BPI Combustion Safety 2 — Questions and Answers
Question 1: What is the primary purpose of a spillage test during a combustion safety evaluation?
- To measure CO output at the flue
- To determine if combustion gases are escaping into the living space (Correct answer)
- To check the heat exchanger for cracks
- To verify adequate gas pressure at the burner
Correct answer: To determine if combustion gases are escaping into the living space
A spillage test determines whether combustion gases are spilling from the appliance draft hood or diverter into the conditioned space instead of venting properly.
Question 2: Which condition is most likely to cause backdrafting in a naturally drafted water heater?
- Oversized flue pipe
- Negative pressure in the mechanical room due to exhaust fans (Correct answer)
- High outdoor temperatures in summer
- A fully open combustion air damper
Correct answer: Negative pressure in the mechanical room due to exhaust fans
Exhaust fans depressurize the building, creating negative pressure that can reverse flue draft and pull combustion gases into the living space.
Question 3: What CO concentration (ppm) in ambient air immediately requires evacuation and emergency response per BPI standards?
- 9 ppm
- 35 ppm
- 70 ppm
- Action level varies but life-safety response triggers at undiluted flue readings over 400 ppm with ambient spillage (Correct answer)
Correct answer: Action level varies but life-safety response triggers at undiluted flue readings over 400 ppm with ambient spillage
BPI protocols require immediate occupant evacuation and emergency service notification when undiluted flue CO exceeds 400 ppm and gases are spilling into the living area.
Question 4: A BPI analyst measures CO in the undiluted flue of a gas furnace and reads 250 ppm. What is the correct action?
- No action needed; 250 ppm is within acceptable limits
- Tag the unit as unsafe and advise the homeowner to have it serviced (Correct answer)
- Immediately evacuate the building and call 911
- Retest after running the furnace for 30 more minutes
Correct answer: Tag the unit as unsafe and advise the homeowner to have it serviced
BPI's action level for undiluted flue CO is over 400 ppm; at 250 ppm the unit is elevated but below immediate life-safety threshold, so the analyst tags it and recommends HVAC service.
Question 5: What does the Building Performance Institute define as 'worst-case depressurization'?
- The pressure measured at the gas meter during peak demand
- The most negative pressure achievable in the combustion appliance zone under realistic operating conditions (Correct answer)
- The pressure drop across a dirty air filter
- Outdoor wind pressure acting on the windward wall
Correct answer: The most negative pressure achievable in the combustion appliance zone under realistic operating conditions
Worst-case depressurization is the maximum negative pressure that can be induced in the combustion appliance zone by simultaneously operating all exhaust equipment and closing interior doors.
Question 6: Which instrument is required to measure worst-case depressurization in a combustion appliance zone?
- Combustion analyzer
- Digital manometer (Correct answer)
- Anemometer
- Infrared thermometer
Correct answer: Digital manometer
A digital manometer (pressure gauge) measures the pascals of pressure difference between the combustion appliance zone and outdoors during worst-case conditions.
Question 7: A gas range without a vented hood is considered what type of combustion appliance under BPI protocols?
- Sealed combustion appliance
- Unvented combustion appliance (Correct answer)
- Naturally drafted appliance
- Power-vented appliance
Correct answer: Unvented combustion appliance
A gas range vents combustion products directly into the kitchen, making it an unvented appliance that contributes to indoor air quality concerns.
BPI Combustion Safety 2
What is the primary purpose of a spillage test during a combustion safety evaluation?