Ontario Oil Burner Technician 3 (OBT3)
Certification Exam Questions and
Answers | 2026 Update | 100% Correct
Instant Download Pdf
1. A technician is installing a new oil storage tank indoors. What is the minimum
distance required from the tank to a source of ignition, such as a furnace or water
heater?
a) 1 metre
b) 2 metres
c) 3 metres
d) 5 metres
Rationale: The correct answer is a) 1 metre. The Ontario Building Code and CSA B139
stipulate a minimum separation of 1 metre (3.3 feet) between an oil storage tank and
any potential ignition source, such as a furnace, water heater, or electrical panel. This
distance is critical to prevent fire or explosion if a leak occurs. Placing the tank closer
than this is a serious code violation and a significant safety hazard.
2. What is the maximum allowable working pressure for a low-pressure oil burner
system, as defined in CSA B139?
a) 5 psi
b) 15 psi
c) 30 psi
d) 75 psi
,Rationale: The correct answer is a) 5 psi. CSA B139 specifically defines a low-pressure
system as one where the maximum oil pressure does not exceed 5 psi (34.5 kPa). This
classification is critical because it dictates the type of piping, fittings, and valves that
must be used. Systems operating above this pressure are considered high-pressure and
are subject to different, more stringent installation requirements.
3. A Beckett NX burner is firing with a steady flame but a pulsating sound is
coming from the burner motor. What is the most likely cause?
a) A clogged fuel nozzle
b) A failing burner motor coupling
c) A cracked flame retention head
d) An improperly set electrode gap
Rationale: The correct answer is b) A failing burner motor coupling. A pulsating
sound, particularly on a Beckett NX or similar models with a PSC motor and a coupling,
often indicates that the motor coupling is worn, loose, or breaking. This coupling
connects the motor shaft to the fuel pump. As it fails, it can cause the pump to
momentarily bind and release, creating a rhythmic pulsation. A clogged nozzle would
typically cause a weak or smoky flame, not a pulsating mechanical sound.
4. According to CSA B139, what is the minimum size of a vent pipe from an oil
storage tank?
a) 1/4 inch (6.4 mm)
b) 3/8 inch (9.5 mm)
c) 1/2 inch (12.7 mm)
d) 2 inches (50.8 mm)
Rationale: The correct answer is d) 2 inches (50.8 mm). The vent pipe for an oil
storage tank must be a minimum of 2 inches in diameter. This larger size is essential to
prevent the vent from becoming obstructed by frost, ice, or debris, ensuring that air can
freely enter the tank as oil is drawn out. An undersized or blocked vent can cause the
tank to collapse under vacuum or lead to a loss of oil supply to the burner.
,5. A technician finds a small drip from a flare fitting on an oil line. What is the
correct repair procedure?
a) Tighten the fitting until the drip stops.
b) Replace the copper tubing and flare nut.
c) Disassemble, inspect, and remake the flare if necessary.
d) Apply pipe dope to the outside of the fitting.
Rationale: The correct answer is c) Disassemble, inspect, and remake the flare if
necessary. A leaking flare fitting is often caused by a damaged flare face, a cracked flare
nut, or insufficient torque. Over-tightening a fitting can split the flare or damage the nut.
The proper procedure is to disassemble, inspect the flare and seat for defects, and
remake the flare if any imperfection is found. Pipe dope is for threaded (NPT) fittings,
not flare fittings.
6. What is the primary purpose of a fusible link in an oil-fired appliance?
a) To shut off the burner if the stack temperature exceeds a set point.
b) To shut off the oil supply in the event of a fire.
c) To prevent the appliance from over-pressurizing.
d) To provide a manual emergency shut-off.
Rationale: The correct answer is b) To shut off the oil supply in the event of a fire. A
fusible link is a safety device, often located in the oil supply line near the burner or tank.
It is designed to melt at a specific temperature (typically 165-212°F or 74-100°C) in the
event of a fire. When it melts, it closes a valve or activates a mechanism to immediately
shut off the oil supply, preventing the fire from being fed by the fuel source.
7. A high-efficiency oil-fired furnace has a sealed combustion system. What is the
primary benefit of this design?
a) It eliminates the need for a chimney.
b) It increases the system's AFUE rating.
c) It improves safety by preventing flame rollout.
d) It simplifies the venting installation.
, Rationale: The correct answer is c) It improves safety by preventing flame rollout. A
sealed combustion system uses a dedicated pipe to draw combustion air from outside
the building. This creates a closed loop: air in from outside, products of combustion out.
By not using indoor air for combustion, it eliminates the risk of backdrafting or flame
rollout into the living space, especially in tightly sealed modern homes. While it does
contribute to higher efficiency and can allow for side-wall venting, its primary safety
function is isolation from the indoor environment.
8. What is the typical oil pressure setting for a residential oil burner using a high-
static pressure nozzle?
a) 60 psi (414 kPa)
b) 100 psi (689 kPa)
c) 140 psi (965 kPa)
d) 200 psi (1379 kPa)
Rationale: The correct answer is b) 100 psi (689 kPa). While some systems may be set
as low as 80 psi or as high as 140 psi, 100 psi is the standard nominal pressure for most
residential oil burners. The nozzle's flow rate is rated at 100 psi (e.g., a 0.75 GPH nozzle
at 100 psi). Changing the pump pressure is a common way to adjust the firing rate, and
it must be done in conjunction with proper combustion testing.
9. During a routine service, you measure a stack temperature of 650°F (343°C) on a
conventional cast-iron boiler. The CO2 is at 12% and the smoke reading is a Trace.
What is the most likely issue?
a) The burner is over-fired.
b) The heat exchanger is sooted.
c) The burner is under-fired.
d) The combustion air is insufficient.
Rationale: The correct answer is b) The heat exchanger is sooted. A high stack
temperature combined with good CO2 (12%) and a low smoke reading (Trace) indicates
that heat is not being effectively transferred from the combustion gases to the water.
Certification Exam Questions and
Answers | 2026 Update | 100% Correct
Instant Download Pdf
1. A technician is installing a new oil storage tank indoors. What is the minimum
distance required from the tank to a source of ignition, such as a furnace or water
heater?
a) 1 metre
b) 2 metres
c) 3 metres
d) 5 metres
Rationale: The correct answer is a) 1 metre. The Ontario Building Code and CSA B139
stipulate a minimum separation of 1 metre (3.3 feet) between an oil storage tank and
any potential ignition source, such as a furnace, water heater, or electrical panel. This
distance is critical to prevent fire or explosion if a leak occurs. Placing the tank closer
than this is a serious code violation and a significant safety hazard.
2. What is the maximum allowable working pressure for a low-pressure oil burner
system, as defined in CSA B139?
a) 5 psi
b) 15 psi
c) 30 psi
d) 75 psi
,Rationale: The correct answer is a) 5 psi. CSA B139 specifically defines a low-pressure
system as one where the maximum oil pressure does not exceed 5 psi (34.5 kPa). This
classification is critical because it dictates the type of piping, fittings, and valves that
must be used. Systems operating above this pressure are considered high-pressure and
are subject to different, more stringent installation requirements.
3. A Beckett NX burner is firing with a steady flame but a pulsating sound is
coming from the burner motor. What is the most likely cause?
a) A clogged fuel nozzle
b) A failing burner motor coupling
c) A cracked flame retention head
d) An improperly set electrode gap
Rationale: The correct answer is b) A failing burner motor coupling. A pulsating
sound, particularly on a Beckett NX or similar models with a PSC motor and a coupling,
often indicates that the motor coupling is worn, loose, or breaking. This coupling
connects the motor shaft to the fuel pump. As it fails, it can cause the pump to
momentarily bind and release, creating a rhythmic pulsation. A clogged nozzle would
typically cause a weak or smoky flame, not a pulsating mechanical sound.
4. According to CSA B139, what is the minimum size of a vent pipe from an oil
storage tank?
a) 1/4 inch (6.4 mm)
b) 3/8 inch (9.5 mm)
c) 1/2 inch (12.7 mm)
d) 2 inches (50.8 mm)
Rationale: The correct answer is d) 2 inches (50.8 mm). The vent pipe for an oil
storage tank must be a minimum of 2 inches in diameter. This larger size is essential to
prevent the vent from becoming obstructed by frost, ice, or debris, ensuring that air can
freely enter the tank as oil is drawn out. An undersized or blocked vent can cause the
tank to collapse under vacuum or lead to a loss of oil supply to the burner.
,5. A technician finds a small drip from a flare fitting on an oil line. What is the
correct repair procedure?
a) Tighten the fitting until the drip stops.
b) Replace the copper tubing and flare nut.
c) Disassemble, inspect, and remake the flare if necessary.
d) Apply pipe dope to the outside of the fitting.
Rationale: The correct answer is c) Disassemble, inspect, and remake the flare if
necessary. A leaking flare fitting is often caused by a damaged flare face, a cracked flare
nut, or insufficient torque. Over-tightening a fitting can split the flare or damage the nut.
The proper procedure is to disassemble, inspect the flare and seat for defects, and
remake the flare if any imperfection is found. Pipe dope is for threaded (NPT) fittings,
not flare fittings.
6. What is the primary purpose of a fusible link in an oil-fired appliance?
a) To shut off the burner if the stack temperature exceeds a set point.
b) To shut off the oil supply in the event of a fire.
c) To prevent the appliance from over-pressurizing.
d) To provide a manual emergency shut-off.
Rationale: The correct answer is b) To shut off the oil supply in the event of a fire. A
fusible link is a safety device, often located in the oil supply line near the burner or tank.
It is designed to melt at a specific temperature (typically 165-212°F or 74-100°C) in the
event of a fire. When it melts, it closes a valve or activates a mechanism to immediately
shut off the oil supply, preventing the fire from being fed by the fuel source.
7. A high-efficiency oil-fired furnace has a sealed combustion system. What is the
primary benefit of this design?
a) It eliminates the need for a chimney.
b) It increases the system's AFUE rating.
c) It improves safety by preventing flame rollout.
d) It simplifies the venting installation.
, Rationale: The correct answer is c) It improves safety by preventing flame rollout. A
sealed combustion system uses a dedicated pipe to draw combustion air from outside
the building. This creates a closed loop: air in from outside, products of combustion out.
By not using indoor air for combustion, it eliminates the risk of backdrafting or flame
rollout into the living space, especially in tightly sealed modern homes. While it does
contribute to higher efficiency and can allow for side-wall venting, its primary safety
function is isolation from the indoor environment.
8. What is the typical oil pressure setting for a residential oil burner using a high-
static pressure nozzle?
a) 60 psi (414 kPa)
b) 100 psi (689 kPa)
c) 140 psi (965 kPa)
d) 200 psi (1379 kPa)
Rationale: The correct answer is b) 100 psi (689 kPa). While some systems may be set
as low as 80 psi or as high as 140 psi, 100 psi is the standard nominal pressure for most
residential oil burners. The nozzle's flow rate is rated at 100 psi (e.g., a 0.75 GPH nozzle
at 100 psi). Changing the pump pressure is a common way to adjust the firing rate, and
it must be done in conjunction with proper combustion testing.
9. During a routine service, you measure a stack temperature of 650°F (343°C) on a
conventional cast-iron boiler. The CO2 is at 12% and the smoke reading is a Trace.
What is the most likely issue?
a) The burner is over-fired.
b) The heat exchanger is sooted.
c) The burner is under-fired.
d) The combustion air is insufficient.
Rationale: The correct answer is b) The heat exchanger is sooted. A high stack
temperature combined with good CO2 (12%) and a low smoke reading (Trace) indicates
that heat is not being effectively transferred from the combustion gases to the water.
