Name:
Class:
Date:
Copyright Cengage Learning. Powered by Cognero.
Page 1
Indicate whether the statement is true or false.
1. PEX tubing has lower temperature-pressure ratings than HDPE tubing.
a.
True
b.
False
2. Gate valves are designed specifically for flow regulation.
a.
True
b.
False
3. A diaphragm-type expansion tank works by allowing air to be compressed.
a.
True
b.
False
4. With conventional boilers, sustained flue gas condensation is an undesirable condition.
a.
True
b.
False
5. The degree of hydraulic separation between two operating circulators depends on the head loss in the common piping.
a.
True
b.
False
Indicate the answer choice that best completes the statement or answers the question.
6. What conditions describe the operating point of a hydraulic circuit?
a.
the condition just below hydraulic equilibrium on the pump curve
b.
the rate at which the circulator adds head equals the piping head loss rate
c.
where the inlet and outlet water temperatures are identical
d.
the rate at which the circulator adds head is slightly greater than the piping head loss rate
7. What happens with air as heated water is cooled?
a.
Air molecules rise out of the solution.
b.
Air molecules are absorbed back into the solution.
c.
The number of air molecules in the solution remains the same.
d.
The air molecules change phase.
8. What cools the motor of a wet-rotor circulator?
a.
oil
b.
external water source
c.
cooling fan
d.
the system’s fluid
9. How do brazed-plate heat exchangers work?
a.
Two fluids flowing in the same direction exchange heat as they pass by each other.
b.
Heat is transferred by conduction through the copper, brazed areas.
Name:
Class:
Date:
Copyright Cengage Learning. Powered by Cognero.
Page 2
c.
Heat is transferred by mixing two fluids.
d.
Heat is transferred in the small spaces between formed plates.
10. Which is the standard size for copper water tubes used in hydronic heating systems?
a.
type M
b.
type K
c.
type L
d.
type D
11. In a condensing boiler, where does the condensation occur?
a.
in the combustion chamber
b.
in the primary heat exchanger
c.
in the secondary heat exchanger
d.
at the water inlet
12. What is the best description of the operation of a microbubble air separator?
a.
It creates areas of reduced pressure using a coalescing media.
b.
It creates areas of increased pressure using a coalescing media.
c.
It uses a float-type air vent to allow air to escape naturally.
d.
It consolidates small bubbles into large ones by narrowing the length of the pipe.
13. Which type of valve routs flow through different parts of a system depending on its current operating mode?
a.
3-way mixing valve
b.
3-way diverting valve
c.
port valve
d.
backflow preventer
14. What is the primary function of a hydronic mixing valve?
a.
to raise water temperature coming from the heat source
b.
to lower water temperature coming from the heat source
c.
to mix two system fluids
d.
to regulate flow rates between different zones of a system
15. What is the first step in selecting a circulator for a fluid-filled circuit?
a.
Determine the desired system flow rate based on thermal and flow requirements of the heat emitters.
b.
Use the system loss curve to determine the head loss of the system.
c.
Research the coefficient of performance of the pump.
d.
Select a circulator that delivers ten percent more head than required.
16. How does an operating circulator affect the head energy as fluid passes through?
a.
It increases the head energy of the fluid.
b.
It decreases the head energy of the fluid.
c.
It transfers the head energy from the fluid to the heat emitter.
d.
The head energy of the fluid does not change.
Name:
Class:
Date:
Copyright Cengage Learning. Powered by Cognero.
Page 3
17. Ideally, when should air be eliminated in a closed-loop, fluid-filled circuit?
a.
before startup
b.
shortly after startup
c.
at regular intervals during the life of the system
d.
never
18. What is the primary function of a feedwater valve?
a.
to lower water pressure as it enters the system from a domestic water distribution pipe
b.
to increase water pressure as it enters the system from a domestic water distribution pipe
c.
to allow air to exit the system
d.
to increase water temperature as it enters the system
19. What variable is typically plotted on the x-axis (horizontal axis) of a circulator pump curve?
a.
pump curve family
b.
pressure
c.
flow rate
d.
temperature
20. What is the ideal approach temperature difference in a brazed-plate heat exchanger?
a.
zero
b.
ten degrees
c.
twenty degrees
d.
the maximum that can be achieved
Name:
Class:
Date:
Copyright Cengage Learning. Powered by Cognero.
Page 4
1. False
2. False
3. True
4. True
5. True
6. b
7. b
8. d
9. d
10. a
11. c
12. a
13. b
14. b
15. a
16. a
17. b
18. a
19. c
20. a