air supply inlet jargon

Glevin

What is the difference between nonmechanical and mechanical air supply?
I am investigating purchasing a tankless water heater. When deciding location, horizontal vent location appears to be a big issue.

The distance between the "HVAC air supply inlet" and the "water heaters concentric, combustion air inlet" differs between mechanical and nonmechanical air supply inlet systems.

My HVAC unit is in the basement. I have a duct (?fresh air?) going from outside to the return plenum before the filter. Would this be considered a nonmechanical air supply inlet?

Thank you.

hvac benny

Since the intake is connected to the furnace ducting, the fan's operation will draw the air in. Therfore, it is a mechanical inlet.

beenthere

Yep, benny's right, its considered a mechanical ventilation.

Subcooled

Non mechanical = Passive
Mechanical = Powered