Aluminum foil ducts are widely used in HVAC systems for their flexibility, lightweight nature, and resistance to corrosion. However, there are variations in their design and construction, notably between standard aluminum foil ducts and semi-rigid aluminum foil ducts.
What is Aluminum Foil Duct
Made of flexible aluminum foil, this is the most common type for dryer transition ducts — those that connect from the appliance to the main duct that runs to the outdoors. Foil duct can accordion from about 1 to 8 feet, which is usually enough for most installations. Double-check to make sure that this type is approved for your dryer and allowed by local code. Transition ducts must not be concealed inside walls or other building cavities and usually have a maximum allowed length of 8 feet. Foil duct is held in place with dryer clamps or large hose clamps. Metal tape can be used, too, but clamps make it easier to remove the tubing for cleaning.
What is Semi-Rigid Metal Duct
Semi-rigid metal (usually aluminum) duct is flexible and similar to foil ducting but quite a bit more rigid. Like foil duct, semi-rigid is used only for transition ducting and should not be concealed in walls or floors. It is typically installed with clamps. Although semi-rigid metal duct is often stronger and has a smoother interior (catches less lint) than foil duct, it is more common to find listed foil duct than listed semi-rigid.
Performance comparison
Table 1: Performance Comparison
| Aspect | Aluminum Foil Duct | Semi-Rigid Aluminum Foil Duct |
|---|---|---|
| Insulation | No inherent insulation; additional wrapping required | Built-in insulation reduces heat loss/gain |
| Durability | Less durable, prone to punctures and tears | More durable due to layered construction |
| Airflow Efficiency | Good, but can be reduced by bends or kinks | Excellent, maintains shape better |
| Condensation Control | Poor; condensation can form on the inner surface | Better; insulation helps control condensation |
| Noise Reduction | Minimal noise reduction | Reduces noise transmission through insulation |
Applications
- Aluminum Foil Duct:
- Used in areas where space is limited or where flexibility is key, like connecting HVAC units to vents in residential or commercial buildings.
- Suitable for short runs or where the duct needs to navigate through tight spaces.
- Semi-Rigid Aluminum Foil Duct:
- Ideal for longer runs or where maintaining insulation is crucial, such as in commercial buildings, industrial settings, or for outdoor applications where temperature control is necessary.
- Often used in environments where noise reduction is beneficial, like in hospitals or office buildings.