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Sheet Metal 4th Year > Troubleshooting > Flashcards

Troubleshooting Flashcards

1
Q

Household electrical outlets contain what type of current?

A

AC

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2
Q

A 24 volt hot surface intermittent pilot ignition system is known as a?

A

Smart valve

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3
Q

In an interrupted pilot ignition system, what state are the main burner and pilot in during standby?

A

They are both off

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4
Q

In which ignition system does the pilot stay on once the main burner is lit?

A

Intermittent

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5
Q

In a direct ignition system, what lights the burner in place of a pilot?

A

Spark

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6
Q

In a pilot ignition system, with an HSI, what lights the pilot and what lights the main burner?

A

The HSI lights the pilot and the pilot lights the main burner

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7
Q

Name the 2 parts of a dual rod pilot burner?

A

The short rod is the spark igniter and the second rod is the flame sensor

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8
Q

Where is a flame rod mounted?

A

So that it will be immersed in the main burner flame

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9
Q

What 2 voltages do HSI’s normally come in?

A

80V or 110V

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10
Q

What is the advantage of a valve train?

A

It allows you to replace components as needed instead of replacing the entire gas valve if there is a failure

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11
Q

What happens to voltage during flame rectification?

A

It changes from AC to DC

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12
Q

What is the ratio of the burner ground to the flame rod in flame rectification?

A

4 to 1

This is to ensure the current can be rectified from AC to DC

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13
Q

Can a continuous trial for ignition be allowed on propane appliances or direct ignition type systems?

A

No

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14
Q

How many times does the polarity change direction in a 60 Hz system?

A

120 times a second

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15
Q

What type of wiring diagram shows the colour of wires, the components and how they are connected to an appliance in standby mode?

A

Pictorial or connection diagram

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16
Q

What does a schematic or ladder diagram show?

A

How the appliance work for troubleshooting purposes

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17
Q

What 3 components make up a combination gas valve?

A

The solenoid valve, diaphragm valve and pressure regulator

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18
Q

What is the name given to the sequence of operations that take place before the gas valve opens?

A

Pre purge

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19
Q

What is the first step in the sequence of operation for a heating appliance with electronic ignition?

A

Call for heat at the thermostat

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20
Q

What are the typical voltage input and output on a transformer?

A

120 V input and 24 V output

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21
Q

What is used to measure gas pressure?

A

Manometer

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22
Q

When using a multimeter to check for continuity, is the appliance on or off?

A

It is off. The meter provides the power for this test.

23
Q

A multimeter will read volts in what type of circuit? And amps in?

A

Volts in parallel and amps in series

24
Q

1 psi = how many inches of wc?

A

27.7” wc

25
Q

What is used to measure the flow of electrons?

A

Amperage

26
Q

If you are using voltage, what are you measuring in regards to the electrons?

A

The force being applied to them

Electromotive force

27
Q

What is the formula to calculate watts?

A

Volts x amps = watts

28
Q

How does a transformer create energy?

A

Depending on the number of wraps, 120 wraps on the 120 V side or 24 wraps on the 24 V side, energy is created in an electromagnetic field

29
Q

Which safety control switch opens on temperature rise?

A

High limit switch

30
Q

What does the thermostat “switch” do on a temperature drop?

A

It closes on temperature fall

31
Q

What part of a furnace takes heat from products of combustion and moves it to a space that requires heat?

A

Heat exchanger

32
Q

What is the sequence of operation for a standard efficient furnace?

A 
Call for heat
Gas valve opens
Main burner lights
Blower turns on
Heat is satisfied 
Gas valve closes
Fan control is satisfied 
Blower turns off
Furnace is again in standby
33
Q 
What are the following thermostat terminals-
R
W
Y
G
C
A 
R-hot 24 power
W-heat
Y-cooling
G-fan
C-common
34
Q

What is the recommended manifold pressure for a natural gas furnace?

A

3.5” wc

35
Q

What gauge of wire is used for the 120 V side of the furnace?

The 24 V side?

A

120 side uses 14 gauge and the 24 side uses 18 gauge

36
Q

What is the sequence of operation for a high efficient furnace?

A 
Call for heat-R to W closes-24 V
The inducer motor starts-120 V
The pressure switch closes-24 V
The HSI energizes-120 V
Main valve energizes-24 V
Ignition takes place- Flame proves 0.8 secs
HSI deenergizes
Main blower energizes-120 V
Call for heat is satisfied -R-W opens
Main valve deenergizes
Inducer motor runs a post purge and then shuts down -5 second delay
Blower fan turns off-90-210 second delay
Furnace is now in standby
37
Q

What 2 factors should be checked when calibrating thermostats?

A

Operating temperature and operating differential

38
Q

What control piece of equipment can be used to reset a lock out on a furnace?

A

Thermostat

39
Q

Name a component that is an automatic or remote control device that uses one or more initiating devices to operate or control another device?

A

A relay

40
Q

What component is used to either increase the running efficiency of the motor or give it an initial boost in torque at start up?

A

Capacitor

41
Q

What is the recommended way to discharge a capacitor?

A

A 10 watt resistor

42
Q

Is a flame rollout switch on the furnace a manual or automatic reset?

A

Manual

43
Q

What is the purpose of the inducer motor?

A

To assist the flue gases to rise up through the vent

44
Q

How is a pressure switch connected and wired?

A

It is connected to the inducer motor assembly and wired in series with the gas valve

45
Q

What does a manometer measure?

A

Pressure

46
Q

What type of pressure is found on the supply side and what type of pressure is found on the return side of the HVAC system?

A

Supply side is positive and return side is negative

47
Q

What type of metre combines voltmeter, ohmmeter and amp meter?

A

Multimeter

48
Q

Name four types of efficiencies?

A

Combustion efficiency
Steady state efficiency
Annual fuel utilization efficiency
Thermal efficiency

49
Q

What is the stack temperature or flu exhaust temperature of a standard efficient furnace? A mid efficient furnace? A high efficient furnace?

A

Standard-500° F
Mid-350° F
High-110° F

50
Q

What does low oxygen indicate when troubleshooting a furnace in regards to combustion?

A

There is insufficient combustion air

51
Q

What does high oxygen levels indicate when troubleshooting in regards to combustion?

A

Too much combustion air

52
Q

Which dial is used for the purpose of clocking the meter?

A

The proving dial

53
Q

What can be done if the temperature rise on the furnace during initial start up is too low? Or if the temperature rise is too high?

A

If it is too low you must decrease the fan speed and if it is too high you must increase the fan speed

54
Q

What are two ways to adjust the fan on and the fan off setting on a furnace?

A

Switching positions of dip switches or changing locations of a jumper

Sheet Metal 4th Year (5 decks)

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