Thermaflex® PHD

Flexible Air Duct

Patent pending Thermaflex PHD flexible air duct is energy efficient, environmentally friendly and cost effective. Made with 100% recyclable inner core and vapor barrier, PHD is a great choice for LEED projects and applications where sustainability is key. The non-metallic construction of this versatile duct also makes it ideal for MRI and clean rooms.


Watch the Thermaflex PHD video .

PHD Specs

Diameter 4-12 inches ID
Pressure Rating (WG)
Positive 10 inches (4˝-12˝ ID)
Negative 1/2 inch (4˝-12˝ ID)
Velocity 5000 FPM
Temp. Range -20°F – 250°F cont.
R-Value R-8.0 = 2.25″, .74 lb./ft3 minimum density fiberglass blanket.


This product can expose you to chemicals including Antimony Trioxide, which is known to the State of California to cause cancer. For more information go to