Answering your search for reliable 3×5 concentric vent pipes, this guide highlights five solid choices for tankless water heaters. These are best for homeowners replacing venting, installers seeking standard sizes, and users prioritizing durability and corrosion resistance. Each option is evaluated for best use case, installation practicality, and potential limitations. Below, you’ll find a quick buying table, followed by detailed product sections and a practical buying guide to help you compare features side by side.
| Product | Best For | |
|---|---|---|
| Rheem ProTech RTG20320 Concentric Vent Kit | Best for adjustable vent lengths | 13″ to 10″ adjustable |
| Rheem ProTech RTG20282 Vent Termination Kit | Best for complete termination with flashing | 3″ x 5″ |
| Dura Vent 35CVS-36 Concentric Pipe | Best for long runs | 36″ length |
| Dura Vent 35CVS-24 Concentric Pipe | Best for mid-length installations | 24″ length |
| VATTCEEL 3″x5″ Vent Kit | Best universal compatibility | 12″ straight pipe |
Rheem ProTech RTG20320 Concentric (3″/5“) Adjustable Vent Kit 21″ – 35″ In
Best For: Homeowners installing or replacing an adjustable vent path for a tankless gas water heater. This kit uses a stainless steel concentric vent pipe and offers adjustability from 21″ to 35″ overall, with a 13″ to 10″ expansion range. Choose this if you anticipate needing to tune the vent length on-site to fit varying installation clearances. Limitation: adjustable kits may require precise trimming and sealing during installation to maintain proper venting performance.
Rheem ProTech Vertical Vent Termination Kit for Tankless Gas Non-Condensing Water Heaters
Best For: Installers seeking a complete termination kit for 3″ x 5″ concentric vent systems. It includes flashing, caps, and storm collar with galvanized and stainless steel finishes, making it suitable for durable, all-season vent termination. Limitation: requires proper matching with compatible vent pipe sections and flashing components for a leak-free installation.
Dura Vent 35CVS-06 3 x 5 in. Concentric Vent Stainless Steel Inner Pipe
Best For: Quick replacement of a short concentric vent segment where stainless steel inner pipe is essential for corrosion resistance. Limitation: the 6″ length is short, which may require multiple pieces for longer runs or complex routing.
Dura Vent 35CVS-36 3 x 5 in. Concentric Vent System Pipe
Best For: Long vent runs where a 3″ x 5″ concentric system needs to extend across substantial distance. It offers a 36″ length with easy in-and-out fit. Limitation: longer segments may require careful alignment and support to maintain a straight, efficient vent path.
Dura Vent 35CVS-24 3 x 5 in. Concentric Vent System Pipe
Best For: Mid-length vent installations where a straight, reliable 24″ piece meets the run requirements. It provides easy installation with a 3″ x 5″ size and standard stainless construction. Limitation: may require additional pieces to complete longer paths or complex routing.
VATTCEEL 3″x5″ Vent Kit for Tankless Water Heaters
Best For: Universal compatibility with many 3″ x 5″ gas tankless water heaters from Rinnai, Navien, Rheem, and A.O. Smith. Includes a 12-inch straight pipe for easy setup and is fabricated from durable 304 stainless steel for corrosion resistance and heat tolerance. Limitation: length is limited to the included straight section, which may require additional pieces for longer runs.
Buying Guide
Key considerations when selecting a 3×5 concentric vent pipe for tankless water heaters include compatibility with your heater model, length requirements, and environmental exposure. The following questions can help you compare options:
- Do you need adjustable length or a fixed run? If your installation has variable clearances, an adjustable kit like the Rheem RTG20320 provides flexibility.
- Is complete termination hardware included? Termination kits with flashing and storm collars simplify installation and reduce leakage risk, as seen in the Rheem RTG20282.
- What material best suits your environment? Stainless steel inner pipes resist corrosion in humid spaces; some DuraVent options emphasize corrosion resistance and US-made construction.
- What is the required length for your run? Longer pieces (36″ or more) reduce joints but require careful alignment; shorter pieces may need multiple segments.
- Is universal compatibility important? A universal vent kit can accommodate many brands, saving time if you have a mixed-origins installation.
FAQ
- What does 3×5 mean in a concentric vent pipe?
It refers to the inner pipe diameter (3 inches) and the outer pipe diameter (5 inches) used for venting a tankless water heater. - Can I mix brands for concentric vent components?
Compatibility varies; check the product datasheets for approved brand pairings and venting codes. - Do these kits include all necessary hardware?
Most listings specify if flashing, caps, or storm collars are included; verify before purchasing. - Which length is best for a short run?
Shorter lengths like 12–24 inches are ideal for tight spaces, while longer pieces are better for extended runs with fewer joints. - Is stainless steel essential for outdoor installations?
Stainless steel offers superior corrosion resistance in exposed environments, though some galvanized parts may be suitable indoors. - What installation considerations matter most?
Ensure a secure, airtight seal, proper clearance from combustibles, and correct outdoor termination orientation.