Frequently Asked Questions

How are Thermaduct products different than what I use now?

Thermaduct products are fully engineered high R-value, low air leakage pre-insulated duct solutions that offer high efficiency air distribution. Each duct system has a fiber free insulation core for increased indoor air quality. Air passes through a smooth aluminum interior, free from fibers that are found in duct liners. Because our products are pre-manufactured, your customer is assured the highest performance and energy savings available.

How is installing a Thermaduct product different than Sheet Metal?

While we try to keep our products familiar to HVAC contractors, there are some differences in using our phenolic products that should be observed. Support practices, connections and field modification all may differ in order to set the foundation for a long lasting, weather resistant application.

Online training is available for installers that covers the guidelines discussed in our installation manual. Contractors installing a Thermaduct product should talk to their local Thermaduct representative or request access directly on our training site.

Is Thermaduct your company or product?

Our Rectangular Outdoor Ductwork, Thermaduct, was our first pre-insulated solution we introduced in 2011 and bears our company name. We have gone on to develop round and flat oval solutions for both indoor and outdoor applications since then and have introduced them into the Thermaduct family of products.

What insulation R values can your products provide?

Our rectangular outdoor pre-insulated ductwork, Thermaduct, can provide R8 through R-24 insulated values. Thermaround comes standard at an R-12 insulated value. For indoor applications, both InspiralR and Floval made with R-6 phenolic panels.


Is cladding applied in the field with your outdoor products?

No, we do not require cladding to be applied in the field. Our vinyl cladding on Thermaduct and Thermaround is factory laminated onto the panel before fabrication and does not require any cladding to be applied in the field.

This is because other pre-insulated duct systems may rely on cladding tapes which can experience degradation over time and may be prone to misapplication.

What are the lead times on ordering a Thermaduct product?

Thermaduct products are fabricated in licensed facilities across the country through trained fabrication partners. Lead times may vary from location to location, but standard lead times are usually 2-4 weeks from issuance of a PO and verified field measurements.

Are Thermaduct products easy to install?

HVAC Contractors should feel right at home installing Thermaduct products. Please review our Installation Resources Page for an overview of our systems installation steps. You can also receive a Contractor’s Installation Manual from any Thermaduct Representative.

Where can I buy Thermaduct products?

We have a network of partners in all major market areas across the United States. Locate your Representative here. If you do not see one in your area, please contact Thermaduct at 855-809-6903.

Can Thermaduct products be painted?

Vinyl cladded Thermaduct & Thermaround are not paintable. The three vinyl color options are specifically chosen and tested to ensure minimal heat absorption & buildup to maintain surface temperatures below expansion of vinyl. Paints can damage the cladding and would void Thermaduct’s 10 Year limited warranty.

For applications that require a specific architectural look, we would recommend our Metal Clad line of products that can offer 24 Kynar coated colors or paint grip galvanized metal.

Will Thermaduct products comply with the SMACNA Phenolic Duct Construction Standards?

Thermaduct rectangular products will meet or exceed the SMACNA Phenolic Duct Construction Standards, which are internationally recognized by the leading authority in HVAC construction. These do not currently apply to round or flat oval ductwork, but the same attention to product safety and longevity will be adhered to in all Thermaduct offerings.

Can your outdoor products be used indoors?

Thermaduct and Thermaround are designed to withstand the outdoor elements with unmatched quality and durability. For indoor applications, factory made air ducts must have the UL 181 listing, which does not extend to our vinyl cladded products. Both InspiralR and Floval are UL 181 listed products and are excellent solutions for indoor applications.

Where is Thermaduct Manufactured?

Thermaduct is headquartered in Perrysburg, Ohio.

Is there any required training to install Thermaduct products?

Thermaduct, Thermaround, InspiralR and Floval are designed to be familiar to HVAC Contractors. Despite this, we do require online training for installations to cover the differences in installing a phenolic system compared to traditional metal ductwork. Our installation instructions in our online courses respect your time and contain all documents in one place. You can request access today by visiting

What type of foam is Thermaduct using?

Thermaduct, Thermaround, InspiralR and Floval all use a high quality Kingspan KoolDuct core, which is certified to have greater than 90% closed cell content. This means a low potential of water intrusion and the highest R-value per inch.

Other pre-insulated manufacturers make claims of high closed cell content, but require up to 30% more insulation to reach the same R-value. This may be prone to more water intrusion should cladding issues arise.

What Static Pressure can Thermaduct products handle?

Thermaduct products all have a high static pressure design. Proper reinforcement will be required.

Thermaduct - 10" w.c. Positive, 10" w.c. Negative

Thermaround - 10" w.c. Positive, 8" w.c. Negative

InspiralR - 10" w.c. Positive, 8" w.c. Negative

Floval - 10" w.c. Positive, 8" w.c. Negative

How do you accommodate dynamic load with your outdoor products?

Outdoor applications require additional considerations that may not be experienced in the indoors. Wind, rain and snow all need to be planned for. This is important with pre-insulated ductwork where snow doesn’t melt from escaping heat that may occur in a sheet metal installation that is not well insulated.

Thermaduct uses a patented reinforcement system called Airtruss to go above and beyond the SMACNA Phenolic Duct Construction Standards. Snow load calculations for each region across the country are considered in the design of our outdoor products. This system is built in, flange to flange, and gives our product a backbone that other pre-insulated duct systems do not have.

Why are your outdoor products white?

The standard color of our outdoor products is white to comply with Cool Roof Initiatives across the country. At peak temperatures a white roof is 20 degrees cooler than a roof with an aluminum coating, and up to 60 degrees cooler than a dark roof. This is important with ductwork as the temperature differences between your airstream and outdoor environment may be drastically different.

For installations where color may be important, our rectangular outdoor duct does have a tan and light gray color to match common building facades or with our Thermaround system, we offer a Kynar Finished Metal cladded system for architectural applications.

How are the seams of Thermaduct and Thermaround made?

While other manufacturers use tapes, adhesives and seams held together with screws, which experience degradation over time, our outdoor products use a patented heat or solvent welded seam to ensure impervious water and air integrity.

How do Thermaduct and Thermaround perform in warmer climates? Cooler climates?

Our outdoor products have a UV stable, 1000 micron vinyl cladding and are designed to handle any climate.

Do InspiralR and Floval come in other colors?

While Thermaduct and Thermaround’s cladding color has been carefully selected and is not paintable, both InspiralR and Floval can be painted in indoor exposed applications. These paints should be water based and compatible with aluminum surfaces.

Consult your application’s engineer when painting InspiralR and Floval as paint selections do have a bearing on fire performance requirements.

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