Spiral Vs Rectangular Ductwork: How Their Designs Differ

Ductwork can be found in all kinds of buildings, but primarily in commercial premises such as factories, offices and shops. It is used in heating and ventilation (HVAC) systems to move air around, whether that is bringing in heated or air-conditioned air or extracting stale air and fumes. But all ducts are not the same: they come in different shapes and different materials.

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Types of Duct

Ducting generally comes in two types. Rectangular ducts use more metal and therefore have a higher capital cost. They are mostly used because they can be adapted to any building and are easy to fabricate for trunk and branch designs.

Spiral ducts, on the other hand, useless metal and are lighter and easier to transport and install. Lengths can easily be connected using overlapping joints secured with clamps.

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Pros and Cons

Spiral ducts are less prone to leaks, and that leads to a more efficient system and less energy needed to drive the fans. A spiral duct from a supplier such as https://www.dustspares.co.uk/ductwork-parts/galvanised-steel-spiral-duct.html is also generally quieter in operation. This is because it has better pressure drop characteristics compared to rectangular ducts, which means lower fan speeds are needed. This, in turn, means there’s less chance of vibration being transmitted along with the ducting.

If you need to add insulation to your ducting, it’s easier to do so with spiral ducts because the insulation can be added on the outside. Rectangular ducting needs to be insulated inside, which can be more complex.

If there’s plenty of room for installation, then spiral ducts are generally preferred as they are easier to install and adapt to a given situation. They can be hidden above suspended ceilings or left exposed as an architectural feature. Rectangular ducts, on the other hand, can be more easily adapted to tight spaces but are more expensive and complex to install.

There are a number of factors to consider when specifying ductwork. These include the size and design of the building, how it will be used and where it’s located. Cost is a factor as well of course, and since spiral ducts use less material they are generally cheaper. They can be supplied in standard lengths too, so you may be able to buy most of your installation needs ‘off the shelf’.