DuraVent Type B Venting Installation Guide

BY Collin Champagne Aug 29, 2025

Simpson Dura-Vent's Type B Gas Vent system is for use with natural gas or liquid propane category I and draft hood equipped appliances, and appliances tested and listed to use Type B Gas Vent for a wide range of applications, including: natural gas fireplaces, gas-fired furnaces, boilers, water heaters, and wall or space heating applications.

Simpson Dura-Vent's Type B Gas Vent systems are UL Listed to UL 441 and UL 1777 (MH6357). ULC Listed to ULC S605 (CMH1276 & CMH1407).

How Size and Height Affect Stove Performance

The amount of heat the vent gases lose as they flow determines how much condensation will occur and how strong the draft will be. To control the heat loses, proper selection of venting materials is of vital importance.

A Type B Gas Vent Sizing Handbook is available to assist you with the proper installation. Click HERE to view online.

Vent Termination Chart

Using listed Type B Gas Vent caps may terminate in accordance with this table.

Gas Vent Specification Chart

NOTES

1. Clearance to combustibles is the air space between vent and combustibles.

2. Maximum height varies with equipment over 50", for taller applications refer to SDV sizing handbook 2. (L202). 14"-16" Require screws.

3. When oval is used on wall furnaces, minimum height required from bottom of furnce to cap is 12", minimum 16" stud space.

4. Limited by sizing tables.

5. 18" pipe OD is one inch larger than ID and 20" - 30" OD is 2" greater than ID.

About the Author

Collin Champagne

With over 13 years in the industry, Collin is a National Fireplace Institute (NFI) certified technician and managed content for the eFireplacestore and eCanopy brands. He has achieved the highest NFI certification possible as a Master Hearth Professional and is certified in all three hearth appliance fields: wood, gas, and pellet. With experience with sales and in-field installations, his expertise shines through his technical knowledge and way with words.

Contact our NFI-Certified Experts

Customer Q&A with Product Specialists

John from Massachusetts asked:

My furnace non-direct vent is 4 feet below my termination cap for my fireplace DV360RP. Is that okay?

Vent termination clearance requirements are specific to each appliance and vent system. Therefore, we cannot confirm if a 4-foot vertical offset between your furnace vent and fireplace Type B vent termination cap meets code without knowing the exact make and model of both units, as well as the distance between the vents. Please provide the make and model number of your furnace and fireplace (specifically confirming the Majestic DV360RP) as found on the appliance data plate, so we can consult the manufacturer's installation manuals and applicable clearance requirements. Because this affects vent-to-vent clearance and draft performance, we also recommend having an NFI Certified professional inspect the installation on-site to ensure it meets code. You can find local certified professionals here: NFI Certified Pros.

Answered by: Nevins P. on Aug 17, 2026

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