WorksheetsThermostat Quiz
Total questions: 93
Worksheet time: 52mins
In simplest terms, a thermostat is a sensing device that reacts to _____.
airflow
humidity
pressure
temperature
A thermostat that remembers set points and adapts system operation and cycles accordingly is a _____ thermostat.
learning
master
power-stealing
Wi-Fi
The type of HVAC system operation that regulates the increase or decrease of intensity and can result in significant energy usage reduction over time is _____ operation.
lockout
modulating
on-off
None of the above.
The longer a bimetal coil is, the _____.
less bending movement it can produce
longer it will stretch
more bending movement it can produce
shorter it will stretch
A switch used with a bimetal coil that consists of a pair of contacts in a glass tube that changes position based on magnets is a _____ switch.
mercury
reed
rod and tube
thermocouple
A switch used with a bimetal coil that consists of a glass tube containing wire contacts and a puddle of liquid metal and that changes position based on its physical position is a _____ switch.
mercury
reed
rod and tube
thermocouple
Electronic thermostats use a ______ to sense air temperature.
bimetal helix
sensing bulb and bellows
sensing bulb and diaphragm
thermistor
In the event of a mercury spill, ______.
call local hazardous material disposal agency
flush the mercury down the toilet
scoop up the mercury by hand
vacuum the mercury puddle
Identify each of the sensing elements shown.
The difference between a heating-only thermostat with two wires and a heating-only thermostat with three wires is the addition of a(n) ______.
automatic venting circuit
cut-out circuit
holding circuit
reversing circuit
For a heating thermostat, system overshoot occurs when temperature ______.
drops below the cut-in value
fails to reach the cut-in value
fails to reach the cut-out value
rises above the cut-out value
Temperature swing is the total difference between _______.
cut-in and cut-out temperatures
cut-in and the low temperature in a room
cut-out and the high temperature in a room
high and low temperatures in a room
For a heating thermostat, system lag occurs when temperature _______.
drops below the cut-in value
fails to reach the cut-in value
fails to reach the cut-out value
rises above the cut-out value
A heat anticipator's purpose is to switch _______.
on the heating system just before reaching the cut-in temperature
off the blower before turning off heat production
off the compressor before turning off the condenser fan
off the heating system just before reaching the cut-out temperature
A heat anticipator is always installed in _______.
a low-voltage dc circuit
parallel with the thermostat switch
series with the thermostat switch
a three-phase circuit
The anticipator affects basically small _______.
capacitors
diodes
resistors
transistor chips
A cooling anticipator's purpose is to switch _______.
on the cooling system just before reaching the cut-in temperature
off the blower before turning off the compressor
off the compressor before turning off the condenser fan
off the compressor just before reaching the cut-out temperature
A cooling anticipator is always installed in _______.
a low-voltage dc circuit
parallel with the thermostat switch
series with the thermostat switch
a three-phase circuit
The number of wires to connect to a combination thermostat depends primarily on _______.
how many wires are in the wire bundle at the base plate
technician preference
thermostat features and stages of operation
None of the above.
The primary purpose of a multistage thermostat is that it can control an HVAC system's _______.
capacity
energy usage
length of operation
wear and tear
If a forced-air electric heating system with a multistage thermostat was turned on and sensed that temperature was significantly below set point (more than 20°F or 11°C), it would _____.
energize all of the heating elements
energize only some of the heating elements
operate the burner at full capacity
run the compressor at full speed
If a multistage thermostat signaled for a cooling system's scroll compressor to run at less than full capacity, the scroll compressor would _____.
bypass a small amount of discharge vapor into the suction line
cycle on and off multiple times a minute
unload one or more cylinders
vent a small amount of high-side refrigerant to maintain lower head pressure
A multistage thermostat for a cooling system will have more than one _____ wiring terminal.
G
O/B
W
Y
A multistage thermostat for a heating system will have more than one _____ wiring terminal.
G
O/B
W
Y
In a single-family residence, line voltage is considered _____.
5 Vdc
24 Vac
120 Vac or 240 Vac
480 Vac
In a single-family residence, a line-voltage thermostat is primarily used to control _____.
electric baseboard heaters
an electric furnace
a gas furnace
a heat pump
A line-voltage thermostat _____.
can conduct higher current than other types of thermostats
must be installed in a locked box that is not accessible to the general public
must control devices through an isolation relay
requires the use of a step-down transformer
Un termostato de bajo voltaje típicamente se suministra con ____.
5 Vcc
24 Vcc
120 Vca o 240 Vca
480 Vca
Para controlar cargas de corriente más altas, un termostato de bajo voltaje normalmente usará ____.
un transformador de aislamiento
un interruptor de cuchilla
relés y contactores
un termistor
El valor VA de los transformadores reductores usados con termostatos se utiliza para determinar ____.
la corriente nominal del lado primario
el voltaje del lado primario
la corriente nominal del lado secundario
el voltaje del lado secundario
El cableado de termostato de bajo voltaje para longitudes de hasta 50' (15 m) normalmente debe ser al menos ____.
10 AWG
12 AWG
16 AWG
18 AWG
Los termostatos de milivoltios solo pueden usarse en sistemas de ____.
aire acondicionado
refrigeración comercial
calefacción
bomba de calor
Una ventaja que tienen los termostatos de milivoltios sobre otros termostatos es que no requieren ____.
fuente de energía externa
hardware
cableado
Todas las anteriores.
El elemento sensor utilizado en los termostatos de milivoltios es un(a) ____.
elemento higroscópico
bulbo sensor y fuelle
termistor
termocople
To operate, a millivolt thermostat depends on a(n) _____.
constant, steady draft
external power source
secondary heat exchanger
standing pilot light
The electrical load that a millivolt thermostat is used to actuate is a ____.
condensing unit contactor
reversing valve
sequencer
solenoid valve
The ability of modern thermostats to interface with mobile devices (smartphones, laptops, etc.) allows users to remotely control indoor environments.
True
False
A thermostat that draws a small amount of power from the low-voltage side of the HVAC system control to operate its electronics is a ____ thermostat.
multistage
power-stealing
wireless
zoning
Being able to schedule automatic operation using user set points is an advantage of a ____.
multistage
power-stealing
programmable
wireless
To prevent relay activation and other circuit board problems, power-stealing thermostats often require the addition of a bypass ____ to the circuit.
capacitor
manual switch
resistor
thermistor
What is the proper term for a common connection in thermostat installation?
Aux/E
C
DHD
G
Which term corresponds to the compressor contactor (stage 2) in thermostat wire terminal designations?
Aux/E
C
DHD
G
What designation is used for the cooling power in thermostat installation?
Y
W2
G
O/B
What is the correct term for the damper in thermostat wire terminal designations?
HMD
In or IDT
M1 or DMP
Rc
What designation corresponds to the dehumidifier in thermostat installation?
HMD
In or IDT
M1 or DMP
Rc
Which term is used for the fan relay (cooling only) in thermostat wire terminal designations?
Aux/E
C
G
M1 or DMP
What is the proper term for heating power in thermostat installation?
O/B
Rc
Rh
W
Which term corresponds to the heat pump auxiliary heat in thermostat wire terminal designations?
Aux/E
C
DHD
G
What designation is used for the heat relay (stage 1) in thermostat installation?
Y
W2
G
Rh
What is the correct term for the heat relay (stage 2) in thermostat wire terminal designations?
HMD
In or IDT
M1 or DMP
W2
What designation corresponds to the humidifier in thermostat installation?
HMD
In or IDT
M1 or DMP
Rc
Which term is used for the indoor temperature sensor in thermostat wire terminal designations?
Aux/E
C
G
Y
What is the proper term for the reversing valve in thermostat installation?
O/B
Rc
Rh
Y2
HVAC system settings are often set and managed using ______ on a circuit board or thermostat subbase.
DIP switches
wiring harnesses
wiring terminals
None of the above.
Free cooling is a method of cooling a building using a(n) ______.
air-side economizer
attic fan
earth-sheltered outer walls
evaporation of potable water
Free cooling is best done when outdoor air is ______.
cool and dry
cool and humid
hot and dry
hot and humid
For best results, free cooling should be used on a thermostat that has ______.
enthalpy control
power-stealing capabilities
solid-state switching
wireless connectivity
When free cooling is used on a forced-air system with mechanical air conditioning, a ______ thermostat is often used.
learning
millivolt
multistage
wireless
Identify the system component indicated by the letter 'A' in the following diagram.
Air handler
Barometric damper (open)
Inlet damper (open)
Return damper (closed)
Identify the system component indicated by the letter 'B' in the following diagram.
Air handler
Barometric damper (open)
Inlet damper (open)
Return damper (closed)
Identify the system component indicated by the letter 'C' in the following diagram.
Air handler
Barometric damper (open)
Inlet damper (open)
Return damper (closed)
Identify the system component indicated by the letter 'D' in the following diagram.
Air handler
Barometric damper (open)
Inlet damper (open)
Return damper (closed)
Identify the system component indicated by the letter 'E' in the following diagram.
Return plenum
Supply plenum
Air handler
Inlet damper (open)
Identify the system component indicated by the letter 'F' in the following diagram.
Return plenum
Supply plenum
Air handler
Inlet damper (open)
When installing a wireless thermostat, a good location for a temperature sensor would be ______.
anywhere on the ceiling
behind a door or in a corner
directly in front of a supply air register
on an inner wall about 5’ above the floor
When an HVAC system is set to operate in heating mode, a meter reading should indicate a(n) ______ across terminals R and Y.
closed circuit
high capacitance
low current
open circuit
When an HVAC system is operating in cooling mode, a meter reading should indicate a(n) ______ across terminals R and W.
closed circuit
high capacitance
low current
open circuit
When troubleshooting an HVAC system, if no voltage is measured across any of the pairs of thermostat wiring terminals, the problem is most likely with the wire connected to terminal ______.
G
R
W
Y
When troubleshooting a heating system that does not work, if source voltage can be measured in the thermostat, the problem is most likely with the wire connected to terminal ____.
G
R
W
Y
When measuring voltage across an open switch on a thermostat, expect to read ____.
0 V
source voltage
OL
None of the above.
If a heating system turns on once jumpers are placed across the proper wiring terminals in the thermostat, the problem is most likely the ____.
heating unit
thermostat
wires between thermostat and heating unit
None of the above.
When troubleshooting a cooling system that does not work, if source voltage can be measured in the thermostat, the problem is most likely with the wire connected to terminal ____.
G
R
W
Y
A multistage thermostat will only close its switch to terminal ____ once temperature drops below set point by more than 3°F (1.5°C).
W
W2
Y
Y2
A multistage thermostat will only close its switch to terminal ____ once temperature rises above set point by more than 3°F (1.5°C).
W
W2
Y
Y2
A step-down transformer used with a low-voltage thermostat should not have ____.
To compare a step-down transformer's secondary side VA rating with the VA of all the electrical loads in its circuit, a technician must add together each load’s ____.
current rating
voltage rating
resistance
All of the above.
In residential applications, live electrical measurements across terminals in an open line-voltage thermostat should be ____.
120 Vac or 240 Vac
5 Vdc
24 Vac
480 Vac
If line voltage is not measured across any of the terminals on the subbase of a line-voltage thermostat, then ____.
replace the thermostat with a new low-voltage thermostat
replace the thermostat with a new line-voltage thermostat
replace only the subbase
the problem is in the wiring
A zoned electric baseboard heating system provides zoning by controlling ____.
All of the above
dampers
electrical supply
valves and pumps
A zoned forced-air HVAC system provides zoning primarily by controlling ____.
dampers
electrical supply
valves and pumps
All of the above
A zoned hydronic system provides zoning by controlling ____.
valves and pumps
dampers
electrical supply
All of the above
If there is increased air pressure on the blower wheel of a forced-air zoned system, then the blower ____.
motor will draw more current than normal
control board will burn up
fan blades will bend out of shape
wheel mounting will loosen
When a forced-air zoned system that controls three zones receives a call to condition only one zone, sufficient airflow through the air handler is most easily, efficiently, and cost-effectively maintained by use of ____.
bypass dampers
multiple air handlers
venting conditioned air to outdoors
All of the above
Most rectangular dampers used to control airflow to a zone are ____ dampers.
multiple-blade
barometric
single-blade
temperature-operated
In order to close a normally open, two-wire zone damper, ____.
remove its return spring
switch off power to its motor
switch on power to its motor
turn off the blower to reduce static air pressure
An easy way to identify a power-open/power-closed damper is that it will have ____ connected to its motor.
one wire
two wires
three wires
two springs
A power-open/power-closed damper uses a(n) ____ to determine when the damper is in the closed position.
end switch
proximity switch
push button
set of normally open contacts along its sealing edge
A barometric damper's response to static air pressure can be accurately changed by adjusting ____.
the dial on its pressure controller
its settings on the zone control panel
its springs
its weights
In a zoned forced-air system with mechanical cooling, a freezestat opens with the purpose of turning off the ____.
air-side economizer
blower
compressor
zone control panel
If a small amount of frost begins to build up on an evaporator due to lower than normal airflow rates in a forced-air zoned system that is feeding air to only two of its three zones, the best solution from a zone control panel would be to ____.
automatically cycle off the compressor
open a motorized bypass damper and continue cooling operation
reverse compressor motor rotation to reverse refrigerant flow
turn on electric defrost elements and continue operation
If a solid ice buildup blocks an entire evaporator causing lower than normal airflow rates in a forced-air zoned system that is trying to feed air to only two of its three zones, the best solution from a zone control panel would be to ____.
automatically cycle off the compressor
open a motorized bypass damper and continue cooling operation
reverse compressor motor rotation to reverse refrigerant flow
turn on electric defrost elements and continue operation
Once all thermostats are satisfied in a forced-air zoned system, operation usually ends with all dampers _____.
fully open
at the halfway position
3/4 closed
fully closed
When measuring the electrical resistance of a damper motor in a forced-air zoned system, a good motor should have _____.
0 Ω
a small resistance value
several megohms of resistance
infinite resistance
