MDWi Double Wall Insulated Positive Pressure Chimney System
- UL 1777, UL 103, UL 2561, and UL 1738 listed
- 1400°F continuous / 1800°F intermittent temperature rating
- Double-wall insulated construction for improved thermal efficiency. Available in 1", 2",or 4" FyreWrap Elite® insulation Blanket configurations.
- Designed for indoor and outdoor commercial applications
- Complete line of UL-approved fittings, supports, and accessories
- Available Diameters from 6" through 48”
- Material Available in mill-certified: 304, 316L, 444, AL29-4C Stainless Steel Mill-certified stainless steel construction for maximum corrosion resistance
- 100% stainless steel supports, bands, and hardware
- Lifetime Warranty
Grease Duct for commercial kitchen
Venting for commercial and Industrial Boilers.
Agriculture & Bulk Materials
Heavy Manufacturing & Foundries
Mining & Mineral Processing
Energy & Power Generation
Chemical & Pharmaceutical
Blasting & Shot Blast
Wood & Paper Mills
The MDW Series is a factory-built, Double-wall chimney and venting system designed for demanding commercial and industrial applications. Engineered to perform under negative, neutral, and up to 90” WC positive pressure positive pressure conditions, MDW delivers reliable performance across a wide range of fuel types and installation scenarios.
Industries & Applications
Category I Gas Appliances
Oil-Fired Appliances
Dual Fuel Systems
Special Gas Vent
CHP (Combined Heat & Power) Venting
Generator Exhaust
Fireplace Systems
Ideal For
Breeching systems
Chimney relining
New construction
System extensions and retrofits
Fuel Compatibility
Suitable for Category I gas, oil, dual fuel, and special gas applications.
Built to the Highest Standards
Tested and Listed to UL 1777 for Category I gas and oil-fired appliances
Tested and Listed to UL 103, UL 103 HT and UL 2561
Tested and Listed to UL 1738 Special Gas Vent Standard
Engineered for Performance
1400°F continuous temperature rating
1800°F intermittent temperature rating
2100F intermittent (10 minute) Temperature Rating
Performs under negative, neutral, and positive pressure
Available in diameters from 6″ through 48″
Premium Materials
100% stainless steel supports, hardware, and components
Mill-certified stainless steel grades available: 304, 316L, 444, and AL29-4C
MDWi models utilize high-performance FyreWrap® Elite® insulation for superior thermal protection, low thermal conductivity, and reduced clearance to combustibles in high-temperature applications.
Complete library of UL-approved fittings and accessories
Backed for Life
Lifetime Warranty
UL-listed factory-built construction
Trusted by contractors, architects, and engineering firms nationwide
Engineering & Support Included
Technical support for contractors, architects, and engineering firms
Complete design assistance, drafting, and structural calculations
Expert solutions for complex job-site challenges
Industry-leading fabrication turnaround
Rush production available for same-day installations
Dedicated support team to keep your project moving
Material
Manufactured from minimum 20-gauge (0.0359″) stainless steel for superior durability and corrosion resistance.
Available in mill-certified stainless steel grades:
304, 316L, 444, AL29-4C
100% stainless steel construction, including supports, hardware, and all components.
Sizes
Available in round configurations from 6″ to 48″ in diameter. Custom sizes and configurations available — contact our engineering team.
Temperature Ratings
Continuous: 1400°F
Intermittent: 1800°F
2100F intermittent (10 minute) Temperature Rating
Pressure Rating
Suitable for negative, neutral, and up to 90” WC positive pressure applications.
Listings & Certifications
UL 1777 — Category I gas and oil-fired appliances
UL 103 & UL 103 HT Factory-built chimneys
UL 2561 — Chimney liners
UL 1738 — Special Gas Vent Standard
Construction
Factory-built Double-wall design
UL-listed fittings and accessories available
Suitable for breeching, relining, new construction, and retrofit applications
Warranty
Lifetime Warranty
Need help specifying your system?
Our in-house engineering team provides complete design assistance, structural calculations, and drafting support for projects of any scale.