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Zero Clearance Grease Duct


What sets us apart?

Integrated centering sleeve stabilizes the tubes during assembly and covers joint grooves that might otherwise be exposed and trap grease contaminants. Also provides a channel for high temp sealant to accurately insure system water tightness. Extra large spacing between outer wall sections allows for quick and easy installation of the securing band.

  • Construction
  • Specifications
  • Features
  • Literature
  • Warranty

Grease Duct - Construction

Fire-rated (DIS3Z) significantly reducing installation footprint and frees up space for other use. No need to build an expensive fire-rated chase or apply two layers of fire wrap typically required for welded steel grease duct designs.

Available in 5"- 36"; 3" wall insulation and single wall. DuraStack Pro is now UL 1978 listed for applications where 1" air insulated, 1", 2", or 4" AES Wool Insulated grease duct is required. Please see the DuraStack Pro product pages for more details. 

UL1978, UL2221 (2 HR)
IMC, UMC and NFPA96 Code Compliance

Blanket insulation is already installed in the portion that lines up with the outside casing. We provide an insulation band to be field installed behind the outside band.

Goes together with the inner flange and inner locking band (with centering extension). The outer locking band is on the outside for more support, making it a stronger system.

DuraVent, Inc. Model DIS3Z grease ducts have been tested and listed by UL to UL/ULC Standards. UL 1978 Grease Duct and UL2221(2 hr Fire Rating). IMC, UMC and NFPA96 Code Compliance.

Grease Duct is subjected to rigorous and stringent requirements of the UL1978 & UL-2221 standard, including continuous firing at 500°F (260°C), plus 30 minute firing at 2000°F (1093°C).

Grease Duct Specs 1 Grease Duct Specs 2


  • Stainless steel construction is highly corrosion resistant and extremely durable.
  • Round tubular design maintains structural integrity significantly longer than a rectangular welded steel product.
  • 0" Clearance grease duct (3" insulation & 2 hours fire rating) eliminates the need for a separate fire-rated enclosure around the duct.
  • Inner casing available in 304 or 316 stainless steel.
  • Outer casing available in 304 or galvalume.
  • Superior flow rate is achieved with round tube construction.
  • Modular design assembles quickly with common tools.
  • Contaminants of combustion are not trapped within the flue like it is commonly found in the corners of a rectangular design, thus making it much easier to clean and reduce the chance of fire from accumulated grease.
  • No safety concerns with having welding on site that could cause a fire.
  • Backed by a comprehensive Limited Lifetime Warranty.

This DuraVent Limited Lifetime Warranty warrants your Factory-Built Grease Duct (Product) in a grease duct application to be free from defects in material and workmanship at the time of manufacture when properly connected to and included as a part of a code compliant commercial kitchen ventilation system for cooking appliances. This Limited Lifetime Warranty includes all components and fittings. After installation, if covered components manufactured by DuraVent are found to be defective in materials or workmanship during the Limited Lifetime Warranty period and while the Product remains at the site of the original installation, DuraVent will, replace the covered components. DuraVent reserves the right to replace covered components with an equivalent product and the replacement must be carried out in accordance with DuraVent recommendations. If replacement is not commercially practical, DuraVent will, at its option, refund the purchase price or wholesale price of the DuraVent Product, whichever is applicable. Labor or freight costs to remove or replace DuraVent components is not included. THERE ARE EXCLUSIONS AND LIMITATIONS to the Limited Lifetime Warranty as described herein.

Warranty coverage begins on the date of shipment from DuraVent.

This Limited Lifetime Warranty applies only if the Product is installed in the United States or Canada and only if used for the application for which it was designed and intended. The Product must be installed and maintained in accordance with the design, installation and maintenance instructions for the Product and in compliance with all applicable installation and building codes and high quality, industry accepted trade practices.

This warranty is non-transferable and extends to the original owner only. The Product must be purchased through a DuraVent Agent/Representative and proof of purchase must be provided.

Components and fittings (excludes labor) –

  • Year 1-10 – Replacement of all components and fittings.
  • Year 11-15 – Replacement at 75% off of the prevailing list price in effect at the time of replacement (25% of the retail list price paid by the consumer).
  • Year 16 + – Replacement at 50% off of the prevailing list price in effect at the time of replacement (50% of the retail list price paid by the consumer).

DuraVent will not be responsible for: (a) damages caused by normal wear and tear, corrosion from salt air, accident, riot, fire, flood, high wind or acts of God; (b) damages caused by abuse, negligence, misuse, or unauthorized alteration or repair of the Product affecting its stability or performance. (c) damage resulting from failure to reasonably clean, care for or maintain products in accordance with the printed design, installation and maintenance instructions for the Product; (d) damages caused by failing to provide proper maintenance and service in accordance with the design, installation and maintenance instructions for the Product, including damage to the finish of the Product caused by the use of improper solvents/chemicals or improper cleaning methods; (e) damages, repairs or inefficiency resulting from faulty installation or application of the Product; (e) replacement of system sealants as a result of improper installation or a system grease fire.

This Limited Lifetime Warranty covers only parts as provided herein. DuraVent’s entire liability is limited to the purchase price of this Product. In no case shall DuraVent be responsible for materials, components or construction which are not manufactured or supplied by DuraVent or for the labor necessary to install, repair or remove such materials, components or construction. All replacement or repair components will be shipped F.O.B. from the DuraVent manufacturing facility.

It is expressly agreed and understood that the sole obligation of DuraVent and the purchaser’s exclusive remedy under this warranty, under any other warranty, expressed or implied, or in contract, tort or otherwise, shall be limited to replacement, repair, or refund, as specified herein.

In no event shall DuraVent be liable for any incidental or consequential damages caused by defects in the Product, whether such damage occurs or is discovered before or after replacement or repair, and whether such damage is caused by DuraVent negligence.

DuraVent makes no expressed warranties except as stated in this Limited Lifetime Warranty. The duration of any implied warranty is limited to the duration of this expressed warranty.

No one is authorized to change this Limited Lifetime Warranty or to create for DuraVent any other obligation or liability in connection with the Product. Some states and provinces do not allow the exclusion or limitation of incidental or consequential damages, so the above limitations or exclusions may not apply to you. The provisions of this Limited Lifetime Warranty are in addition to and not a modification of or subtraction from any statutory warranties and other rights and remedies provided by law.

DuraVent reserves the right to investigate any and all claims against this Limited Lifetime Warranty and to decide, in its sole discretion, upon the method of settlement.

DuraVent shall in no event be responsible for any warranty work done by a contractor that is not approved without first obtaining DuraVent’s prior written consent.

In order for any claim under this warranty to be valid, you must contact the DuraVent Agent/Representative from which you purchased the Product. If you cannot contact the Agent/Representative, then you must notify DuraVent in writing. DuraVent must be notified of the claimed defect in writing within 90 days of the date of failure. Notices should be directed to the DuraVent Warranty Department.