10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
These 10 free MFBO questions are organized by exam domain, so you can see how each part of the Multifamily Building Operator blueprint is tested. Reveal the answer and explanation under each question.
On calm winter days, drafts enter a 12-story building at the lobby while air leaks outward near the roof. This pattern persists with elevators idle and ventilation fans at constant settings, then weakens as outdoor temperatures approach indoor temperatures. What drives this floor-to-floor pattern?
Correct answer: A - Buoyancy-driven stack effect through vertically connected spaces.
An insulation proposal for a wood-framed wall must deliver an effective whole-wall R-value of at least R-18. Its simplified parallel-path model assigns R-24 to 75% of the wall area and R-8 to the remaining 25%; each resistance includes all layers in that path. What belongs in the technical review?
Correct answer: A - R-16; the proposal fails the whole-wall requirement.
Both windows in a bedroom are dry between the panes, but water forms on the room-side metal frames during cold, rain-free nights. Indoor air is 72°F with a dew point of 51°F; the wet frames measure 44°F. The resident asks whether the insulated-glass seals have failed. Which explanation fits the location and measurements?
Correct answer: A - Surface condensation: the frame is colder than the adjacent air's dew point.
An owner credits a control retrofit for lowering gas use. Two 30-day periods had the same occupancy and hot-water demand: before, 1,400 therms and 600 heating degree-days; after, 1,100 therms and 400 heating degree-days. Nonheating use was 200 therms in each period, and both degree-day totals use the same base temperature. Based on space-heating fuel per degree-day, how should the operator assess the claimed improvement?
Correct answer: D - Heating fuel intensity rose 12.5%; the totals do not demonstrate improved heating performance.
LED upgrades reduce common-area electricity use from 24,000 to 18,000 kWh in comparable billing periods. Billed demand remains 90 kW, set by a 15-minute period when several discretionary large motors operate together. The tariff charges the month's highest 15-minute average at the same demand rate regardless of day or time, with no ratchet. Which operating change directly targets the charge that did not fall?
Correct answer: B - Stagger the operating schedules of the discretionary large motors.
A resident partly closes the hand valve on a one-pipe steam radiator to reduce heat. The radiator then begins knocking and heating unevenly. It slopes toward the supply connection, its air vent operates, and nearby radiators heat normally. Which correction addresses the new symptom at its source?
Correct answer: C - Fully open the supply valve and verify drainage toward that connection.
A bathroom exhaust grille measures 22 CFM with the bathroom door shut and 61 CFM with it open. The specified minimum is 50 CFM with the door shut. The fan, damper, and grille are unobstructed; a renovation replaced the former door undercut with a tight threshold seal. Where should the corrective work be directed?
Correct answer: D - Restore an approved transfer-air path and remeasure the closed-door flow.
After a shower valve repair, water checks show 146°F at storage, 128°F in the hot-water return, and 112°F at other mixed outlets. The repaired shower delivers 134°F. The approved water-management plan calls for storage above 140°F, circulation above 120°F, and mixed shower delivery no higher than 120°F. Select the response that controls the identified hazard without defeating the other temperature controls.
Correct answer: C - Isolate the affected shower; have its mixing control corrected and the outlet retested.
A replacement laundry dryer is a listed ventless heat-pump model approved for that location. Its electrical connection, clearances, condensate drain, and manufacturer-required checks have passed. The operator's final observation is that no duct carries dryer exhaust outdoors. How should this finding affect handover?
Correct answer: B - It does not prevent handover; document the model's filter and condensate maintenance.
During a boiler-room inspection, a properly checked ambient carbon monoxide monitor climbs to 84 ppm. A nearby resident reports headache and dizziness. What takes priority before any further equipment testing?
Correct answer: B - Leave while alerting occupants to evacuate, then call emergency services from outside.
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