InspiralR & Floval: Indoor Pre-Insulated Round and Flat Oval Solutions

Give your round and flat oval ductwork the increased performance with Thermaduct’s Inspiral R and Floval Duct Systems. These patented systems provide the increased air distribution efficiency of round or flat oval ductwork packaged in a light weight and high quality closed cell phenolic insulation. There’s no need to insulate separately as all ductwork reaches an R-6 insulated value. InspiralR is a great option for pre-insulated branch runs as well!

Round Phenolic Pre-Insulated Ductwork

Thermaduct's InspiralR Round Phenolic System


  • Patented Systems
  • Easy to Install Flanged Connections
  • Kingspan KoolDuct Aluminum Interior
  • UL 181 Listed with Incredible Fire and Smoke Performance
  • Lightweight - Up to 75% Lighter than Metal
  • Passes the UL 181 Mold Growth Test
  • Made with Pre-insulated R6 Kingspan KoolDuct Panels
  • Low Air Leakage
  • Lining options available for special applications
Thermaduct indoor round ductwork

Compare InspiralR to Doublewall Metal Ductwork to See if Your Current Duct Might Be Weighing You Down

Lightweight and easy to install, InspiralR and Floval can drastically reduce the weight of installed spiral and flat oval by up to 75%. Because it is pre-insulated, there is no need to insulate separately.

With less weight hanging above heads, engineers and building owners can rest easy as their installation safety concerns can be addressed with InspiralR and Floval.

InspiralR Round Spiral Duct Alternative

Paintable Exterior Surface - easily Blend In to your exposed applications

For exposed applications, InspiralR and Floval have an exterior surface that can easily accept water based paints. This can allow your application to achieve a specific aesthetic look without the need of any special treatments. InspiralR and Floval offer a clean, even look without the need for additional insulation wrapping that can often give traditional insulated duct an uneven or lumpy exterior.

With the lower leakage rates and R-6 Kingspan KoolDuct insualted values offered by these high efficiency systems, dust accumulation will be prevented from having streaks caused by air leaking out or condensation dripping down the ductwork.

InspiralR & Floval are engineered to perform and can be customized to match your application. The only difference you'll notice is with your utility bills!

Installing Pre-Insulated Round and Flat Oval

We designed our round and flat oval duct systems to be familiar to contractors. Standard spiral flanged connections allow InspiralR and Floval connect fast and easy.

These flanges can come in a variety of materials and finishes including galvanized (standard), aluminum, stainless steel or powder coated galvanized.

InspiralR & Floval Project Case Studies

Below are highlighted applications from our Family of Product Case Studies

Exposed Office Application

In late 2023 and into 2024, a four story office application utilized our InspiralR and Floval pre-insulated duct systems for their exposed ductwork needs.

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Missouri Industrial Facility

To meet the weight restrictions on their metal building, this industrial facility turned to lightweight phenolic ductwork to reduce building loads.

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Ohio School Cafeteria Renovation

With the exposed nature of the system, the paintable InspiralR aluminum exterior was utilized to closely blend into the school's new open cafeteria.

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Near Zero Air Leakage

Energy Efficient Air Distribution

Pre-Insulated System

InspiralR and Floval are made with R-6 Kingspan KoolDuct panels

Ease of Installation

With less weight, you can install more duct per day.

10 Year Limited Warranty

Thermaduct's InspiralR and Floval are backed by a 10 year limited warranty

See Thermaduct's InspiralR & Floval in Action

Lightweight Double Wall Spiral Ductwork InspiralR

Lightweight InspiralR Pre-Insulated Round Ductwork

Round and Flat Oval KoolDuct by Thermaduct

Insulated Spiral and Flat Oval Duct

Painted Insulated Ductwork

Low Carbon Duct System

Insulated Round Ductwork

Exposed Insulated Duct

Thermaduct InspiralR Phenolic Duct

Phenolic Pre-Insulated Ductwork

Round Kingspan KoolDuct Phenolic Ductwork

InspiralR Round Phenolic Ductwork

InspiralR Pre-Insulated Duct System

Round Phenolic Ductwork

Round Phenolic Duct Systems

Thermaduct InspiralR Doublewall Alternative

Installing InspiralR Pre-Insulated Round Duct

Installing InspiralR Pre-Insulated Round Duct

Manufactured Phenolic Ductwork

InspiralR Pre-Insulated Double Wall Spiral Alternative

InspiralR and Floval Ductwork

Lightweight Flat Oval Ductwork

Phenolic Duct

InspiralR and Floval Ductwork

preinsulated spiral ductwork

InspiralR Foodgrade Phenolic Spiral Ductwork

Pre-Insulated Spiral Ductwork System Indoor Commercial Industrial

InspiralR foodgrade pre-insulated spiral duct installation

Pre-Insulated Spiral Ductwork InspiralR

InspiralR Food Grade Double Wall Spiral Duct

InspiralR and Floval Pre-Insulated Phenolic Ductwork

Both our round and flat oval systems use an aluminum Kingspan KoolDuct interior for a high quality, fiber free insulation. Because of this, InspiralR and Floval are great for almost any indoor application.

Hospitals and Healthcare Environments

Schools and Universities

Hotels and Multifamily Structures

Commercial and Industrial Applications

Pools and Natatoriums

Phenolic Duct Installation

See How Thermaduct Products Install in the Field

While our products will feel very familiar to traditional ductwork, we have a brief online training course to cover the differences that should be observed when installing an indoor phenolic duct system.

View InspiralR & Floval Course

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Thermaduct Product Information

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