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Furnace Commisioning > Electric Ignition > Flashcards

Electric Ignition Flashcards

1
Q

Electronic ignition can be configured several ways. What are they

A

Intermittent using spark
Intermittent using hot surface
Direct ignition using spark
Direct ignition using hot surface

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2
Q

Describe interrupted pilot ignition

A

The main burner and pilot are off during standby. Call for heat ignites pilot, then burners, system proves burner is lit then pilot turns off

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3
Q

Describe intermittent

A

It is similar to interrupted, but the pilot stays on during burner cycle

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4
Q

Intermittent and interrupted are spark ignited but there is a what

A

24v hot surface intermittent pilot ignition system using a “smart valve”

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5
Q

Difference between intermittent spark ignition and pilot

A

Works the same. the only difference is that the pilot is ignited. One ignites burners by fire the other by a spark plug

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6
Q

Recommend spark gap

A

1/8”

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7
Q

Which hot surface is better silicon carbide or nitride and why?

A

Nitride is better. It has a life span of 6 to ten years or double what carbide has.

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8
Q

Two main principles in flame rod detection system

A

Flame rectification and flame conductivity

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9
Q

Define flame rectification

A

Rectification means change is uses a device for converting AC into DC. The flame and flame rod/ground become this device.

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10
Q

Why aren’t flame conductivity tests used any more

A

Can differentiate the difference between flame current and short circuit

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11
Q

Ground to flame sensor ratio

A

4 to 1 ground to flame sensor area

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12
Q

Why is it better to have the 4:1 ratio

A

Because of the difference in electrodes sizes, more current flows in one direction than the other, creating a pulsating DC current, which the flame proving circuit requires.

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13
Q

How to clean the flame rod

A

Use scotch brite pad or 000 steel wool only

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14
Q

How to clean the flame rod

A

Use scotch brite pad or 000 steel wool only

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15
Q

How long does it take an hsi to warm up and to what approx temp

A

17-34 seconds 2600f°

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16
Q

What does PL mean on a diagram

A

Plug connection

17
Q

Role of the cpu in a furnace

A

Controls the operation of the appliance and sequences, ignition, firing of burner and monitors safety controls

18
Q

What is RWGYC in a thermostat

A

R=POWER
W=HEAT
G=FAN
Y=COOLING
C=COMMON

19
Q

When blower is energized how long is the delay

A

90 to 180 seconds

20
Q

The blower off delay is adjustable, what’s the range

A

90 to 240

21
Q

What is a ground surface for, why isn’t it arcing to the main burner

A

For the spark to arc to instead of on the main burner, it will blow a hole in the burner over time

22
Q

Over time, what can build up on an HSI

A

An oxide coating

23
Q

Instead of a pilot proving flame what does a DSI do

A

Turns on main burner gas, lights the main burner, and proves this flame

24
Q

On some furnaces, the inducer continues to run after burners are shut down. What is this called what’s it for

A

Post purge cycle, gets rid of the remaining products of combustion

25
Q

How are ladder diagrams drawn?

A

Unit on standby and powered but with no call for heat

26
Q

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

A

Flame rectification

27
Q

What is the minimum flame to ground ratio

A

1:4

28
Q

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

A

Can’t distinguish between a flame or a ground short

29
Q

What is the first step in the sequence of operation

A

Call for heat at the thermostat

30
Q

What is the importance of the connection diagram

A

It shows where the wires go and the color of the wires

31
Q

What is the importance of the ladder diagram

A

It shows how the appliance works for troubleshooting

Furnace Commisioning (6 decks)

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