Chapter 11 Electric Controls for Heating Systems Flashcards
1
Q
1.Three-way valves can be used in hydronic heating systems for \_\_\_\_\_ service. A. Mixing B. Pressure C. Volume D. Agitating E. Coagulating
A
A. Mixing
2
Q
2. The sensing element of the \_\_\_\_\_ is liquid filled and the switch is actuated by the expansion and contraction of the liquid when there is a temperature change of the controlled medium. A. Humidistat B. Pressurestat C. Bimetal thermostat D. Immersion thermostat or Aquastat E. Remote bulb thermostat
A
D. Immersion thermostat or Aquastat
3
Q
- When dealing with controls an actuator is a device:
A. Used to control the flow of air in a duct or through a wall louvre
B. Used to control the flow of fluid or gas such as water, air, or steam
C. That connects an actuator to a damper or control valve
D. Used to position dampers and control valves
E. Used to change AC voltage from one value to another
A
D. Used to position dampers and control valves
4
Q
- When dealing with controls a damper is a device:
A. Used to control the flow of fluid or gas such as water, air, or steam
B. Used to control the flow of air in a duct or through a wall louvre
C. That connects an actuator to a damper or control valve
D. Used to position dampers and control valves
E. Used to change AC voltage from one value to another
A
B. Used to control the flow of air in a duct or through a wall louvre
5
Q
5. In a typical electric control system the electric current is transmitted through a wire called the \_\_\_\_\_ to the burner. A. Neutral line B. Positive loop C. Negative loop D. Control link E. Connecting link
A
E. Connecting link
6
Q
- The sensing element of a remote bulb thermostat consists of a:
A. Diaphragm with sensing pressure on one side and a reference pressure on the other
B. Hygroscopic element
C. Bulb/capillary tube/bellows combination containing a volatile liquid
D. Bourdon tube
E. Strip made up of two thin layers of different metals which expand at widely different rates
A
C. Bulb/capillary tube/bellows combination containing a volatile liquid
7
Q
- When dealing with controls a controller is a device:
A. Which reacts to pressure, temperature, or humidity to provide two position, floating, or proportioning control of an actuator or relay
B. Used to change AC voltage from one value to another
C. That connects an actuator to a damper or control valve
D. Used to position dampers and control valves
E. Used to control the flow of fluid or gas such as water, air, or steam
A
A. Which reacts to pressure, temperature, or humidity to provide two position, floating, or proportioning control of an actuator or relay
8
Q
8. A room thermostat should be mounted on an inside about \_\_\_\_\_ above the floor and in the wall about path of natural air circulation when the heating system is off. A. 4.5 m (180 in) B. 1.5 m (60 in) C. 2.5 m (100 in) D. 3.5 m (140 in) E. 4.0 m (157 in)
A
B. 1.5 m (60 in)
9
Q
9. One of the most important controls in a heating system is the: A. Pressurestat B. Aquastat C. Operating control D. Thermostat E. Humidistat
A
D. Thermostat
10
Q
- When dealing with electrical controls line voltage refers to:
A. A term that refers to wiring or other electrical devices using 30 volts or less
B. A device used to change AC voltage from one value to another
C. A term that refers to the normal electric supply voltage
D. A device consisting of a solenoid coil, which operates load carrying contacts when the coil is energized
E. The electric switch configuration of a relay
A
C. A term that refers to the normal electric supply voltage
11
Q
- The electric modulating thermostat uses a _____ to produce a varying output signal.
A. Variable potentiometer B. Sensing bulb C. Bimetal strip D. Bourdon tube E. Bellows
A
A. Variable potentiometer
12
Q
12. Electrical contacts that complete electric circuits when a relay is de-energized are referred to as \_\_\_\_\_ contacts. A. Naturally open (NO) B. Normally open (NO) C. Normally closed (NC) D. Naturally Closed (NC) E. Not open (NO)
A
C. Normally closed (NC)
13
Q
13. A three-way valve is a: A. Gate-seated valve B. Ball-seated valve C. Triple-seated valve D. Single-seated valve E. Double-seated valve
A
E. Double-seated valve
14
Q
- Using electricity for control purposes has the following advantages except:
A. It is readily available.
B. The wiring is usually simple and easy to install.
C. A source of compressed air is required
D. The signals received from sensing elements can be used to produce more than one electro-mechanical output.
E. Single controller/actuator combinations are possible
A
C. A source of compressed air is required
15
Q
15. The duct thermostat is used to sense the air temperatures in: A. Rooms B. Coolers C. Freezers D. Boilers E. Ducts and plenums
A
E. Ducts and plenums