Electric Ignition Flashcards
Electronic ignition can be configured several ways. What are they
Intermittent using spark
Intermittent using hot surface
Direct ignition using spark
Direct ignition using hot surface
Describe interrupted pilot ignition
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
Describe intermittent
It is similar to interrupted, but the pilot stays on during burner cycle
Intermittent and interrupted are spark ignited but there is a what
24v hot surface intermittent pilot ignition system using a “smart valve”
Difference between intermittent spark ignition and pilot
Works the same. the only difference is that the pilot is ignited. One ignites burners by fire the other by a spark plug
Recommend spark gap
1/8”
Which hot surface is better silicon carbide or nitride and why?
Nitride is better. It has a life span of 6 to ten years or double what carbide has.
Two main principles in flame rod detection system
Flame rectification and flame conductivity
Define flame rectification
Rectification means change is uses a device for converting AC into DC. The flame and flame rod/ground become this device.
Why aren’t flame conductivity tests used any more
Can differentiate the difference between flame current and short circuit
Ground to flame sensor ratio
4 to 1 ground to flame sensor area
Why is it better to have the 4:1 ratio
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.
How to clean the flame rod
Use scotch brite pad or 000 steel wool only
How to clean the flame rod
Use scotch brite pad or 000 steel wool only
How long does it take an hsi to warm up and to what approx temp
17-34 seconds 2600f°
What does PL mean on a diagram
Plug connection
Role of the cpu in a furnace
Controls the operation of the appliance and sequences, ignition, firing of burner and monitors safety controls
What is RWGYC in a thermostat
R=POWER
W=HEAT
G=FAN
Y=COOLING
C=COMMON
When blower is energized how long is the delay
90 to 180 seconds
The blower off delay is adjustable, what’s the range
90 to 240
What is a ground surface for, why isn’t it arcing to the main burner
For the spark to arc to instead of on the main burner, it will blow a hole in the burner over time
Over time, what can build up on an HSI
An oxide coating
Instead of a pilot proving flame what does a DSI do
Turns on main burner gas, lights the main burner, and proves this flame
On some furnaces, the inducer continues to run after burners are shut down. What is this called what’s it for
Post purge cycle, gets rid of the remaining products of combustion
How are ladder diagrams drawn?
Unit on standby and powered but with no call for heat
When using an electronic ignition, what is the process of proving the flame called
Flame rectification
What is the minimum flame to ground ratio
1:4
Why have flame conductivity systems not been used for proving flames?
Can’t distinguish between a flame or a ground short
What is the first step in the sequence of operation
Call for heat at the thermostat
What is the importance of the connection diagram
It shows where the wires go and the color of the wires
What is the importance of the ladder diagram
It shows how the appliance works for troubleshooting
