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Worksheets08. ACR-105 UNIT 14 END OF UNIT TEST
Total questions: 34
Worksheet time: 32mins
The purpose of a heat anticipator is to ____.
anticipate a sudden rise in temperature
keep the thermostat warm
reduce the temperature swing of a conditioned space
ensure that the system transformer does not overheat
The difference between system overshoot and system lag is called ____.
room temperature
temperature rise
temperature swing
room swing
What is meant by the term "detent"?
Slow motion of a contact to ensure good electrical contact.
Rapid making and breaking of a contact.
The compensation furnished by heaters in the thermostat.
The control of the blower in the air handler.
The heat anticipator in the thermostat control circuit in the heating mode is active when the ____.
heating contact is open
heating contact is closed
fan switch is open
fan switch is closed
The heater in the thermostat control circuit in the cooling mode is active when the ____.
cooling contact is open
cooling contact is closed
fan switch is open
fan switch is closed
The cold anticipator is wired in ____ with the mercury bulb cooling contacts and is energized during the off cycle.
parallel
series
sequence
opposition
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.
manufacturer
homeowner
electrician
heating technician
Line voltage thermostats have heavier contacts and use which type of sensing element?
Bimetal.
Bellows.
To obtain an accurate reading of a fluid in a large pipe, a technician should ____.
strap a dial-type pocket thermometer to the pipe
use a digital thermometer in a glass of ice water
use a permanently mounted thermometer in a well
Any of the above will work fine.
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?
High event: 28 psig, differential: 2 psig.
High event: 2 psig, differential: 2 psig.
High event: 28 psig, differential: 26 psig.
High event: 2 psig, differential: 28 psig.
If the suction pressure of a system is 60 psig and the oil pump outlet is 85 psig, what is the net oil pressure?
60 psig
25 psig
85 psig
145 psig
Oil pressure safety controls measure the difference in pressure to establish ____.
the compressor is running
the oil pump is running
that negative oil pressure is present
that positive oil pressure is present
To prove that the combustion blower motor is operating before ignition, a ____ would be used.
toggle switch
pressure differential switch
push button switch
sail switch
To control ice build-up on a heat pump outdoor coil in the heating cycle, a ____ is attached to a large diaphragm.
toggle switch
micro-switch
push button switch
sail switch
Where would a water regulating valve that is controlling head pressure be installed?
Water circuit at inlet of condenser.
Water circuit at outlet of condenser.
Refrigerant circuit at inlet of condenser.
Refrigerant circuit at outlet of condenser.
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?
Head pressure of the system.
Water pressure.
Suction pressure.
Atmospheric pressure.
The heat anticipator in a thermostat prevents the temperature in the conditioned space from rising above the thermostat setting.
True
False
The cold anticipator starts the cooling system early to allow the air-conditioning system to get up to capacity when needed.
True
False
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.
True
False
A helix coil is used in some applications to sense temperature in a moving air stream.
True
False
A dual pressure control is actually a low pressure control and a high pressure control connected in parallel with each other.
True
False
Many natural gas fired heating units operate at a manifold pressure of 3.5 in. WC.
True
False
The statement is true.
True
False
The term used to describe when the temperature of a heated room falls below the thermostat's set point is called .
The term used to describe when the temperature of a heated room rises above the thermostat's set point is .
The heater that functions in a thermostat in the heating mode is called the .
The heater that functions in a thermostat in the cooling mode is called the .
High pressure control contacts are normally type.
List four reasons why low voltage controls are usually found on residential air conditioning systems.
Safety, cost-effectiveness, ease of installation, and energy efficiency
High power output, durability, complex installation, and high cost
Increased noise, higher energy consumption, larger size, and more maintenance
Limited functionality, higher voltage requirements, less reliability, and increased risk
What is the most accurate way to measure the current through the heat anticipator?
measure the current through the heating anticipator is with an AC ammeter measuring current between the R and W terminals of the thermostat’s subbase.
Using a clamp meter around the anticipator
Using a voltmeter across the anticipator
Using an ohmmeter across the anticipator
Where is the thermistor motor overload device usually positioned?
embedded in the motor windings.
In the control panel
On the motor shaft
Inside the motor casing
Why is the thermistor type sensor normally embedded in the motor windings?
The close contact with the windings gives fast, accurate response.
To reduce the size of the motor
To increase the efficiency of the motor
To decrease the cost of the motor
What type of control would be used to cycle compressors on and off in response to evaporator pressures that indirectly control box temperatures?
Thermostatic Expansion Valve
A low-pressure control would be used.
Humidity Control
Temperature Control
What device may be used to ensure that air is flowing through a duct before an electric strip heater is energized?
Thermostat
Pressure switch
A sail switch may be used.
Humidity sensor
