Quiz on Electronic Controls and Ignition Sequences

What initiates the call for heat in a forced-air furnace?

• The pressure switch closes

• The room thermostat senses a drop in temperature

• The ignition module powers up

• The main burner lights

What happens if the ignition module senses a flame during the safe-start check?

• The main burner ignites

• The pilot gas valve opens

• The system goes into lockout

• The ignition sequence continues

What is required for the ignition of the pilot in an intermittent pilot spark system?

• Only a source of ignition

• Only fuel (gas)

• Both fuel (gas) and a source of ignition

• A functioning thermostat

What occurs after the pilot flame is proven in an intermittent pilot spark system?

• The main burner ignites immediately

• The spark generator circuit shuts off

• The system goes into lockout

• The pilot gas valve shuts off

What is the purpose of the post purge cycle in some furnaces?

• To ignite the main burner

• To clear unburned gas from the combustion chamber

• To shut off the pilot gas

• To maintain the pilot flame

What happens if the pilot is not proved within the lockout timer's allotted time?

• The main burner ignites

• The system continues to try igniting

• The module shuts off the gas and spark

• The thermostat resets

How can a module be reset after a lockout?

• By closing the R-W terminals

• By waiting for one minute and turning the power back on

• By replacing the ignition module

• By turning off the thermostat

What is a characteristic of modules with continuous trial for ignition?

• They only try to ignite once

• They can be used on propane appliances

• They keep the pilot gas on indefinitely if there is no flame

• They require a manual reset after lockout

What is the first step in the direct spark ignition sequence?

• The main burner lights

• The pressure switch opens

• The ignition module powers up

• The thermostat senses a drop in temperature

What is the purpose of the flame sensor circuit?

• To control the induced fan

• To sense the pilot flame through flame rectification

• To ignite the pilot flame

• To shut off the gas valve