NATE Oil Heating 1 — Questions and Answers
Question 1: What component in an oil burner atomizes the fuel oil and mixes it with air for combustion?
- Electrodes
- Nozzle (Correct answer)
- Oil pump
- Cad cell
Correct answer: Nozzle
The nozzle atomizes oil into a fine spray at a precise angle and pattern, mixing it with combustion air for efficient burning.
Question 2: What is the function of the cad cell (cadmium sulfide cell) in an oil burner primary control?
- Measure oil pump pressure
- Sense the presence or absence of a flame by its resistance to light (Correct answer)
- Control the firing rate of the burner
- Monitor stack temperature
Correct answer: Sense the presence or absence of a flame by its resistance to light
The cad cell changes resistance based on light; in darkness (no flame) its high resistance signals the primary control to initiate lockout.
Question 3: What is the primary control's 'safety timing' function on an oil furnace?
- Prevent the burner from firing more than 3 times per hour
- Allow a limited time for ignition then shut down the burner if no flame is proven (Correct answer)
- Control circulator pump timing
- Purge the combustion chamber before ignition
Correct answer: Allow a limited time for ignition then shut down the burner if no flame is proven
Safety timing (typically 45–90 seconds) limits how long unburned oil can accumulate before locking out the burner to prevent explosion.
Question 4: What annual maintenance item is most critical for oil burner efficiency?
- Replacing the transformer
- Replacing the nozzle and cleaning the strainer, electrodes, and heat exchanger (Correct answer)
- Adjusting the thermostat anticipator
- Flushing the oil tank
Correct answer: Replacing the nozzle and cleaning the strainer, electrodes, and heat exchanger
An annual tune-up including nozzle replacement and cleaning ensures complete combustion, maximum efficiency, and safe operation.
Question 5: What does a smoke tester (Bacharach pump) measure on an oil burner?
- Stack gas CO2 percentage
- Carbon soot level in flue gases by comparing a filter paper sample to a standard scale (Correct answer)
- Combustion air temperature
- Oil pump pressure
Correct answer: Carbon soot level in flue gases by comparing a filter paper sample to a standard scale
The smoke tester draws flue gas through filter paper; the resulting stain is compared to a numbered scale (0 = clean, 9 = heavy smoke).
Question 6: What is the typical oil pump pressure setting for a residential oil burner?
- 50–60 PSI
- 100–150 PSI (Correct answer)
- 200–300 PSI
- 25–40 PSI
Correct answer: 100–150 PSI
Residential oil burner pumps typically operate at 100–150 PSI (commonly 100 PSI) to properly atomize the fuel through the nozzle.
NATE Oil Heating 1
What component in an oil burner atomizes the fuel oil and mixes it with air for combustion?