water flow possible.
c. If there were a perfect vacuum at the pump suction.
d. If there perfect pump discharge conditions.

A

c. If there were a perfect vacuum at the pump suction.

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23
Q

(206) What may cavitation cause?
a. Pitting and extremely high discharge pressures.
b. Pitting and wearing of the impeller.
c. Pitting and wearing of seals.
d. Pitting and vortex.

A

b. Pitting and wearing of the impeller.

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24
Q

(207) What should be done if a stuffing box leaks too much?
a. Lubricate the bearings.
b. Seal the packing with grease.
c. Tighten the stuffing-box gland.
d. Tighten the mechanical seal.

A

c. Tighten the stuffing-box gland.

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25
Q

(207) A leaking seal is replaced when the fluid leakage rate exceeds
a. 1 drop per minute.
b. 3 drops per minute.
c. 5 drops per minute.
d. 7 drops per minute.

A

c. 5 drops per minute.

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26
Q

(207) What should you check when you are making major repairs on a pump?
a. Static head.
b. Suction lift.
c. Total static head.
d. The performance of the pump.

A

d. The performance of the pump.

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27
Q

(208) In a series loop system, how does unit output change from the first to last unit?
a. It stays uniform throughout.
b. It gradually lowers.
c. It quickly lowers.
d. It gradually increases.

A

b. It gradually lowers.

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28
Q

(208) What is required for one-pipe down feed units to overcome thermal head?
a. Two special fittings.
b. Three special fittings.
c. Two check valves.
d. Three check valves.

A

a. Two special fittings.

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29
Q

(208) Why does a direct return system need to be more carefully balanced?
a. Because the check valves cause uneven flow.
b. Because all the units have the same flow rate.
c. Because of the special tees installed.
d. Because there are different flow rates.

A

d. Because there are different flow rates.

30
Q

(209) Where should radiators be located?
a. Where heat loss is the greatest.
b. Where heat loss is the least.
c. Where there is no heat loss.
d. Where there is the greatest heat gain.

A

a. Where heat loss is the greatest.

31
Q

(209) What does the square feet of equivalent direct radiation depend on?
a. The piping to the radiator.
b. The supply piping to the radiator.
c. Radiator capacity and configuration.
d. Radiator location and configuration.

A

c. Radiator capacity and configuration.

32
Q

(209) What effects are caused by air binding in a piping circuit?
a. Noise and reduction in flow.
b. Increased heat transfer.
c. Increased system efficiency.
d. Air kept where it needs to be.

A

a. Noise and reduction in flow.

33
Q

(209) What flow arrangement should be used when hot water coils are used with freezing temperatures?
a. Four pipe versus three pipe system.
b. Three pipe versus four pipe system.
c. Parallel-flow rather than counter-flow.
d. Counter-flow rather than parallel-flow.

A

c. Parallel-flow rather than counter-flow.

34
Q

(209) What should all low points be equipped with in a hydronic system?
a. Pump discharges.
b. Take offs.
c. Intakes.
d. Drains.

A

d. Drains.

35
Q

(210) How does an oversized duct affect airflow?
a. Ductwork will not affect airflow.
b. It increase the feet per minute.
c. It slows the air down.
d. It speeds the air up.

A

c. It slows the air down.

36
Q

(210) What effect will too much airflow have on noise?
a. The levels will be eliminated.
b. The levels will decrease.
c. The levels will increase.
d. It will sound softer.

A

c. The levels will increase.

37
Q

(210) What effect will a single-return on a plenum system have on installation cost?
a. A single return will be the same cost as any other system.
b. It will make the installation cost more expensive.
c. It will increase the installation cost by 65 percent.
d. It will make the installation cost cheaper.

A

d. It will make the installation cost cheaper.

38
Q

(210) Why does the plenum reduce in size?
a. To maintain static pressure.
b. To maintain air velocity.
c. To increase air velocity.
d. To decrease static pressure.

A

b. To maintain air velocity.

39
Q

(210) Why are perimeter loop systems placed around the perimeter of a building?
a. To prevent stratification.
b. To prevent static pressure loss.
c. Because that is where the greatest heat loss occurs.
d. Because that is where the least amount of heat loss occurs.

A

c. Because that is where the greatest heat loss occurs.

40
Q

(211) What do we treat air as in HVAC/R?
a. As five molecules.
b. As a compound.
c. As an individual gas.
d. As a single molecule.

A

c. As an individual gas.

41
Q

(211) Besides its molecules increasing speed, what else happens when air is heated?
a. It contracts and increases volume.
b. It expands and decreases volume.
c. It expands.
d. It contracts.

A

c. It expands.

42
Q

(211) You are going to calculate airflow volume, which formula would you use?
a. cfm = A x 2V.
b. V = A x cfm.
c. cfm = A/V.
d. cfm = A x V.

A

d. cfm = A x V.

43
Q

(211) What is relationship between air velocity and static pressure?
a. If static pressure drops, air velocity rises.
b. If static pressure rises, air velocity drops.
c. Static pressure is dependent of air velocity.
d. Static pressure is independent of air velocity.

A

d. Static pressure is independent of air velocity.

44
Q

(211) Where will you likely find a negative static pressure?
a. At the diffusers.
b. In the suction ductwork.
c. In the discharge ductwork.
d. While using a flowhood on a diffuser.

A

b. In the suction ductwork.

45
Q

(211) Where is gauge pressure at its maximum in an air system?
a. Before the fan intake.
b. At outside air intake.
c. At suction.
d. At discharge.

A

d. At discharge.

46
Q

(211) Where is gauge pressure normally at zero in an air system?
a. At the ends of duct runs.
b. At the fan intake.
c. At the fan discharge.
d. Zero pressure will never be achieved.

A

a. At the ends of duct runs.

47
Q

(212) What is relationship between static pressure and density?
a. They both rely on air velocity.
b. They are directly proportional.
c. They are indirectly proportional.
d. There is no relationship.

A

b. They are directly proportional.

48
Q

(212) To acquire the fan’s total pressure, you take the difference between
a. the static pressure at the fan outlet and total pressure at the fan inlet.
b. the total pressure at the fan inlet and static pressure at the fan inlet.
c. the total pressure at the fan outlet and total pressure at the fan inlet.
d. the total pressure at the fan outlet and static pressure at the fan inlet.

A

c. the total pressure at the fan outlet and total pressure at the fan inlet.

49
Q

(212) How would you obtain fan velocity pressure?
a. Take reading from discharge duct.
b. Take reading from intake duct.
c. Take the difference between the total fan outlet and fan inlet pressures.
d. Take the difference between the total and static discharge pressures.

A

d. Take the difference between the total and static discharge pressures.

50
Q

(212) Why must all pressure measurements be taken downstream of the fan discharge?
a. Static pressure is the strongest downstream.
b. Because the flow is more uniform downstream.
c. Because the flow is less uniform downstream.
d. The fan discharge is most uniform at discharge.

A

b. Because the flow is more uniform downstream.

51
Q

(212) How will brake horsepower be affected if revolutions per minute are increased and no other changes made?
a. It will decrease as energy consumption increases.
b. It will increase as energy consumption decreases.
c. It will decrease along with energy consumption.
d. It will increase along with energy consumption.

A

d. It will increase along with energy consumption.

52
Q

(212) What effect does cubic feet per minute (cfm) have on static pressure?
a. They have no relationship unless density is factored.
b. As cfm increases, static pressure decreases.
c. As cfm increases, static pressure increases.
d. As cfm decreases, static pressure increases.

A

c. As cfm increases, static pressure increases.

53
Q

(212) What effect does air density have on fan airflow?
a. Air density helps maintain constant airflow.
b. Air density increases airflow.
c. Air density reduces airflow.
d. No effect.

A

d. No effect.

54
Q

(213) When using a quarter-inch inclined gauge, where are the hose(s) attached on the gauge?
a. Connect the left side to negative.
b. Connect the right side to positive.
c. Right side to positive and left side to negative.
d. Left side to positive and right side to negative.

A

d. Left side to positive and right side to negative.

55
Q

(213) How is the pitot tube placed in the airstream?
a. Parallel and facing the airflow.
b. Parallel and facing away from airflow.
c. Perpendicular to the airflow.
d. Perpendicular and facing away.

A

a. Parallel and facing the airflow.

56
Q

(214) In air balancing, what do schematics allow the technician to plan?
a. Plan the sequence of balancing and determine where to take pitot traverses.
b. Plan the sequence of electrical components.
c. Focus on plumbing.
d. Focus on electricians.

A

a. Plan the sequence of balancing and determine where to take pitot traverses.

57
Q

(214) In air balancing, where do schematics provide the best service?
a. When blueprints are available.
b. When blueprints are easy to read.
c. When the system spans several floors.
d. When ductwork is very short and close.

A

c. When the system spans several floors.

58
Q

(214) What is the third step in air balancing?
a. Check the equipment.
b. Finalize the reports.
c. Prepare the reports.
d. Check out the building reports.

A

a. Check the equipment.

59
Q

(214) Which step in air balancing is “balance outlets and branch ducts”?
a. 1.
b. 2.
c. 3.
d. 4.

A

d. 4.

60
Q

(214) When are diffusers and grilles used in air balancing?
a. They are the only choice to balance a system.
b. For minor balancing or trim adjustments.
c. For major balancing adjustments.
d. Never.

A

b. For minor balancing or trim adjustments.

61
Q

(214) What is the first step in proportionate balancing?
a. Spot-check end outlets and outlets closest to fan.
b. Balance the last two branches.
c. Go to the fourth-to-last outlet.
d. Go to the third-to-last outlet.

A

a. Spot-check end outlets and outlets closest to fan.

62
Q

(214) What is the next step after a system has been proportionately balanced?
a. Recheck equipment readings.
b. Fill in the worksheets.
c. Prepare the reports.
d. Finalize reports.

A

a. Recheck equipment readings.

63
Q

(214) What is the final general air balancing step?
a. Prepare fan report.
b. Prepare the final outlet.
c. Finalize the test reports.
d. Fill in general information worksheet.

A

c. Finalize the test reports.

64
Q

(215) If balancing valves are used with orifice plates, why is the valve installed with sufficient distance up or down stream?
a. To avoid flow turbulence of the plate.
b. To utilize the turbulence of the plate.
c. Because lower pressures are required for proper readings.
d. Because higher pressures are required for proper readings.

A

a. To avoid flow turbulence of the plate.

65
Q

(216) “List the valves and terminals in the order they occur” falls under which step of preparing water-balance test reports?
a. Fill out the chiller test report.
b. Fill out the temperature water-balance report.
c. Fill out the flow or pressure-drop water-balance report.
d. Fill out the air-cooled condenser and compressor reports.

A

c. Fill out the flow or pressure-drop water-balance report.

66
Q

(216) “List the coil identification and room number in sequence” falls under which step of preparing water-balance test reports?
a. Fill out the chiller test report.
b. Fill out the temperature water-balance report.
c. Fill out the air-cooled condenser and compressor reports.
d. Fill out the flow or pressure-drop water-balance report.

A

b. Fill out the temperature water-balance report.

67
Q

(216) What is one step in balancing water terminals?
a. Read discharge line flow and compare with pressure measurements and curves.
b. Read and record initial flows without making adjustments.
c. Compare actual total head with pump catalog curve.
d. Read shutoff discharge and suction pressures.

A

b. Read and record initial flows without making adjustments.

68
Q

(217) Why is it important for you to know there is not a complete set of standards for symbols?
a. To discourage you from using the legend.
b. So you can try to memorize every symbol.
c. To create a sense of urgency when reading prints.
d. There’s room for error and to caution you not to make assumptions with blueprints.

A

d. There’s room for error and to caution you not to make assumptions with blueprints.

69
Q

(217) Which agency can a HVAC/R technician acquire blueprints?
a. Engineering flight or the contractor.
b. The blueprint and printing shop.
c. Plumbing shop.
d. Public health.

A

a. Engineering flight or the contractor.

70
Q

(217) Once all pipes, fittings and sizes are determined, what should you recheck?
a. The pipes.
b. Only the fans.
c. The electricians to determine power.
d. Each part of the system for completeness.

A

d. Each part of the system for completeness.

71
Q

(218) If a draftsman is creating detailed drawings, what type of views should be used?
a. Geographical location.
b. Year the device was made.
c. Sectional and detailed views.
d. The manufacturer.

A

c. Sectional and detailed views.

72
Q

(218) How should elevation views be shown when more than one view is used?
a. By a title.
b. Diffuser adjuster.
c. Diffuser modifications.
d. A flow hood will be combined with other tools to capture all of the air.

A

a. By a title.

HVAC CDC's (5 decks)

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