Pressure loss is one of the quickest ways to undo the investment in a good HVAC unit. You can specify the most efficient fan on the market, but if the ductwork carrying that air is fighting it every step of the way, you'll pay for it in energy bills, noise, and underperforming airflow. Most pressure loss comes down to a handful of avoidable issues in duct choice, routing, and installation, and there's a good deal you can control before problems ever show up.
What Causes Pressure Loss in HVAC Systems?
Pressure loss happens wherever air meets resistance on its way through the system. The usual culprits are:
- Tight or sharp bends that force air to change direction abruptly instead of curving smoothly.
- Sagging or crushed ducting, which narrows the internal diameter and creates turbulence.
- Rough internal surfaces, which increase friction between the airflow and the duct wall.
- Poor joints and connections, which leak air and disrupt smooth flow at every junction.
- Undersized ductwork, which forces air through a smaller cross-section than the system was designed for.
Any one of these on its own might be a minor inefficiency. Stack a few together across a run, and you've got a ventilation system working far harder than it should be.
Does Duct Material Affect Pressure Loss?
Flexible ducting is prone to sagging and kinking once it's fitted, especially over longer runs or where it isn't perfectly supported — and every sag or kink is loss in pressure waiting to happen. Rigid metal ducting avoids that problem, but only if it's installed with genuine precision, since any misalignment at the joints creates its own turbulence.
Semi-rigid ducting sits between the two. It holds its shape without sagging like flex duct, but it's flexible enough to be routed around obstacles without the joint-heavy precision that rigid duct demands. Fewer joints and a duct that stays where you put it both mean fewer opportunities for pressure loss to creep in over the life of the system.
Get the Bend Radius Right
Bends are unavoidable in most installs, but how you handle them matters. A tight, sharp bend creates far more resistance than a gradual curve of the same overall direction change.
Ducting with a smaller minimum bend radius gives you more flexibility to route smooth curves through tight spaces without resorting to the kind of harsh angle that spikes pressure loss. This is one of the reasons semi-rigid products are built with a compact bending radius — smooth routing shouldn't mean compromising on duct integrity. View our range of semi-rigid ducting.
Don't Overlook Installation Quality
Even the best duct on paper will underperform if it's fitted badly. Supports spaced too far apart let ducting sag between fixings. Loose or poorly sealed joints leak air pressure before it even reaches the room. And any kind of crushing or flattening during transport or fitting narrows the airway exactly where you don't want it narrowed. A duct that resists sagging and crushing by design takes some of that risk out of installers' hands.
Talk to Us
If pressure loss is showing up in your commissioning figures or perhaps you're tracing higher energy bills back to your ventilation system, the ducting is worth a closer look. Get in touch with the Elephant Duct team to talk through which of our semi-rigid solutions fits your next installation.
