Centrotherm isia0203-4 Increaser 2 to 3 Inch Innoflue Vent

Product Description

The CENTROTHERM isia0203-4 is a single-wall increaser fitting for the InnoFlue polypropylene venting system, designed to transition exhaust vent pipe from a 2-inch diameter to a 3-inch diameter. It maintains flow continuity through a concentric design that avoids abrupt turbulence at the transition point. This increaser is evaluated to UL1738 and ULCS636 by ICC, confirming compliance with North American standards for gas appliance venting components. HVAC technicians and plumbers install this fitting when upsizing a vent run to meet appliance manufacturer requirements or to reduce system backpressure over longer vent runs.

The isia0203-4 is suited for residential and light commercial direct-vent and exhaust-only applications using InnoFlue single-wall polypropylene pipe. Typical installations include high-efficiency condensing furnaces, boilers, and water heaters that require polypropylene venting due to low flue gas temperatures and condensate conditions. This fitting is used when the vent diameter must increase mid-run, at appliance collars, or at transitions between vent segments of different sizes.

Key Features

• Transitions vent pipe from 2 inches to 3 inches in a single fitting
• Evaluated to UL1738 and ULCS636 by ICC for compliant installations
• Single-wall polypropylene construction — durable and lightweight
• Installs without glues, primers, or solvents for faster service
• Concentric design maintains airflow and minimizes turbulence at the transition

Compatibility

Designed for use with the CENTROTHERM InnoFlue single-wall polypropylene venting system in diameter combinations requiring a 2-inch to 3-inch increaser transition.

Installation Notes

Installation should be performed by a licensed HVAC technician or plumber in accordance with the appliance manufacturer instructions and applicable mechanical codes such as the IFGC or IMC. Power down and shut off gas supply to the connected appliance before servicing any vent components. No adhesives or solvents are required for this fitting — follow the InnoFlue system assembly instructions for proper joint engagement and support spacing. Verify the completed vent system is leak-free and properly supported before returning the appliance to service.

Technical Specifications

• Inlet Diameter: 2 inches
• Outlet Diameter: 3 inches
• Wall Type: Single Wall
• Certifications: UL1738, ULCS636 (evaluated by ICC)
• Installation Method: No glues, primers, or solvents required

Standard Information

• Brand: CENTROTHERM
• Manufacturer Part Number: isia0203-4