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HVAC Troubleshooting > Electronic Ignition > Flashcards

Electronic Ignition Flashcards

1
Q

What is the main difference between an intermittent pilot gas valve and a direct ignition gas valve?

A

The direct ignition gas valve has no pilot connection.

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2
Q

When using electronic ignition, what is the process of proving the flame called?

A

Flame rectification

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3
Q

What is the minimum flame rod to ground electrode area that is immersed in the flame?

A

1:4

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4
Q

What is the minimum flame ground to rod electrode area that is immersed in the flame?

A

4:1

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5
Q

Why have flame conductivity systems not been used for proving the flame?

A

The system will not distinguish between a flame and a short to ground.

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6
Q

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

A

There is a call for heat at the thermostat.

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7
Q

What is the importance of the connection (pictorial) diagram?

A

It shows where the wires go and the colour of the wires.

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8
Q

What is the importance of the ladder (schematic) diagram?

A

It shows how the appliance works for troubleshooting.

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9
Q

What does intermittent mean in simple terms?

A

Sometimes

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10
Q

What does the HSI (Hot Surface Igniter) light?

A

The pilot

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11
Q

What does the pilot light?

A

The burners

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12
Q

What are 4 ways an electronic system can be configured?

A

Intermittent pilot using spark, Intermittent pilot using hot surface, direct ignition using spark, and direct ignition using hot surface.

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13
Q

In the interrupted pilot ignition system, the main burner and pilot are ___ during standby.

A

Off

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14
Q

What is the difference between the interrupted pilot ignition system and the intermittent pilot ignition system?

A

The difference is that the pilot is not extinguished after ignition of the main burner.

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15
Q

intermittent and interrupted pilot ignition systems are usually?

A

Spark-ignited

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16
Q

Most HSI’s (hot surface igniter) are how many volts?

A

120v or 80v

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17
Q

Hot surface ignition systems are usually?

A

Direct ignition

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18
Q

Describe what a HSI (hot surface igniter) does?

A

Ignites the main burner with a hot surface made out of silicon carbine.

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19
Q

Describe the flame rod and what it does?

A

It’s mounted and immersed in the main burner flame. Current is then passed from the module to the flame rod through the flame and returns current back to the module.

20
Q

What should you never do to a hot surface igniter?

A

Never touch it with your fingers as it will burn it out.

21
Q

What are the two main principles in flame rod detection systems?

A

Flame rectification and flame conductivity

22
Q

What is the definition of a rectifier?

A

It’s a device for converting alternating current into direct current.

23
Q

Describe flame ionization?

A

When heat from the flame causes the molecules between the electrodes to collide with each other so forcibly that some of the electrons are knocked out of the atoms, producing ions.

24
Q

Most burners are how many Btu’s per burner?

A

20,000 Btu’s per burner

25
Q

What is one of the only things in the cabinet that uses DC current?

A

The signal from the flame sensor to the HSI

26
Q

The larger the ratio to ground area to flame rod are, the ___ the flow of current in the proper direction.

A

Greater

27
Q

What is a recycling control?

A

More than one try for ignition

28
Q

Continuous trial for ignition is not allowed on propane appliances or direct ignition type systems. True or False?

A

True

29
Q

What is a post purge cycle?

A

When the inducer fans continues to run after the burners are shut off.

30
Q

A step down transformer is what two voltages?

A

A 120 VAC (line voltage) and a 24 VAC (control voltage) in most AC systems.

31
Q

What does ILK stand for?

A

Blower access panel interlock switch

32
Q

What does IDR stand for?

A

Induced draft motor relay

33
Q

The thermostat is connected to terminals?

A

R and W

34
Q

Terminal R is used for what?

A

It’s the hot terminal and is where the power from the transformer is connected.

35
Q

What does IDM stand for?

A

Induced draft motor

36
Q

What does PRS stand for?

A

Pressure switch

37
Q

What does LGPS stand for?

A

Low gas pressure switch

38
Q

What are the 4 terminals most thermostats have?

A

R, W, Y and G

39
Q

What is the W terminal used for?

A

Terminal that is used to energize the heating cycle

40
Q

What is one of the easiest devices to check and replace?

A

A fuse

41
Q

What device can be used to check the voltage drop across the load?

A

A voltmeter

42
Q

What fan speeds are normally used for heating modes?

A

Low and medium speeds

43
Q

The fan off delay setting is typically how many seconds?

A

90 seconds

44
Q

What are LEDs on the boards purpose?

A

Designed to flash in a certain sequence that indicates either a normal or a fault condition.

45
Q

What are two factors that should be checked when calibrating thermostats?

A

Operating temperature and operating differential

46
Q

When calibrating thermostats you should not use the thermometer built into the thermostat. True or False?

A

True, use a good quality thermometer instead.

47
Q

A combination gas valve incorporates which 3 major components?

A

A solenoid valve, a diaphragm, and a pressure regualtor.

HVAC Troubleshooting (6 decks)

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