Some builders have no choice but to install HVAC ducting on the rooftop of a building. This is particularly true for buildings where the external units of the HVAC system can only be placed on the rooftop due to space constraints. This article discusses why spiral ducts are better than rectangular ducts for rooftop installations.

The Impact of Rain

Raindrops can easily roll off a spiral duct when compared to rectangular ducts. This is because the smooth surface of spiral ducts makes the water roll down due to the action of gravity. Rectangular ducts provide a flat surface that reduces how quickly the water can flow off the ducts. Consequently, you may need to spend more money sealing the joints on rectangular ducting so that water does not penetrate the ducts through poorly sealed joints or seams.

The Impact of Snow

Snow is more likely to accumulate on the flat surface of rectangular ducting when compared to the round surface of spiral ducting. That accumulated snow can cause the ducts to collapse inwards, blocking the flow of air within the system. It is therefore better for you to install spiral ducts so that most of the snow that drops on them slides off without causing any major damage.

Heat Loss or Heat Gain Differences

Rectangular ducting has sharp corners/edges that create resistance to the flow of air through the system. This can slow down how quickly the conditioned air can flow into your house. That slow pace creates an opportunity for the ambient temperature to have a greater impact on the conditioned air in case the ducts were poorly insulated. For example, the cool air will be more likely to gain heat from the ambient air of the rooftop where the ducts are located. This heat gain or heat loss can lower the effectiveness of the entire HVAC system. Spiral ducts do not have sharp edges or sharp corners within them. Consequently, air will quickly flow into your house without being affected significantly by the ambient conditions on the roof.

As you can see, the shortcomings of rectangular ducting can make you to incur higher costs to buy more materials, such as anchors to support the ducts against the force of the wind. The use of more materials may result in higher installation costs since the contractor is likely to spend more time working on your building. It is therefore better for you to use spiral ducting for rooftops so that you can avoid some of those added costs. For more information, contact companies like Trans Vent Spiral Tubing.