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WorksheetsIDA201 CH11 Thermostat Pressure Switch & Controls-Mr. Graham
Total questions: 15
Worksheet time: 8mins
What is the primary purpose of a control transformer in HVAC systems?
Increase voltage for compressors
Step down voltage for control circuits
Convert AC to DC
Provide backup power
What is the standard secondary voltage for most HVAC control transformers?
12 volts
24 volts
48 volts
120 volts
Which rating determines the load capacity of a transformer?
Watts
Voltamperes (VA)
Amperes only
Ohms
Which transformer would best replace a 120V primary, 24V secondary, 50 VA unit?
120/208/240V primary, 24V secondary, 40 VA
208/230V primary, 24V secondary, 50 VA
120/208/240V primary, 24V secondary, 60 VA
120V primary, 24V secondary, 20 VA
Line-voltage thermostats typically operate at:
12 volts
24 volts
120 or 208/240 volts
480 volts
Low-voltage thermostats are commonly used in:
Electric baseboard heaters
Residential heating and cooling systems
Large industrial chillers
DC-powered systems
What is the function of a heating anticipator in a mechanical thermostat?
Delay cooling cycle
Prevent overshooting heating setpoint
Increase temperature swing
Provide backup heat
Which terminal on a thermostat controls the indoor fan?
R
G
Y
W
What does the first stage of heating in a heat pump thermostat operate?
Gas furnace
Compressor
Electric resistance heaters
Emergency heat
Which statement about programmable thermostats is true?
They allow automatic temperature changes
They help save energy
They have override features
All of the above
Most communicating control systems use how many wires?
Two to four
Four to six
Six to eight
Eight to ten
Which is an advantage of Wi-Fi thermostats?
Remote control capability
Increased efficiency
System monitoring
All of the above
High-pressure switches are primarily used:
To control room temperature
As safety devices to prevent excessive discharge pressure
To regulate oil pressure
To start compressors
If a low-pressure switch has a cut-in of 45 psig and differential of 20 psig, what is the cut-out?
20 psig
25 psig
65 psig
55 psig
How is net oil pressure calculated by an oil safety switch?
Discharge pressure − suction pressure
Oil pump discharge pressure − suction pressure
Liquid line pressure − suction pressure
Oil pump discharge pressure − discharge pressure
