NATE Oil Heating

Question 1

What component in an oil burner atomizes the fuel oil and mixes it with air for combustion?

Accepted Answer

Nozzle

Answer

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?

Accepted Answer

Sense the presence or absence of a flame by its resistance to light

Answer

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?

Accepted Answer

Allow a limited time for ignition then shut down the burner if no flame is proven

Answer

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?

Accepted Answer

Replacing the nozzle and cleaning the strainer, electrodes, and heat exchanger

Answer

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?

Accepted Answer

Carbon soot level in flue gases by comparing a filter paper sample to a standard scale

Answer

The smoke tester draws flue gas through filter paper; the resulting stain is compared to a numbered scale (0 = clean, 9 = heavy smoke).

NATE - North American Technician Excellence Practice Test