HVAC Double Wall Spiral 

ZEN Industries' complete line of double-wall spiral and fittings.

Each piece is fabricated with an inner metal liner surrounded by insulation and covered
by a solid metal outer shell.  All of ZEN Industries' spiral double wall and fittings meet or exceed 3rd Edition 2005 SMACNA standards.

Spiral Double Wall HVAC available with:

  • 1", 2", or 3" insulation
  • Galvanized steel
  • Stainless steel
  • Galvanneal (paint grip)
  • Aluminum
  • PCD (Polyvinyl Coated Ductwork)

Concentricity of liner to outer shell is maintained by mechanical means on all fittings and pipe with more than 1" of insulation.

  • The inner liner is available in either perforated or solid metal
  • Perforations are 3/32 inch diameter with an overall open area of 23%
  • Inner liners are 24gauge for 3" thru 36" round and 22 gauge for 38" thru 58" round

The sheet metal liner protects the insulation from airflow while it stops fiberglass erosion. The insulation in our double wall spiral and fittings has both acoustical and thermal benefits. It can reduce radiated noise by 25 dB or more, compared to fiberglass duct board. ZEN's 1-inch insulation has a thermal conductance of 0.27 Btu/hr x sq. ft. x degree Fahrenheit.

Double wall spiral available with insulation thicknesses of 2-inches (0.13 Btu/hr xsq. ft. x degree Fahrenheit) and 3-inches (0.09 Btu/hr x sq. ft. x degree F).

Dual-wall pipe and fittings are joined by slip connectors and fitting collars.
The inner liner connectors are extended to mate the inner liners before the
outer shells are mated.

Double Wall Spiral for Medium Pressure Systems

Duct Gauges

  • 5" to 14" - 26 gauge spiral outer shell
  • 15" to 26" - 24 gauge spiral outer shell
  • 27" to 36" - 22 gauge spiral outer shell
  • 38" to 50" - 20 gauge spiral outer shell
  • 52" to 60" - 18 gauge spiral outer shell
  • 3" to 36" - 24 gauge perforated spiral inner liner
  • 38" to 58" - 22 gauge perforated spiral inner liner

Fittings Gauges

  • 5" to 12" - 26 gauge outer shell
  • 13" to 18" - 24 gauge outer shell
  • 19" to 26" - 22 gauge outer shell
  • 27" to 50" - 20 gauge outer shell
  • 52" to 60" - 18 gauge outer shell
  • 3" to 36" - 24 gauge perforated or solid inner liner
  • 38" to 58" - 22 gauge perforated or solid inner liner

To learn more, please Contact ZEN Industries, Inc. today. 

A Full Service HVAC Supplier

In addition to  Double Wall Spiral, learn about ZEN's Spiral Ductwork, Rectangular Ductwork, PCD Ductwork, and Specialty Ductwork

Service Area

ZEN Industries Inc. provides quality HVAC ductwork products, including rectangular and spiral duct to contractors nationwide. Located in Cleveland, Ohio, ZEN's Lean manufacturing and robust production have built a broad customer base across the US.

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