A replacement gas water heater must obtain its combustion air from outdoors rather than from the room where it is installed. Which venting configuration is designed to provide that outside-air intake and discharge combustion products outdoors?
- ANatural draft
- BPower vent
- Direct vent
- DIndirect vent
Where to look it up
https://www.hotwater.com/info-center/water-heater-venting.html
Why C is correct
A direct-vent configuration takes combustion air from outside and sends exhaust outside. A power-vent exhaust fan alone does not establish that combustion air comes from outdoors; power-direct-vent systems combine outside-air intake with powered venting. Select a listed appliance and follow its model-specific intake, exhaust and clearance requirements. The condition here is the source of combustion air, not simply whether the exhaust has a fan. Source: https://www.hotwater.com/info-center/water-heater-venting.html