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Furnace Commisioning > Pilots, Pilot Burners, Thermocouples And Thermopiles > Flashcards

Pilots, Pilot Burners, Thermocouples And Thermopiles Flashcards

1
Q

4 types of pilots

A

Continuous
Expanding
Intermittent
Interrupted

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2
Q

A continuous pilot( also known as_____) burns 24/7

A

Standing pilot

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3
Q

What is an expanding pilot and how does it work

A

Hybrid of a continuous, the flame is always lit but at a much smaller size. Increases in size when there’s a call for heat

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4
Q

What is an intermittent pilot

A

Only ignited when there is a call for heat usually by spark, pilot remains on throughout burner cycle and is extinguished when main burner cycles off

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5
Q

What is an interrupted pilot

A

Similar to interment pilots, expect that the pilot extinguishes when the main burner has ignited, monitored by a separate flame sensor

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6
Q

Where are non aerated pilots found use what type of air

A

Clothes dryers and gas cooking
Secondary

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7
Q

Pilot orifices are what color for natural gas and propane, which one has the larger orifices

A

Nat gas is silver metallic
Propane is brass
Nat gas has the larger orifices

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8
Q

Most common pilot light is?

A

The post aerated pilot light

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9
Q

What are the main functions of the pilot

A

Ensure ignition of main burner and main safety device with thermocouple

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10
Q

Secondary Safety feature in pilots is called, what does it do

A

Proved pilot, shuts off main burner, and sometimes pilot burner

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11
Q

Difference between safe hook up and 100% safe hook up

A

Safe hook up main burner gas is shut off pilot gas is not. 100% turns off pilot light and main burner

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12
Q

You should always replace the thermopile with the same millvoltage out put. True or false

A

True

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13
Q

How long does it take the thermocouple to heat up

A

30 to 60 seconds

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14
Q

All propanes system must be a safe hook up or 100% safe hook up

A

100% safe hook up

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15
Q

How tight do you turn a thermocouple connection

A

No more than one quarter turn beyond finger tight

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16
Q

What is an ECO

A

Energy cut off switch, another name for high limit

17
Q

Why do thermopiles have extra voltage

A

Used to operate both the safety device and control valve to main burner

18
Q

What happens if your thermocouple gets excessive heat

A

Excessive heat will prematurely burn out thermocouple

19
Q

What is the acceptable voltage range for an open circuit

A

17mv to 32mv

20
Q

What is the acceptable voltage range for an closed circuit what is needed to complete the test

A

A test adapter is needed
8mv to 17mv

21
Q

Drop out range is, what does that mean for the thermocoupler

A

0.75mv to 6 mV, needs to be replaced

22
Q

If a gas valve fails, what position does it fail in?

A

Closed

23
Q

When should the turndown test be done?

A

On appliances under
And exceeding 400mbh

24
Q

Response time shall not exceed how long? Can be detected by?

A

180 seconds, an audible click as gas valve snaps closed.

25
Q

What is response time

A

The time it takes the thermocouple to cool and cause the power unit to de-energize gas valve

26
Q

What will happen if the relief port is blocked in a diaphragm gas valve?

A

Pressure can not escape, and the valve remains closed

27
Q

What position does the actuator in a diaphragm gas valve end up if the diaphragm ruptures?

A

The actuator remains closed

28
Q

Junctions of a thermocouple are called

A

Hot and cold

29
Q

If mV fall into this range What should you do

A

Check pilot flame and electrical connections

30
Q

What are these 5 descriptions on the test chart

A
  1. Check pilot flame and electrical connects
    2.acceptable range
    3.check power unit
    4.replace thermo coupler
    5.drop out range
31
Q

All pilots must be equipped with what

A

A mounting bracket and fastened on main burner to ensure satisfactory ignition.

32
Q

What are orifices designed to do

A

Control Gas flow

33
Q

What high limit safety switch comes with a manual rest

A

Flame rollout

34
Q

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

A

⅛”

35
Q

What happens if the burner flame impinges on the burner or any other metal source

A

The flame will cool and cause incomplete combustion

36
Q

Describe aerated pilots

A

Uses primary air and a mixing tube

37
Q

Describe non aerated pilot

A

Uses only secondary air, slight yellow flame

38
Q

When converting nat gas to propane what do you need to do?

A

Change gas orifices, pilot orifices, gas valve

39
Q

When you depress the knob.on the gas vavle what happens.

A

The power unit closes the gas unit opens

Furnace Commisioning (10 decks)

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