How Far a Dryer Vent Must Be From Windows, Doors and the AC Unit

Why the Hood Location Matters

A dryer hood breathes out warm, damp air with fine lint in it for as long as the dryer runs. Put that hood under a bedroom window and the damp air comes back inside when the window is open. Put it beside a soffit vent and it is drawn into the attic. Point it at the outdoor AC unit and the lint goes where the air goes.

The code answers most of this with a few distances. The rest is common sense about what sits in front of the hood.

The Dryer Rule of 3 Feet in Any Direction

The 2023 Florida Building Code, Residential, section M1502.3 says that where the dryer manufacturer's instructions do not give a termination location, the exhaust duct must end not less than 3 feet in any direction from openings into buildings, including openings in ventilated soffits. The same section requires a backdraft damper and forbids a screen.

In any direction means above, below and to the side. A hood 3 feet to the left of a window but directly below its sill does not pass if the sill sits within 3 feet. Measure from the edge of the hood's opening to the nearest edge of the window, door or vent opening.

• Operable windows: 3 feet in any direction.
• Fixed windows and doors: counted as openings into the building.
• Ventilated soffit openings: 3 feet, named in section M1502.3 itself.
• Property line: 3 feet, under the general exhaust rule.
• Mechanical air intakes: 10 feet, unless the hood is 3 feet above the intake.

The General Exhaust Rule for Openings, Property Lines and Air Intakes

Section M1501.1 sends the air from every mechanical exhaust system outdoors in accordance with section M1506.3. That section asks exhaust openings to end at least 3 feet from property lines, at least 3 feet from operable and nonoperable openings into the building, and at least 10 feet from mechanical air intakes, except where the exhaust opening is 3 feet above the intake.

A mechanical air intake is an opening that draws outside air into the house's systems, such as a fresh-air intake for ventilation. Where a house has one, the dryer hood keeps 10 feet away from it or sits 3 feet above it. On a narrow side yard, the 3 feet from the property line can decide which wall the hood goes on.

The AC Unit Is Not Named in the Code but Still Gets in the Way

No section of the dryer code names the outdoor air conditioning unit. Dryer makers cover it anyway. Whirlpool's instructions say the exhaust hood must be at least 12 inches from the ground or any object that may be in the path of the exhaust, and GE's ask for 12 inches between the hood and the ground or any other obstruction. A condenser parked in front of the hood is exactly that kind of object.

There is a practical reason too. The outdoor unit pulls outside air through the fins of its coil, and lint in that air ends up on the fins. A hood that blows at the condenser feeds it lint every laundry day. The fix is placement: put the hood on a wall section where its stream of air has open space in front of it, well clear of the unit.

Measuring Your Hood With a Tape

With a tape measure you can check your hood in a few minutes. Measure from the hood's opening to the nearest window, door and soffit vent, in every direction. Note whether the AC unit or anything else sits within 12 inches of the hood's outlet, and whether the hood is at least 12 inches off the ground; our guide on dryer vent height off the ground covers that rule.

Check your dryer's installation instructions as well. Where the maker gives its own termination location, section M1502.3 defers to it.

When the Hood Is in the Wrong Place

A hood too close to a window or blowing at the condenser cannot be fixed by cleaning. The duct has to end somewhere else, which means a new wall opening, a short extension or a different route, and closing the old opening. That is dryer vent installation work, and it starts with measuring the alternatives.

Hood placement is measured on site by our experienced technicians, part of a local family business that is Proudly American. On a free inspection we set a tape against your hood, the code and the dryer's instructions, then put any change in a written estimate. When the hood is fine where it is, a Proudly American crew like ours says so plainly.