CBD Ventilation & Mechanical Systems 2 — Questions and Answers
Question 1: A continuous ventilation strategy for a bathroom, per ASHRAE 62.2, requires a minimum exhaust rate of:
- 10 CFM
- 20 CFM (Correct answer)
- 35 CFM
- 50 CFM
Correct answer: 20 CFM
ASHRAE 62.2 allows continuous bathroom ventilation at a reduced rate of 20 CFM, which is lower than the 50 CFM required for intermittent operation.
Question 2: Which type of radiant floor heating system circulates heated water through tubing embedded in or beneath the floor?
- Electric resistance heating
- Hydronic radiant heating (Correct answer)
- Infrared panel heating
- Forced-air radiant heating
Correct answer: Hydronic radiant heating
Hydronic radiant heating uses a boiler or water heater to circulate hot water through PEX or similar tubing beneath the floor, providing efficient, even heat.
Question 3: When installing electric radiant floor heating beneath tile in a bathroom, the thermostat sensor probe should be placed:
- On top of the heating mat before tile installation
- Between the heating cables in the mortar bed (Correct answer)
- At the perimeter wall near the floor
- Above the ceiling directly over the heated area
Correct answer: Between the heating cables in the mortar bed
The sensor probe must be embedded between heating cables in the mortar bed so it accurately reads floor temperature and prevents overheating.
Question 4: An Energy Recovery Ventilator (ERV) in a bathroom ventilation system offers which primary advantage over a standard exhaust fan?
- Higher CFM output per watt
- Transfers heat and moisture from exhaust air to incoming fresh air (Correct answer)
- Completely eliminates the need for ductwork
- Automatically adjusts to barometric pressure changes
Correct answer: Transfers heat and moisture from exhaust air to incoming fresh air
An ERV recovers both heat and moisture from outgoing stale air and transfers them to incoming fresh air, improving energy efficiency in climates where humidity balance is important.
Question 5: Backdrafting of combustion appliances near a bathroom can occur when a powerful exhaust fan:
- Runs at too low a CFM setting
- Creates negative pressure that reverses combustion gas flow (Correct answer)
- Overheats and trips its thermal cutout
- Operates on a humidity sensor in a sealed bathroom
Correct answer: Creates negative pressure that reverses combustion gas flow
High-capacity exhaust fans can depressurize a home, causing combustion appliances to backdraft and pull flue gases back into the living space.
Question 6: The National Electrical Code (NEC) requires GFCI protection for all 15- and 20-ampere receptacles in bathrooms within what distance of a sink?
- Within 3 feet only
- Within 6 feet only
- All bathroom receptacles regardless of distance (Correct answer)
- Only receptacles directly above the sink
Correct answer: All bathroom receptacles regardless of distance
The NEC requires GFCI protection for all 15- and 20-ampere receptacles installed in bathrooms, regardless of their distance from a water source.
Question 7: Which exhaust fan installation location is most effective for capturing steam and moisture in a bathroom containing a separate shower and soaking tub?
- Centered on the ceiling between both fixtures
- Directly over the toilet only
- As close to the shower as ceiling framing allows (Correct answer)
- At the bathroom door to exhaust air before it spreads
Correct answer: As close to the shower as ceiling framing allows
Placing the exhaust fan close to the primary steam source—the shower—captures moisture most efficiently before it disperses throughout the room.
CBD Ventilation & Mechanical Systems 2
A continuous ventilation strategy for a bathroom, per ASHRAE 62.2, requires a minimum exhaust rate of: