FasNSeal Special Gas Venting

FasNSeal special gas venting is a stainless steel venting system built for Category II, III, and IV natural gas and propane appliances that produce pressurized or condensing exhaust a standard chimney can't safely handle. Manufactured by DuraVent, the system uses a mechanical locking band and triple-lipped directional gaskets at every joint instead of solvent cement or high-temperature sealant, which speeds up field assembly and keeps every joint sealed the same way. Vent sections and fittings are available from 3 inches through 16 inches in diameter, covering everything from a single tankless water heater to a large commercial boiler plant. The system is rated for a maximum flue gas temperature of 480 degrees Fahrenheit and a maximum positive pressure of 15 inches water column, and it carries UL Listing to UL 1738 along with ULC S636 certification for use in Canada.

Subcategories

• Standard FasNSeal Pipe and Fittings: Standard FasNSeal components are built from 29-4C or 316L stainless steel, with wall thickness increasing from .016 inch on 3 to 7 inch diameters up to .024 inch on the largest 14 to 16 inch sizes. Installers use standard rigid sections and fittings to vent Category II, III, and IV appliances such as high-efficiency boilers and commercial water heaters. The mechanical locking band at each joint lets a crew assemble a run without a torch or solvent cement.
• FasNSeal Flex: FasNSeal Flex is a flexible version of the system designed for appliances such as tankless water heaters, pool heaters, and unit heaters where the vent run needs to navigate tight turns or an irregular chase. Contractors reach for flex sections on retrofit jobs where rigid pipe would require extra fittings or structural changes to route around obstacles. Flex sections still carry the same Category II through IV appliance rating as the rigid system.
• FasNSeal 80/90: FasNSeal 80/90 is built specifically to let a condensing 90-plus efficiency appliance share venting infrastructure with an existing atmospheric Category I appliance in the same vent run. Retrofit projects that are adding a high-efficiency unit alongside older atmospheric equipment use this system to avoid running a completely separate vent path. The patent-pending design addresses the different exhaust characteristics of condensing versus atmospheric appliances within the same physical vent.
• FasNSeal W2 Reduced Clearance System: FasNSeal W2 is built for installations where the vent run needs reduced clearance to combustible materials compared to the standard system's clearance requirement. Commercial installers specify W2 components when the mechanical room or chase space is too tight to meet standard clearance rules with the base FasNSeal product. The reduced-clearance rating still carries the same UL 1738 listing as the rest of the FasNSeal line.

Buying Guide

Selecting FasNSeal components starts with confirming the connected appliance's category rating, since the system is built for Category II, III, and IV gas and propane equipment rather than standard atmospheric Category I appliances that vent through a conventional chimney. Diameter comes next, matched to the appliance manufacturer's venting requirements rather than to whatever pipe happens to already be run, since the available sizes span 3 through 16 inches to cover everything from a single tankless unit to a commercial boiler plant.

Routing determines which product line within the system fits the job. A straight run through open mechanical room space works with standard rigid FasNSeal pipe and fittings, while a run that has to navigate tight turns or an irregular chase calls for FasNSeal Flex instead. For FasNSeal Special Gas Venting specifically, retrofit jobs adding a high-efficiency condensing appliance alongside existing atmospheric equipment should look at the FasNSeal 80/90 line, which is built to let both appliance types share venting infrastructure.

Clearance to combustibles is the last major check, and it varies between the standard system and the FasNSeal W2 reduced-clearance option. Confirming the available clearance in the actual mechanical space before ordering determines which line meets code without requiring extra fire-rated shielding around the vent run.

Frequently Asked Questions

What appliance categories is FasNSeal rated for?

FasNSeal is rated for Category II, III, and IV natural gas or propane appliances, which cover pressurized and condensing exhaust conditions that a standard Category I atmospheric vent can't handle. Confirming the connected appliance's category rating is the first step before selecting any vent components.

What's the maximum temperature and pressure FasNSeal is rated for?

The system carries a maximum flue gas temperature rating of 480 degrees Fahrenheit and a maximum positive pressure rating of 15 inches water column. Both ratings apply across the standard product line and are confirmed under its UL 1738 listing.

When would a project use FasNSeal Flex instead of standard rigid pipe?

FasNSeal Flex is the better choice when the vent run needs to navigate tight turns or an irregular chase that would otherwise require several extra rigid fittings. Retrofit jobs on tankless water heaters, pool heaters, and unit heaters commonly use flex sections for this reason.

Can a new high-efficiency appliance share a vent with an existing atmospheric unit?

Yes, the FasNSeal 80/90 system is built specifically to let a condensing 90-plus efficiency appliance share venting infrastructure with an existing Category I atmospheric appliance in the same run. This avoids running a completely separate vent path during a retrofit.

Does FasNSeal need special clearance to combustible materials?

Standard FasNSeal components have their own listed clearance requirement, and the FasNSeal W2 line is available specifically for installations that need a reduced clearance to combustibles compared to the standard system. Checking the available space in the mechanical room against both options determines which line meets code without additional fire-rated shielding.