Sequence of operation of residential controls

Question 1

From the following description identify the component listed below. Is usually a single-phase, fractional hp motor.

Fan motor

Transformer

Fan control switch

Thermostat

Answer 1

Fan motor

Question 2

From the following description identify the component listed below. Is the operating controller for the appliance.

Fan motor

Transformer

Fan control switch

Thermostat

Answer 2

thermostat

Question 3

From the following description identify the component listed below. Supplies a millivolt signal to the automatic pilot valve section in the combination gas valve.

Transformer

Fan control switch

Thermocouple

High-limit switch

Answer 3

thermocouple

Question 4

what is the maximum VA output rating for a class 2 transformer

Answer 4

100 VA

Question 5

the temperature to which a thermostat is set is called the:

Answer 5

Set point

Question 6

What term describes a furnace that starts and stops frequently due to a lack of air movement through the heat exchanger?

Answer 6

High-limit cycling

Question 7

If the circulating air fan continues to run after the heat exchanger is cooled past 90° F, the air that is circulated to be quite cool in the building. Which Fan-limit control setting must be adjusted to correct the problem?

Answer 7

Fan-off switch

Question 8

While troubleshooting a thermostat a technician measures 24 V across the “R” and “W” contacts with the switch in the closed position. What is the most likely problem?

Answer 8

Heat anticipator is burned out

Question 9

A technician is troubleshooting a “No Heat” call on a 24 Volt control system. After the control circuit has been verified and power has been confirmed at the gas valve, how can the integrity of the gas valve be confirmed?

Answer 9

Using the continuity function of a multimeter, check the gas valve coil and replace the gas valve if this test shows an open circuit

Question 10

The 120 V heating system derives its name from its control circuit power rating 120 V.

T or F

Answer 10

True

Question 11

A transformer is typically required for a 120 V heating system.

T or F

Answer 11

True

Question 12

Thermostats utilized for commercial applications most likely have heat anticipators incorporated in their construction.

T or F

Answer 12

false

Question 13

With direct reference to the operating cycle of a commercial unit heater, what should be the next occurrence after the “Fan-on” setting has been reached?

Answer 13

The fan starts

Question 14

What adjustments to the fan-limit settings should be made by the technician when commissioning or performing routine maintenance on a commercial heating appliance?

Answer 14

As per manufacturer

Question 15

What is a common design incorporated into the gas valve of larger heating appliances?

Answer 15

Two stage (step) design

Question 16

What significant design change was incorporated in thermostats due to environmental concerns January 1, 2006?

Answer 16

Prohibited use of mercury filled bulb contacts

Question 17

Older mercury bulb thermostats can be disposed of in any trash receptacle.

T or F

Answer 17

false

Question 18

Spring-Activated, snap-action exposed contacts utilize what control principle to operate?

Answer 18

Bimetal

Question 19

For a cooling application, the thermostat contacts must __________when the room temperature falls.

Answer 19

open

Question 20

Name the terminal connections on basic heating and cooling
R
W
Y
G
C

Answer 20

R - Power
W - Heat (WARM)
Y - Cool (CHILLY)
G - Fan (FANG)
C - Common

Question 21

From the list below, which of the following would not be recommended when installing a thermostat?

Answer 21

Near other sources of heat or any position subjected to cold drafts, out of direct sunlight, away from any heat producing appliances

Question 22

It is recommended to use the built-in thermometer when calibrating a thermostat.

T or F

Answer 22

False

Question 23

The thermostat anticipator is wired in___________ with the thermostat contacts on a heating thermostat and in parallel to the contacts on a cooling thermostat.

Answer 23

Series

Question 24

The purpose of the anticipator is to compensate for the extra heat that is put into the room after burner shuts down.

T or F

Answer 24

True

Question 25

Any measurable temperature above or below the thermostat set point is called;

Answer 25

Offset

Question 26

The recommended way to calibrate a heat anticipator is;

Answer 26

Physically measure the control circuit amperage and set the anticipator to the measured amperage

Question 27

The anticipator may also be adjusted to change the cycle times of the appliance.

Answer 27

True

Question 28

Programmable thermostats; a) Provide multiple set-point values b) Allow for appliance operation during different day time periods c) Increase efficiency of the heating/cooling system d) All of the above

Answer 28

All of the above

Question 29

What term describes a combustion fan operating for a predetermined time prior to the ignition sequence?

Answer 29

Pre-purge

Question 30

With direct reference to the operational sequence of a mid-efficient furnace, what device must be last be activated before the ignition sequence can occur?

Answer 30

Air proving switch

Question 31

A mid-efficient furnace would fall under which category of the B-149.1 gas code?

Answer 31

class I

Question 32

The high-limit switch located in the heat exchange area of a mid-efficient furnace is normally of what design?

Answer 32

Snap-disc bimetal

Question 33

Where would a technician locate a VSS on a mid-efficient furnace?

Answer 33

Located near the vent outlet of the furnace

Question 34

A VSS or FRS would typically be;

Answer 34

Manual reset

Question 35

Spark and hot surface ignition systems would have trial for ignition time than an intermittent pilot ignition system.

Answer 35

A shorter

Question 36

Newer hot surface ignitors are constructed from .

Answer 36

Silicon nitride (NEWtride)

Question 37

Older mid-efficient furnaces would normally have blower speed/s. a) one b) more than one c) non-adjustable d) adjustable

Answer 37

More than one AND Adjustable

Question 38

Many of the new high-efficient furnaces utilize _________to improve operational efficiency through all firing rates and heating loads.

Answer 38

VAriable speed DC motors

Question 39

Which of the following would not be considered an input to an electronic control board?

Answer 39

Hot surface ignitor

Question 40

With reference to the operational sequence of a mid-efficient furnace, the delay-on timing sequence for the circulating air fan is adjustable. T of F

Answer 40

False

Question 41

With reference to the operational sequence of a mid-efficient furnace, if the combustion fan is operating but the hot surface ignitor fails to operate, what would be the first component for a technician to check?

Answer 41

Air switch

Question 42

How can a technician determine the proper circulating fan speed required for a mid-efficient furnace?

Answer 42

air temperature test

Question 43

If the measured heat rise in a furnace is higher than the manufacturers specification, how can a technician correct the problem?

Answer 43

Increase circulating air fan speed

Question 44

Changing circulating air fan speed on a mid-efficient furnace is done;

Answer 44

Manually

Question 45

Blower off delay adjustments are typically set by the manufacturer and are non-adjustable. T or F

Answer 45

false

Question 46

While verifying blower off delay setting on a mid-efficient furnace, a technician observes that the circulating air fan is de-energized with a discharge air plenum temperature of 120 °F. What can be done to correct this problem?

Answer 46

Increase the delay off time

Question 47

Some electronic control boards or ignition control centres come equipped with light-emitting diodes (LEDs). What is the primary purpose of these LEDs? A) Identify operational sequence B) Show fault conditions C) Assist with troubleshooting

Answer 47

Show fault conditions AND Assist with troubleshooting

Question 48

Manufacturers provide generic troubleshooting guides that apply to any appliance of the same design. T or F

Answer 48

False

Question 49

If a technician were to perform an upgrade to an existing heating system to a cooling, where would the evaporator coil be installed?

Answer 49

In the discharge (warm) air plenum

Question 50

What speed is typically used by default for the circulating air fan during cooling mode?

Answer 50

High

Question 51

What component of the control system must be checked (verified) for capacity when adding cooling components to an existing system?

Answer 51

Transformer VA | DO this when adding any component