In the context of heating and cooling systems, laminar flow describes the smooth, unhindered passage of air through duct work. The opposite of laminar flow is turbulent flow, where the air tumbles around, getting caught in pockets, churning chaotically in vortices and doing a poor job of circulating. When air flows through the system smoothly, energy is conserved, whereas when the air flows turbulently, friction increases, momentum is lost and energy is wasted.
Rigid ducts have seen a resurgence over flexible duct work, because it turns out that rigid ducts tend to favor laminar flow in a number of ways. One factor is the smoothness and straightness of rigid ducts. The interior surface of flexible ducts tends to be rougher and prone to pinching or kinks that stir up the air and introduce turbulence, friction and dynamic losses. Another factor is the resilience and air-tightness of rigid ducts. Being harder and less susceptible to damage and wear, rigid ducts tend to keep their air seal as tight as possible, so that when insulation is wrapped around the exterior of the ducts, fibers are less likely to enter the ducts.
Duct outlets and registers should be cleaned as part of your regular home cleaning routine. It’s the filters in the system — and to a lesser degree the grilles and registers at the duct outlets — that collect most of the dust, and therefore need changing or cleaning. The ducts themselves usually don’t require cleaning, especially if filters are kept clean, however, if you find the insides of ducts do need cleaning, we at Comfort Control provide this service. As part of an overall assessment of the energy efficiency of your system, we can determine whether your ducts favor laminar flow or tend to produce turbulent flow. If you would benefit from new duct work, we can plan and install it for you.