HVAC Controls Trivia Questions! Quiz

27 Questions | By Hostileholly | Updated: Mar 21, 2022 | Attempts: 304

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HVAC Controls Trivia Questions! Quiz - Quiz

HVAC Controls Final Quiz

Questions and Answers

1.

The control result is not monitored for which system? (i.e. The output variable xa of the controlled system has no backward effect on the controlling equipment)
- A.
  
  Open Loop
- B.
  
  Closed Loop
2.

A humidification sequence would use what type of controller?
- A.
  
  Direct acting
- B.
  
  Reverse Acting
3.

HVAC systems are almost always:
- A.
  
  Non self-regulating (astatic or integral system, I-systems)
- B.
  
  Self-regulating (static or proportional systems, P-systems)
4.

The Transfer Coefficient of the Controlled System is represented by
- A.
  
  Tn
- B.
  
  Tv
- C.
  
  Ks
- D.
  
  Kd
- E.
  
  Xh
5.

If the control range Xh is too large, then...
- A.
  
  The setpoint can't be achieved if the maximum disturbance variable occurs
- B.
  
  The control loop tends to oscillate
6.

In PT1, the 1 refers to:
- A.
  
  One storage element
- B.
  
  One control system
- C.
  
  One slave controller
7.

The controllability of a system ___________ with an increasing number of storage elements.
- A.
  
  Increases
- B.
  
  Decreases
- C.
  
  Doesn't change
8.

Which of the following is not a way to describe the dynamic response of a controlled system?
- A.
  
  Description via step response
- B.
  
  Description by the Ziegler-Nichols method
- C.
  
  Description by the control variable response
- D.
  
  Description via the frequency response (harmonic response)
9.

Information on how the controlled system reacts to a sudden increase in heat gains would be best provided by:
- A.
  
  Manipulated variable step response
- B.
  
  Disturbance variable step response
10.

The "correcting span" is:
- A.
  
  Xp
- B.
  
  Xh
- C.
  
  Yh
- D.
  
  Tv
11.

The main storage element in an electrically heated hot water tank is the:
- A.
  
  Electric resistance element
- B.
  
  Water
- C.
  
  Agitator
- D.
  
  Thermometer
- E.
  
  Tank Insulation
12.

Is dead time the same as travel time?
- A.
  
  Yes
- B.
  
  No
13.

If there are a lot of storage elements in the system, the step response:
- A.
  
  Has a steeper slope
- B.
  
  Has a gentler slope
14.

Tu, Tg, and Ts are (in order)
- A.
  
  Balancing Time, Delay Time, Time Constant
- B.
  
  Time Constant, Balancing Time, Delay Time
- C.
  
  Delay Time, Time Constant, Balancing Time
- D.
  
  Delay Time, Balancing Time, Time Constant
15.

The degree of difficulty S (Tu/Tg) represents:
- A.
  
  The control range of a control system
- B.
  
  The controllability of a controlled system
- C.
  
  The reaction time of a controlled system
16.

A difficult-to-control system has a degree of difficulty (S) of:
- A.
  
  S
- B.
  
  S=0.1...0.3
- C.
  
  S>0.3
17.

Controlled systems in the ventilation field tend to have ______degrees of difficulty and _________ balancing times when compared to the heating field.
- A.
  
  Higher, longer
- B.
  
  Higher, shorter
- C.
  
  Lower, longer
- D.
  
  Lower, shorter
18.

The oscillation test (Ziegler-Nichols method) is performed in what environment?
- A.
  
  Closed Loop
- B.
  
  Open Loop
19.

________ controllers are mainly used for temperature, pressure, or level control.
- A.
  
  Powered controllers
- B.
  
  Self-actuated controllers
20.

A direct-acting controller only activates its output if e is
- A.
  
  Less than 0
- B.
  
  Greater than 0
21.

Which controller type can position its output variable at two or more pre-defined values within the entire correcting span Yh?
- A.
  
  Two-position
- B.
  
  Modulating
- C.
  
  Non-modulating
- D.
  
  Quasi-modulating
22.

The smaller the proportional band Xp that is selected, the __________________ the offset will be, but the ______ the tendency of the control loop to oscillate.
- A.
  
  Larger, smaller
- B.
  
  Smaller, greater
23.

True or false: the P-controller is load-independent and the I-controller is load-dependent.
- A.
  
  True
- B.
  
  False
24.

A two-position controller would be a good choice for all but which of the following applications?
- A.
  
  As a hygrostat to switch the humidifier of a room humidity control system
- B.
  
  As a pressostat to switch the compressor of a compressed air station
- C.
  
  As a flow temperature low-limit controller in a floor heating system
- D.
  
  As a temperature controller for a domestic hot water heater
- E.
  
  As a frost protection thermostat in a ventilation system
25.

A generally applied rule of thumb recommends that the loop gain Vo should be set to __________ of the critical loop gain.
- A.
  
  One-fourth
- B.
  
  Half
- C.
  
  Three-fourths