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2nd year sheet metal > Furnace commissioning > Flashcards

Furnace commissioning Flashcards

1
Q

What type of pump would be used to lift water in below grade submersed situations?

A

Sump pump

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2
Q

What is the purpose of a foot valve?

A

Prevent water from leaving the suction line

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3
Q

How is a sump or sewage pump controlled?

A

Float switch

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4
Q

What are materials that readily give up their electrons called?

A

Conductors

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5
Q

What must happen when measuring resistance of a device in a circuit?

A

Disconnect the device being checked and place the test leads in series with the device

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6
Q

Which type of pilot burner draws primary air into the burner at the point of combustion eliminating the chance of dust to be present?

A

Post aerated pilot

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7
Q

What can happen if a pilot burner is not adjusted properly and metal is impinging in the pilot flame?

A

The flame will cool and cause incomplete combustion

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8
Q

Describe a heating thermostat.

A

Temperature sensing switch that closes on temperature fall

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9
Q

What happens in the furnace when the high limit switch opens?

A

Gas flow is turned off and the blower is energized

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10
Q

What is the purpose of a draft hood in a gas appliance?

A

Provide a break in the stack action and prevent the products of combustion from down drafting and entering the heat exchanger

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11
Q

What device can control one or more initiating devices in a circuit?

A

Relay

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12
Q

What type of capacitor would be used with a single phase motor?

A

Run capacitor

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13
Q

What unit of measure is used for testing capacitors?

A

Farads

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14
Q

When referencing flow of the products of combustion, where in a gas furnace is the inducer motor located?

A

Downstream of the burner and heat exchanger

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15
Q

Which safety limit switch automatically resets?

A

Main high limit

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16
Q

What is the recommended spark gap for the pilot ignition spark?

A

1/8”

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17
Q

What is the purpose of a dirt pocket when installed at the appliance gas line drop?

A

Collect filings and foreign materials

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18
Q

What gas line material is used above ground, can be cut to any length, uses manufactured specialty fittings and is flexible for fewer connections?

A

CSST-corrugated stainless steel tubing

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19
Q

How far must the vent of a regulator be from a moisture exhaust vent?

A

3’

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20
Q

What needs to be done to a gas appliance when installing at high altitudes as per specifications?

A

Derate by 10% for altitudes between 2000’ and 4500’. Over 4500’, the input rating shall be reduced at the rate of 4% for each additional 1000’. (Decrease BTUH)

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21
Q

What is required for the safe operation of a water boiler if the system drains?

A

Low level cut off

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22
Q

What are 2 main principles in flame rod detection?

A

Flame rectification and flame conductivity

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23
Q

What type of ignition system, on a call for heat, lights the pilot, proves the pilot is lit, lights the main burner, proves the main burner and then shuts off the pilot as it is no longer needed?

A

Interrupted pilot ignition

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24
Q

What type of system uses a spark to light the main burner?

A

Direct spark ignition

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25
Q

What is required for the flame proving circuit to become rectified?

A

The larger ratio between the ground and flame rod allowing current to flow more in one direction

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26
Q

What function does a CPU perform in a gas furnace?

A

Executes a series of stored instructions

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27
Q

What can be used to adjust fan off timers in a gas furnace?

A

Dip switch

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28
Q

What are the more reliable hot surface igniters made of- silicone carbide or silicone nitride?

A

Silicone nitride

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29
Q

Name 3 approved gas leak detection methods?

A

Soapy water solution, test dial, electronic leak detector

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30
Q

What type of venting must be used when installing a condensing gas appliance?

A

BH vent

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31
Q

If the temperature rise in a furnace is too high, what must be done according to the rating plate?

A

Increase fan speed

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32
Q

What type of pilot burner uses primary air and secondary air for combustion and burn continuously?

A

Aerated standing pilot burner

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33
Q

What needs to be done to the pilot burner when converting fuels from natural gas to propane?

A

Change the insert orifice to a smaller sized orifice

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34
Q

What does a heat anticipator accomplish in a mechanical thermostat?

A

Lessen room temperature swings

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35
Q

Which high limit safety device comes with a manual reset button?

A

Flame roll out

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36
Q

What 3 components make up the atom?

A

Electrons, neutrons and protons

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37
Q

What are the electrons in the outermost orbit of an atom called?

A

Valence

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38
Q

Materials that easily give up electrons are known as?

A

Conductors

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39
Q

Current can be described as the flow of ____________ which is measured in ____________?

A

Electrons, amperes

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40
Q

What is the unit of measure for the number of cycles per second, when referencing alternating current?

A

Hertz

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41
Q

Name 3 examples of electromotive force that can produce voltage?

A

Magnetic, heat and friction

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42
Q

What 3 things are required for electricity to flow?

A

Path, source and load

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43
Q

In this electrical circuit, what component would be considered the load-
battery
light bulb
switch or
transformer?

A

Light bulb

44
Q

What is a continuity test used to determine?

A

If an electrical circuit is complete

45
Q

What can be used to check an electrical circuit for live voltage?

A

Voltage pen or test light

46
Q

What type of meter should never be connected to an energized circuit?

A

Ohmmeter

47
Q

When comparing schedule 40 and schedule 80 pipe, what happens to the inside diameter as the wall thickness increases?

A

Inside diameter decreases

48
Q

What is the included angle of a NPT?

A

60 degrees (National Pipe Thread)

49
Q

When threading pipe, what is the cutting fluid used for?

A

To help keep the pipe and threading dies cool

50
Q

When the pipe has been cut to the correct length, what must be done before threading begins?

A

Clean die threads, ream pipe and oil

51
Q

What type of piping cannot be used in above ground installations?

A

Polyethylene

52
Q

What is the definition of thread engagement?

A

The amount of pipe that is added to a face to face measurement

53
Q

Why is teflon tape used on an iron thread?

A

Lubricate the joint

54
Q

What is type M copper used for?

A

Potable water

55
Q

In HVAC, where can aluminum tubing be used?

A

Pilot gas from gas valve to pilot burner

56
Q

What must be done if a gas furnace heat exchanger is deemed defective?

A

Replace with same approved heat exchanger

57
Q

What must be installed in conjunction with a regulator?

A

Shut off valve

58
Q

What would a plugged regulator vent cause?

A

An increase in outlet pressure

59
Q

What is it called when the flow of gas has stopped completely by the regulator?

A

Lock up

60
Q

What is the minimum distance between a regulator vent termination and mechanical air intake?

A

10’

61
Q

What is the area of the common manifold when venting 2 or more regulators together, without internal relief?

A

2 x the total area of the connected bleed vents

62
Q

What is the maximum pressure setting of the 1st stage regulator in a residential propane installation?

A

No more than 10 psig

63
Q

What are the 3 main elements of a regulator?

A

Orifice (the restricting element), diaphragm (the measuring element) and spring (the loading element)

64
Q

What is an orifice designed to do?

A

Control rate of flow of gas to the burner

65
Q

What is the proper way to verify the actual size of an orifice?

A

Using the shank of the orifice drill

66
Q

What is a leak limiting device used for?

A

To limit the amount of gas escaping if the diaphragm ruptures. (1cu.ft/hr for propane and 2.5cu.ft/hr for natural gas

67
Q

When is a leak limiting device used?

A

On 2psig or lower pressure systems in a well ventilated space only

68
Q

What 2 devices on a regulator, are used to control excess pressure?

A

Internal and external relief valves

69
Q

How is a regulator freeze up identified?

A

By a lack of gas to the burners (slow or sluggish operation)

70
Q

What does a plugged regulator vent cause?

A

Excessively high outlet pressures

71
Q

What position does a gas valve fail in?

A

Closed position

72
Q

Name 4 types of pressure regulators?

A

Service, system, appliance and servo

73
Q

What closes the regulator valve stem?

A

Gas pressure

74
Q

How do you change rotation in a belt drive motor?

A

Reverse the wires under the cover plate

75
Q

How do you test a low water cut off control on a boiler?

A

Drain the boiler

76
Q

What type of valve is used on a propane tank for liquid withdrawal?

A

Excess flow valve

77
Q

How close to the side of a building can an RTU be located?

A

6’

78
Q

How far from a masonry wall does a 7500L propane tank have to be located?

A

10’

79
Q

What needs to be checked on a transformer if it has been replaced multiple times?

A

VA rating

80
Q

How many support legs minimum are needed on a horizontal propane tank?

A

2

81
Q

What type of pipe is not allowed for liquid propane and cannot be used in above ground installations?

A

Polyethylene

82
Q

What are the LEL and UEL for propane?

A

2.3% to 9.5%

83
Q

What are the LEL and UEL for natural gas?

A

5% to 15%

84
Q

What is the piping between the well head and the processor called?

A

Production lines

85
Q

What is the piping between the city gate and the building called?

A

Distribution lines

86
Q

What type of venting is used on a high efficient oil fired furnace?

A

L vent

87
Q

How must a steam boiler be wired for an operator control and a safety control-
series and series
parallel and series
parallel

A

Series and series

88
Q

What class category is a 24 volt transformer?

A

Class 2

89
Q

What common voltage, used in furnaces, is found on the secondary side of a transformer?

A

24V

90
Q

When testing resistance, how must the meter be hooked up and is the circuit energized or deenergized?

A

The circuit is deenergized and the meter leads are hooked up in series

91
Q

On a gas fired residential furnace, where would the main high limit switch be located?

A

Next to the heat exchanger

92
Q

What is determined by clocking the gas meter?

A

BTUH input of the appliance

93
Q

Calculate the BTUH for a natural gas fired furnace that took 45 seconds to complete 1 revolution on a 1 cubic foot dial?

A

1/45=0.0222 x 3600=80
This gives you the cubic feet of gas, now you need to multiply that by the calorific value of the fuel to get the BTUH.
80 x 1000= 80,000 BTUH

94
Q

What must be done to the fan speed if the temperature rise in a furnace is too high according to the rating plate?

A

Fan speed should be increased

95
Q

How do you test the high limit in a gas fired residential furnace?

A

Disconnect the heating fan speed wire from the terminal and do a call for heat.

96
Q

What happens to the pilot in an intermittent and interrupted ignition system?

A

Intermittent-pilot stays on after main burner is lit
Interrupted-pilot turns off after main burner is lit

97
Q

What is the included angle of a NPT (National Pipe Thread)?

A

60 degrees

98
Q

What is cutting oil used for in threading pipe?

A

Keeps the pipe and threading dies cool

99
Q

What is the purpose of gas Teflon tape on a pipe thread?

A

Lubricate the joint

100
Q

What is the amperage of a 120 volt circuit that has a 10 ohm light and a 50 ohm fan motor wired in series?

A

Add up the ohms and divide this into the volts to get the amps.
10 + 50 = 60 ohms
120/60 = 2 amps

101
Q

What is the voltage of a series circuit with 4-15 ohm lights and a 5 amp draw?

A

Add up ohms and multiply by the amperage.
15 + 15 + 15 + 15 = 60 ohms
60 x 5 = 300 volts

102
Q

What is the purpose of a draft hood in a gas appliance?

A

Prevents down drafts from enter the heat exchanger

103
Q

From the list, which safety switch automatically resets?
Roll out
Spill
Blocked vent
Main high limit

A

Main high limit-once cabinet cools down, the limit switch will reset.

104
Q

What is the area of the common manifold when venting 2 or more regulators together, with internal relief?

A

The manifold (single vent line) has an area equal to the largest relief valve opening plus 50% of the total area of the other relief valve openings.

105
Q

What can cause damage to the copper fins of a heat exchanger on a boiler?

A

Low or no water

106
Q

How do you set the heat anticipator on a thermostat?

A

The amp draw stated on the gas valve

107
Q

What is formed when you chemically combine 2 elements?

A

A compound

2nd year sheet metal (5 decks)

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