Question 1

A helix coil is used in some applications to sense temperature in a moving air stream.

Accepted Answer

A helix coil is sometimes used in thermocouples or thermometers to measure temperature in a rapidly moving fluid or gas stream. The coil is designed to bend or expand in response to changes in temperature, which can then be measured and recorded.

Question 2

A low pressure control has a "high event" and a "differential" setting. The technician wants the system to turn on at 28 psig and shut down at 2 psig. What would be the proper settings?
A) High event: 28 psig, differential: 2 psig.
B) High event: 2 psig, differential: 2 psig.
C) High event: 28 psig, differential: 26 psig.
D) High event: 2 psig, differential: 28 psig.

Accepted Answer

The proper settings would be a high event (cut-in) at 28 psig and a differential of 26 psig to ensure the system shuts down at 2 psig (28 psig - 26 psig = 2 psig).

Question 3

The difference between system overshoot and system lag is called ____.
A) room temperature
B) temperature rise
C) temperature swing
D) room swing

Accepted Answer

System overshoot and system lag are both related to temperature control systems. System overshoot occurs when the temperature exceeds the desired setpoint before eventually settling down to the setpoint. System lag occurs when the temperature takes some time to reach the desired setpoint. The difference between system overshoot and system lag is called temperature swing, which refers to the amount of deviation from the desired setpoint before the temperature stabilizes. Therefore, the correct answer is C) temperature swing. A) room temperature and D) room swing are unrelated to the concept of system overshoot and system lag. B) temperature rise is not the correct answer as it does not describe the difference between system overshoot and system lag.

Question 4

The heater in the thermostat control circuit in the cooling mode is active when the ____.
A) cooling contact is open
B) cooling contact is closed
C) fan switch is open
D) fan switch is closed

Accepted Answer

In the cooling mode, the heater in the thermostat control circuit is active when the cooling contact is open. This is because the heater is used to simulate a rise in temperature, causing the thermostat to activate the cooling system. When the cooling contact is open, it indicates that the cooling system is not currently active, and the heater can be used to trigger its activation.

Question 5

To prove that the combustion blower motor is operating before ignition, a ____ would be used.
A) toggle switch
B) pressure differential switch
C) push button switch
D) sail switch

Accepted Answer

A sail switch would be used to detect the air flow caused by the combustion blower motor to ensure that it is operating before ignition. The switch is activated by the air flow, which moves a small sail or paddle. If the sail or paddle does not move, then the switch will not close and the ignition sequence will not continue, ensuring that there is no risk of fuel being introduced into the combustion chamber without proper air flow.

Question 6

The purpose of a heat anticipator is to ____.
A) anticipate a sudden rise in temperature
B) keep the thermostat warm
C) reduce the temperature swing of a conditioned space
D) ensure that the system transformer does not overheat

Accepted Answer

The purpose of a heat anticipator is to reduce the temperature swing of a conditioned space by anticipating when the desired temperature will be reached and turning off the heating system before it overshoots the set point. This helps save energy and keeps the temperature more consistent. The other options (A, B, and D) are not accurate descriptions of the purpose of a heat anticipator.

Question 7

If the suction pressure of a system is 60 psig and the oil pump outlet is 85 psig, what is the net oil pressure?
A) 60 psig
B) 25 psig
C) 85 psig
D) 145 psig

Accepted Answer

The net oil pressure is the difference between the oil pump outlet pressure and the suction pressure. Therefore, the net oil pressure is 85 psig minus 60 psig, which equals 25 psig.

Question 8

To obtain an accurate reading of a fluid in a large pipe, a technician should ____.
A) strap a dial-type pocket thermometer to the pipe
B) use a digital thermometer in a glass of ice water
C) use a permanently mounted thermometer in a well
D) Any of the above will work fine.

Accepted Answer

Using a permanently mounted thermometer in a well will provide the most accurate reading of a fluid in a large pipe. Strapping a dial-type pocket thermometer to the pipe or using a digital thermometer in a glass of ice water may not provide accurate readings due to factors such as external temperature, insulation, or inconsistency of the fluid temperature throughout the pipe. Therefore, C is the best choice.

Question 9

Where would a water regulating valve that is controlling head pressure be installed?
A) Water circuit at inlet of condenser.
B) Discharge line at outlet of compressor.
C) Suction line.
D) Liquid line close to the condenser.

Accepted Answer

A water regulating valve controlling head pressure is typically installed in the water circuit at the inlet of the condenser to regulate the flow of water and maintain the desired pressure.

Question 10

Oil pressure safety controls measure the difference in pressure to establish ____.
A) the compressor is running
B) the oil pump is running
C) that negative oil pressure is present
D) that positive oil pressure is present

Accepted Answer

Oil pressure safety controls are designed to measure the difference in pressure to establish that positive oil pressure is present, indicating that the oil pump is running and providing lubrication to the engine components. This helps to prevent engine damage and failure.

Question 11

The cold anticipator is wired in ____ with the mercury bulb cooling contacts and is energized during the off cycle.
A) parallel
B) series
C) sequence
D) opposition

Accepted Answer

The cold anticipator is wired in parallel with the mercury bulb cooling contacts. This allows it to be energized during the off cycle, helping to manage the temperature more efficiently by anticipating the need for cooling before the space becomes too warm.

Question 12

To properly set the heat anticipator, the ____  must determine what the current flow is through the heating control circuit when the furnace is operating in a steady state condition .
A) manufacturer
B) homeowner
C) electrician
D) heating technician

Accepted Answer

The heating technician is the most qualified person to determine the current flow through the heating control circuit when the furnace is operating in a steady state condition, as they have the necessary knowledge and training to properly set the heat anticipator. The manufacturer may provide instructions, but the technician is responsible for carrying out the actual adjustment. The homeowner or electrician may not have the expertise to perform this task accurately.

Question 13

The cold anticipator starts the cooling system early to allow the air-conditioning system to get up to capacity when needed.

Accepted Answer

The cold anticipator is a control mechanism that starts the cooling system early, before the temperature rises, in order to give the air-conditioning system time to reach its full cooling capacity when needed.

Question 14

To control ice build-up on a heat pump outdoor coil in the heating cycle, a ____ is attached to a large diaphragm.
A) toggle switch
B) micro-switch
C) push button switch
D) sail switch

Accepted Answer

A micro-switch is used in conjunction with a large diaphragm to control ice build-up on a heat pump's outdoor coil during the heating cycle. This setup allows for precise control based on pressure changes, which can indicate ice formation.

Question 15

The heat anticipator in the thermostat control circuit in the heating mode is active when the ____.
A) heating contact is open
B) heating contact is closed
C) fan switch is open
D) fan switch is closed

Accepted Answer

The heat anticipator in the thermostat control circuit in the heating mode is active when the heating contact is closed. This is because the heat anticipator works by using a small resistor to mimic the heat load of the space being heated, and when the heating contact is closed, power flows through the resistor, heating it up and causing the thermostat to shut off the heating system slightly before the desired temperature is reached.

Question 16

The heat anticipator in a thermostat prevents the temperature in the conditioned space from rising above the thermostat setting.

Accepted Answer

The heat anticipator in a thermostat helps to prevent the temperature in the conditioned space from overshooting the set point by shutting off the heat before the space gets too warm, considering the residual heat that will be delivered while the heating system winds down.

Question 17

When a water regulating valve is used to control the head pressure of a water-cooled system, the valve's spring is acting against which pressure to modulate the water flow?
A) Head pressure of the system.
B) Water pressure.
C) Suction pressure.
D) Atmospheric pressure.

Accepted Answer

The purpose of a water regulating valve is to maintain a consistent head pressure in a water-cooled system. The valve's spring is designed to act against the head pressure of the system, which is the pressure of the water at the highest point of the system. By modulating the flow of water, the valve can maintain a consistent head pressure and ensure that the system operates efficiently. Therefore, the best choice is A) Head pressure of the system.

Question 18

Line voltage thermostats have heavier contacts and use which type of sensing element?
A) Bimetal.
B) Bellows.
C) Remote bulb.
D) All of the above.

Accepted Answer

Line voltage thermostats can use various types of sensing elements, including bimetal, bellows, and remote bulbs, to detect temperature changes. These elements enable the thermostat to control electrical circuits directly without the need for a transformer.

Question 19

What is meant by the term "detent"?
A) Slow motion of a contact to ensure good electrical contact.
B) Rapid making and breaking of a contact.
C) The compensation furnished by heaters in the thermostat.
D) The control of the blower in the air handler.

Accepted Answer

A detent refers to a mechanism that allows for the rapid making and breaking of a contact, often used in switches and locking devices to provide a firm engagement or disengagement.

Question 20

The advantage of using a thermistor-type thermometer over a mercury-filled thermometer for measuring refrigerant line temperature is that the thermistor-type does not have to be insulated.

Accepted Answer

Thermistor-type thermometers, like all temperature sensors, often require insulation when measuring refrigerant line temperatures to ensure accurate readings by minimizing the influence of ambient temperatures.

Quiz 14: Automatic Control Components and Applications

A helix coil is used in some applications to sense temperature in a moving air stream.

A low pressure control has a "high event" and a "differential" setting. The technician wants the system to turn on at 28 psig and shut down at 2 psig. What would be the proper settings?

The difference between system overshoot and system lag is called ____.

The heater in the thermostat control circuit in the cooling mode is active when the ____.

To prove that the combustion blower motor is operating before ignition, a ____ would be used.

The purpose of a heat anticipator is to ____.

If the suction pressure of a system is 60 psig and the oil pump outlet is 85 psig, what is the net oil pressure?

To obtain an accurate reading of a fluid in a large pipe, a technician should ____.

Where would a water regulating valve that is controlling head pressure be installed?

Oil pressure safety controls measure the difference in pressure to establish ____.

The cold anticipator is wired in ____ with the mercury bulb cooling contacts and is energized during the off cycle.

To properly set the heat anticipator, the ____ must determine what the current flow is through the heating control circuit when the furnace is operating in a steady state condition .

The cold anticipator starts the cooling system early to allow the air-conditioning system to get up to capacity when needed.

To control ice build-up on a heat pump outdoor coil in the heating cycle, a ____ is attached to a large diaphragm.

The heat anticipator in the thermostat control circuit in the heating mode is active when the ____.

The heat anticipator in a thermostat prevents the temperature in the conditioned space from rising above the thermostat setting.

When a water regulating valve is used to control the head pressure of a water-cooled system, the valve's spring is acting against which pressure to modulate the water flow?

Line voltage thermostats have heavier contacts and use which type of sensing element?

What is meant by the term "detent"?

The advantage of using a thermistor-type thermometer over a mercury-filled thermometer for measuring refrigerant line temperature is that the thermistor-type does not have to be insulated.