Selkirk 4″ Diameter Adjustable Wall Thimble and Firestop for Round Type B Gas Vent, Aluminum Double Wall Accessory Design, 187704

Description

Product Overview

The Selkirk 4‑inch Adjustable Wall Thimble is engineered to meet the demanding requirements of modern HVAC systems while delivering a straightforward installation experience. Constructed from heavy‑gauge galvanized steel, the exterior shell provides exceptional resistance to rust, moisture, and the abrasive conditions often encountered in both indoor and outdoor environments. Inside, an aluminum double‑wall liner delivers rapid heat transfer and acts as a certified fire‑stop, complying with UL standards for Type B gas vent applications. The thimble’s precise dimensions—4 1⁄8″ to 7″ adjustable depth—allow it to accommodate a broad range of wall thicknesses, eliminating the need for additional shims or custom fabrication. Each unit includes a pre‑drilled 4‑inch opening that aligns perfectly with standard round vent pipes, ensuring a snug, airtight seal that prevents drafts and improves overall system efficiency. The design also incorporates a built‑in 1‑inch air gap to combustible materials, a critical safety feature that helps maintain code compliance and reduces the risk of fire spread. With a compact footprint of 9.4 × 9.4 × 3.9 inches and a lightweight profile of just 4.8 ounces, the thimble can be easily handled by a single installer, yet it offers the durability required for long‑term service in demanding commercial settings. Selkirk’s heritage of nearly a century in HVAC innovation is evident in the meticulous craftsmanship, rigorous testing, and thoughtful engineering that define this product, making it a reliable choice for professionals who demand both performance and peace of mind.

Usage

Designed for versatility, the Selkirk Adjustable Wall Thimble fits seamlessly into a variety of installation scenarios, from new construction residential homes to retrofits in industrial facilities and light‑commercial buildings. In residential applications, the thimble provides a clean, code‑compliant solution for venting furnaces, water heaters, and air‑handling units, ensuring that the required fire‑stop barrier is in place without sacrificing airflow efficiency. For industrial settings, where larger ductwork and higher temperature differentials are common, the robust galvanized steel construction stands up to the increased mechanical stresses and exposure to harsh chemicals, while the aluminum liner continues to deliver reliable fire protection. Light‑commercial environments, such as restaurants, retail spaces, and office buildings, benefit from the thimble’s quick‑adjust feature, which reduces installation time and labor costs, allowing HVAC technicians to focus on system performance and customer satisfaction. The product’s ability to maintain a consistent 1‑inch air gap to surrounding combustible materials makes it suitable for use in fire‑rated wall assemblies, where compliance with local building codes is non‑negotiable. Additionally, the thimble’s compact size and low weight simplify handling during ceiling or wall penetrations, and the pre‑drilled opening aligns perfectly with standard 4‑inch vent pipes, eliminating the need for additional cutting or machining. Whether you are installing a new HVAC system, upgrading an existing one, or performing routine maintenance, the Selkirk Adjustable Wall Thimble offers a reliable, code‑compliant, and cost‑effective solution that enhances safety and system efficiency.

Why Choose Us

Selkirk has been a trusted name in the HVAC industry for nearly a hundred years, and that legacy is reflected in every component of the Adjustable Wall Thimble. The company’s commitment to quality begins with the selection of premium materials: heavy‑gauge galvanized steel for the outer shell provides unmatched durability, while the aluminum double‑wall liner ensures rapid heat dissipation and reliable fire‑stop performance. Each thimble undergoes rigorous testing in Selkirk’s state‑of‑the‑art laboratories, where it is evaluated against UL fire‑stop standards, corrosion resistance protocols, and mechanical load requirements. This thorough validation process guarantees that the product not only meets but often exceeds industry expectations for safety and longevity. Beyond the product itself, Selkirk offers a comprehensive support network that includes technical assistance, detailed installation guides, and a responsive customer service team ready to address any questions or concerns. The company’s dedication to continuous improvement means that feedback from field professionals is actively incorporated into product refinements, ensuring that each new iteration delivers enhanced performance and ease of use. Moreover, Selkirk’s distribution network spans North America, providing fast and reliable delivery to contractors, distributors, and end‑users alike. By choosing Selkirk, you are investing in a solution that combines proven engineering, rigorous quality assurance, and a customer‑centric approach that together deliver peace of mind and superior value for any HVAC project.

Key Features

• Adjustable opening from 4 1⁄8″ to 7″ lets you fit a wide range of wall thicknesses without extra tools.
• Galvanized steel exterior resists rust and weather, extending service life in outdoor and indoor installations.
• Aluminum double‑wall liner heats quickly and provides a fire‑stop rating that meets UL standards for safety.
• Provides the required 1‑inch air gap to combustible materials, helping you stay compliant with building codes.
• Supported by Selkirk’s legacy of nearly a century of HVAC innovation and backed by responsive customer service.

FAQ

What wall thicknesses does this thimble accommodate?

The thimble adjusts from 4 1⁄8″ up to 7″, covering most residential and commercial wall constructions, including metal studs, wood framing, and mixed‑material assemblies.

Is this product UL‑tested for fire safety?

Yes, the design meets UL fire‑stop requirements for Type B gas vents, ensuring reliable protection in case of fire while maintaining the necessary airflow characteristics.

Can I install this thimble in a metal stud wall?

Absolutely. The adjustable design and sturdy galvanized steel construction make it suitable for metal, wood, and mixed‑material walls, providing a secure seal regardless of the framing type.

Do you offer any warranty or support?

Selkirk provides a limited warranty that covers material defects and offers a dedicated support team ready to assist with installation questions, troubleshooting, or replacement parts.

How does the 1‑inch air gap improve safety?

The required 1‑inch air space to combustible materials helps prevent heat transfer that could ignite surrounding structures, aligning with fire‑code regulations and enhancing overall building safety.