In a typical American house, the ventilation system comprises various components that work together to distribute and manage air quality and temperature throughout the home. Here are the key features of typical ventilation duct systems in American homes:

1. Types of Air Ducts: There are generally two main types of air ducts in an HVAC (Heating, Ventilation, and Air Conditioning) system:

   • Supply Ducts: These ducts deliver air from the HVAC system to different rooms in the house. Supply vents, often having dampers, are used to control the airflow and are commonly referred to as registers.
   • Return Ducts: These return ducts bring air back to the HVAC system for re-conditioning and circulation.

2. Duct Materials: The most commonly used materials for ducts are sheet metal (galvanized steel or aluminum) because of their durability and effectiveness. Flexible ducts are also used in certain spaces for easier installation and cost-effectiveness.

3. Vent Placement: Vents can be located on the floors, walls, or ceilings, depending on the home's design and the room's layout. The placement is crucial for efficiency in airflow distribution.

4. Size and Design: The ducts usually have varied sizes based on their function and the dimensions of the home. For instance, supply vents might be larger to ensure enough air is distributed to larger rooms.

Here are some images illustrating typical ventilation duct setups:

Sources for these insights include articles and guides from Supertech HVAC and Thiele about duct placement, types, and materials (Source 1, Source 2).

In a typical American house, ventilation ducts are crucial for the heating, ventilation, and air conditioning (HVAC) system. These ducts are generally divided into two types: supply ducts and return ducts. Supply ducts distribute conditioned air to various rooms, while return ducts carry the air back to the HVAC unit. Here are some key points about these ducts:

1. Supply Ducts: These ducts blow warm or cool air to an area inside a home. Supply vents often have dampers to control the flow, called registers. Source

2. Return Ducts: They are responsible for drawing air from the rooms back to the HVAC unit. For a standard residential HVAC unit, you'll generally need one supply vent and one return vent for every 100 to 150 square feet. Source

3. Duct Materials: The most common type of rigid air duct material found in today's homes is sheet metal, which typically refers to either galvanized steel or aluminum metal. Source

4. Duct Sizes: Ducts from the HVAC unit out to the registers are more typically 8 or 12 inches in diameter. Source

5. Ventilation System Design: A typical supply ventilation system has a fan and duct system that introduces fresh air into usually one -- but preferably several -- rooms that residents occupy. Source

6. Number of Air Ducts: Depending on your home design, supply vents appear on the floors, walls, and ceilings in every room that requires conditioned air. Source

Here are some images that illustrate typical ventilation ducts in an American house:

These ducts are essential for maintaining comfortable indoor air quality and temperature.