OFTEC Oil Burner Types and Operation 1 — Questions and Answers
Question 1: Which type of oil burner atomises fuel by forcing it through a nozzle under high pressure?
- Pressure jet burner (Correct answer)
- Vaporising burner
- Rotary cup burner
- Pot burner
Correct answer: Pressure jet burner
A pressure jet burner uses a pump to force oil through a fine nozzle at high pressure (typically 7-10 bar), creating a spray pattern that mixes with air for efficient combustion.
Question 2: What is the typical fuel pump pressure for a domestic pressure jet oil burner?
- 7-10 bar (Correct answer)
- 1-3 bar
- 15-20 bar
- 25-30 bar
Correct answer: 7-10 bar
Domestic pressure jet burners typically operate at 7-10 bar pump pressure. This pressure is sufficient to atomise the kerosene through the nozzle for clean combustion.
Question 3: What grade of oil is most commonly used in UK domestic oil-fired heating systems?
- 28-second kerosene (Class C2) (Correct answer)
- 35-second gas oil (Class D)
- Light fuel oil (Class E)
- Heavy fuel oil (Class G)
Correct answer: 28-second kerosene (Class C2)
28-second kerosene (BS 2869 Class C2) is the standard fuel for domestic oil heating in the UK. It is cleaner burning than gas oil and suitable for pressure jet and vaporising burners.
Question 4: What is the primary function of the photocell in a pressure jet oil burner?
- To detect the presence of a flame (Correct answer)
- To ignite the fuel
- To regulate fuel pressure
- To control the fan speed
Correct answer: To detect the presence of a flame
The photocell (flame sensor) detects UV or visible light from the burner flame. If no flame is detected within the lockout period, the burner control box shuts down the system for safety.
Question 5: In a vaporising burner, how is the oil prepared for combustion?
- By heating it on a hot surface until it turns to vapour (Correct answer)
- By forcing it through a high-pressure nozzle
- By spinning it off a rotating cup
- By mixing it with compressed air in a venturi
Correct answer: By heating it on a hot surface until it turns to vapour
Vaporising burners work by allowing oil to flow onto a heated surface (the pot or sleeve) where it evaporates. The vapour then mixes with air and burns. They are simpler but less common than pressure jet types.
Question 6: What does a lockout condition on an oil burner indicate?
- The burner has failed to establish a flame and has shut down for safety (Correct answer)
- The thermostat has reached its set temperature
- The fuel tank is full
- The flue temperature is too high
Correct answer: The burner has failed to establish a flame and has shut down for safety
A lockout occurs when the burner control box fails to detect a flame within a set time period (typically 15-45 seconds). This is a safety feature preventing unburnt oil from accumulating. Manual reset is required.
OFTEC Oil Burner Types and Operation 1
Which type of oil burner atomises fuel by forcing it through a nozzle under high pressure?