4" X 25' Silver Jacket Flex Duct, R4.2

Product Overview

The JP Lamborn MHP25B-04 Flexible Air Duct is an R-4.2 insulated air distribution component designed for residential and light commercial HVAC applications. Constructed with a durable silver vapor-barrier jacket, a fiberglass insulation layer, and a wire-reinforced inner core, this duct provides reliable airflow performance and thermal efficiency. The flexible design facilitates professional installation while maintaining compliance with mechanical and energy code requirements for air distribution systems.

Technical Specifications

• Model: MHP25B-04
• Manufacturer: JP Lamborn (Hart & Cooley)
• Series: Residential
• Product Type: Insulated Flexible Air Duct
• Inside Diameter: 4 inches
• Length: 25 feet
• Insulation Value: R-4.2
• Outer Jacket: Silver vapor-barrier jacket for moisture resistance and mechanical protection
• Air Velocity Rating: 5000 fpm (maximum)
• Temperature Range: -20°F to 140°F (-29°C to 60°C)
• Core Construction: Helically wound, wire-reinforced inner core
• Insulation Type: Thermal fiberglass blanket with polyethylene vapor barrier
• Application: Supply and return air distribution in HVAC systems
• Compliance: UL 181 Class 1 Air Duct; conforms to NFPA 90A and 90B standards
• Installation: Approved for use in conditioned and unconditioned spaces per mechanical code

Professional Notes

Install in accordance with JP Lamborn and SMACNA flexible duct installation guidelines. Fully extend duct runs to minimize static pressure loss and maintain designed airflow capacity. Support ducts at regular intervals to prevent sagging or compression of the insulation layer. Seal all connections using UL 181-approved mastic or tape to ensure air-tight performance. Avoid sharp bends, excessive compression, and exposure to sharp edges to preserve insulation and core integrity.

Summary

The JP Lamborn MHP25B-04 Flexible Air Duct is a 4-inch diameter, 25-foot R-4.2 insulated duct with a silver vapor-barrier jacket. Rated for 5000 fpm and -20°F to 140°F operation, it provides durable, thermally efficient, and code-compliant air distribution performance for professional HVAC installations.