110 Final review 1

Which of the following is an advantage of using a digital thermostat over a mechanical thermostat?

• More accurate temperature control

• Easier to read display

• Many have programmable functions

• All of the choices are correct

A high-pressure switch is usually used to ____________.

• Protect the compressor and system from excessively high discharge pressure

   

• Turn the compressor on when the discharge pressure rises to the correct level

   

• Protect the compressor from damage caused by low suction pressure

   

• Protect the condenser fan motor from damage caused by excessive discharge temperatures

An electrical device that responds to changes in temperature by opening and closing describes a ____________?

• Thermostat
• Pressure switch

• Rheostat

• Thermistor

To protect the equipment, a high-pressure switch used as a safety device must shut the equipment down by ____________.

• Modulating on rise of pressure

• Opening on fall of pressure

• Closing on rise of pressure

• Opening on rise of pressure

Transformers are rated by their ________________.

• Primary voltage

• Secondary voltage

• Voltamperes

• All of the choices are correct

What electrical device provides the low-voltage power source for the control circuits in heating and cooling equipment?

• Solenoid

• Inverter

• Transformer

• Voltage converter

What should the resistance be across the contacts of a pressure switch used as a safety device if the refrigeration systems pressures are in the normal range?

• Infinite ohms

• Three ohms

• Zero ohms

• 24 ohms

Which of the following choices is an advantage of using a system with communicating controls?

• Fault code and operational history logs for simplified troubleshooting

• Expanded options and capabilities specific to the system

• More precise and efficient operation of the system

• All of the choices are advantages of communicating control systems

All of the choices are advantages of communicating control systems except:

• Fault code and operational history logs for simplified troubleshooting

• Expanded options and capabilities specific to the system

• More precise and efficient operation of the system

• WiFi communication over the internet.

Which of the following choices matches the low-voltage heating and cooling thermostat letter designations with the correct function?

• W = cooling, Y = heating, G = Fan

• W = heating, Y = cooling, G = common from power supply

• W = voltage from transformer, Y = cooling, G = reversing valve

• W = heating, Y = cooling, G = Fan