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Furnace Commsioning > Standard Furnace Components > Flashcards

Standard Furnace Components Flashcards

1
Q

List the different configurations of a furnace

A

Up flow
Down flow
Horizontal

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2
Q

Why is a thermostat better for controlling the furnace than a light switch

A

Set to turn on when the temperature drops below a certain temperature

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3
Q

One there is a call for heat in a furnace what happens next

A

Completes electrical circuit that opens gas valve

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4
Q

3 examples of operating controls

A

Thermostats
Fan controls
Transformers
Gas valves
Motors

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5
Q

Give 3 examples of safety controls

A

Limit switches
Thermocouple

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6
Q

List the different types of standing pilots

A

Aerated
Post aerated
Non aerated

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7
Q

What is the range of voltage that a thermal couple can produce

A

20-30 millivolts dc when heated

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8
Q

How much should the flame surround the thermal couple tip

A

3/8- 1/2

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9
Q

Define thermopile

A

Thermocouples wired in series

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10
Q

Another name for thermopile

A

Power pills or pilot generators

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11
Q

What components make up the flame safeguard

A

Disc, plunger, dropout spring, pole piece, electro magnet

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12
Q

What energizes the power unit

A

Power from the thermocouple energizes the electromagnet in the power unit

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13
Q

What keeps the plunger in the power unit closed

A

Electro magnet

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14
Q

Combination gas valve components, list them

A

On pilot off knob
Pressure regulator
Power unit
Thermocouple connection
Pilot adjustment
Electrical connections
Operator
Pilot connection
Gas inlet
Gas outlet
Pressure tap

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15
Q

What is normally used to detect temperature in a temperature sensing device

A

Bi metal strip expands and contracts
Hot junction and cold junction

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16
Q

List the different types of temperature sensing devices

A

Strip type
Spiral type
Disc type
Bellows type
Liquid bulb type

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17
Q

What are different categories of thermostats

A

Mechanical
Electronically

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18
Q

What are the possible contacts in a mechanical thermostat

A

Mercury bulb

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19
Q

Describe the purpose for a heat anticipator

A

Prevents temperature overshooting

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20
Q

The variable heat anticipator need to be set to match what

A

Must Match the current draw of the control circuit

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21
Q

Electronic thermostats use what type of temperature sensor

A

Thermistor

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22
Q

List the possible ways that an electronic thermostat receives power

A

Can be battery powered or powered from the control circuit ( power stealing)

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23
Q

What’s an advantage about a programmable thermostat

A

Program different times you want the heat on

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24
Q

List the setting for fan control

A

Fan on: between 120-140
Fan off: between 90-100

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25
Q

If a high limit control were to open what would it cut power too

A

Gas valve will lose power and close stopping flow of gas

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26
Q

Where are roll out switches located

A

Above the burners

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27
Q

What does a combination fan/ limit control use for temperature sensing device

A

Bi metal

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28
Q

What is the max temperature setting for a high limit switch

A

250f

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29
Q

Describe the primary windings in a transformer

A

Connected to the power source which brings power into the transformer, wraps around an iron core

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30
Q

Describe the secondary winding in a transformer

A

Also wraps around the core and is used to power a load

31
Q

How does a transformer operate

A

Magnetic induction

32
Q

What style of transformer is used more often in hvac

A

Step up transformer

33
Q

How are transformers rated

A

Va rating (volts x amps = watts

34
Q

List the parts in a fan belt driven motor

A

Shaft, keeper, pulley

35
Q

Describe heat exchanger

A

Transfers heat produced by burners

36
Q

What is the purpose of a draft diverter

A

Provides a pressure balanced flue

37
Q

What is the job of a burner

A

Transforms combustible fuel into heat

38
Q

What are the two different types of burners

A

Up shot
In shot

39
Q

List the parts of a burner

A

Mixer head
Mixer face
Primary air shutter
Mixer throat
Venturi tube
Orifice
Burner ports
Burner head

40
Q

What regulates the amount of air entering a burner

A

Primary air shutter

41
Q

List what information can be found on a rating plate

A

Approval agency
Orifice sizes
Altitude
I put rating
Fuel type
Electrical requirements

42
Q

How many milivolts are in 1 volt

A

1/1000 v

43
Q

What is the most common thermopile voltage

A

750 milivolts

44
Q

Which way should the ladder diagram be read

A

Left to right

45
Q

When a schematic is shown is the power on or off

A

Power off

46
Q

A milivolt system is good because it can run a control system without the presence of line voltage, what are the disadvantages

A

Amount of controls it can operate
Length of wire
Power generated by thermopile weakens over time

47
Q

What color is the hot wire in an electrical circuit

A

Black

48
Q

What color is neutral in a electrical circuit

A

White

49
Q

What are our limits when working with electricity

A

Servicing or changing controls
Repairing wires
Making minor upgrades to existing hvac systems

50
Q

Who should work on electrical panels

A

Electricians

51
Q

What does a flow chart represent

A

The process of how the equiptment operates

52
Q

What is the Sequence of operation for a furnace

A

Pilot on

Call for heat

Burner ignite

Fan comes on

System runs until call for heat ends

Thermostat reaches temp ending call for heat

Burner shuts down fan keeps running

Fan shuts down ending heat cycle

53
Q

What is an expanding pilot

A

Hybrid of continuous pilot, flame is always lit but at a much smaller size than required

54
Q

What is the difference between an intermittent and an interrupted pilot

A

Only ignited when there is a call for main burner ignition- pilot flame extinguishes when main burner has been ignited

55
Q

What does HSI stand for

A

Hot surface ignition

56
Q

What is the most common pilot used in todays industry

A

Aerated

57
Q

What is the color of the pilot orifices for natural gas and propane gas

A

Silver and brown

58
Q

All pilots must be equipped with?

A

Mounting brackets

59
Q

Thermocouples have ?

A

Hot and cold junctions

60
Q

What is a safety shut down test

A

Disconnecting the thermocouple lead from the control, main burner shoild shut off

61
Q

What is another name for a high limit switch

A

ECO energy shut off

62
Q

A flame should enevelop the thermocouple how much

A

3/8 to 1/2

63
Q

What color should the flame be on a pilot light

A

Blue as possible

64
Q

A thermocouple should read what on an open circuit

A

32 open 17 closed

65
Q

The response time on a gas valve should not exceed how much time

A

180 seconds for standing pilot appliances up to 400 MBH

66
Q

What does a step down transformer do and how is it rated

A

Steps down voltage from 120 to 24
It is Va rated

67
Q

What type of control is a fan switch

A

Operating

68
Q

How can an appliance be denergized

A

Door switch, breaker, furnace switch

69
Q

Name three instruments used to determine gas pressure of an appliance

A

U tube, digital, analog

70
Q

What is the proper manifold pressure for natural gas

A

3.5” wc

71
Q

What is the proper manifold pressure for propane

A

11” wc

72
Q

How can you test a transformer to see if it’s functional

A

Continuity test

73
Q

What are the three designations for the wires in the line voltage circuit

A

Hot, neutral, ground

Furnace Commsioning (3 decks)

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