If you’re upgrading or installing a tankless gas water heater, a 3×5 concentric vent pipe is a key detail for safe, efficient exhaust and air intake. This guide highlights five reliable options, helps you compare compatibility, and shows who benefits most from each kit. Ideal buyers include homeowners replacing a vent kit, contractors seeking standard parts, and DIY installers aiming for straightforward, code-friendly setups.
| Product | Brand | Type | Length / Size | Best For |
|---|---|---|---|---|
| Rheem ProTech RTG20320 Concentric (3″/5“) Adjustable Vent Kit 21″ – 35″ In | Rheem | Concentric Vent Kit | Adjustable 21″–35″ | Best for adjustable installations on Rheem tankless units |
| Rheem ProTech Vertical Vent Termination Kit for Tankless Gas Non-Condensing Water Heaters – RTG20282 (3″ x 5″) | Rheem | Vertical Termination Kit | 3″ x 5″ | Best for vertical up-vent installations |
| Dura Vent 35CVS-36 3 x 5 in. Concentric Vent System Pipe – 36 in. Length | Dura Vent | Concentric Vent Pipe | 36 in. | Best for longer, straight runs |
| Dura Vent 35CVS-24 3 x 5 in. Concentric Vent System Pipe – 24 in. Length | DuraVent | Concentric Vent Pipe | 24 in. | Better for mid-length installations |
| 3″x5″ Vent Kit, Compatible with Navien Rinnai Rhemm A.O. Smith 12″ Stainless Steel Pipe for Tankless Water Heaters, 304 Stainless Steel | VATTCEEL | Vent Kit | 12″ straight pipe | Best for universal compatibility and quick setup |
Rheem ProTech RTG20320 Concentric Vent Kit
- Concentric vent pipe with 3”/5” sizing, compatible with many tankless models.
- Adjustable vent length from 13 inches to 10 inches, with cut-to-size capability.
- Stainless steel construction for durability and corrosion resistance.
Best for: Installers seeking an adjustable Rheem-ready solution for 3×5 concentric venting. Caution: Verify compatibility with your specific Rheem model and local code requirements before installation.
Rheem ProTech Vertical Vent Termination Kit
- Designed for 3″ x 5″ concentric vent systems, includes flashing, caps, and storm collar.
- Galvanized and stainless steel finish offers weather resistance for outdoor or semi-exposed installations.
- Best for vertical exhaust runs on non-condensing tankless water heaters.
Best for: Projects needing a complete termination assembly with weatherproofing components. Caution: Ensure the surface is suitable for flashing installation and matches your vent route.
Dura Vent 35CVS-36 Concentric Pipe
- 3 x 5 inch size with a 36-inch length, suitable for longer straight runs.
- Durable stainless composition suitable for high-temperature venting needs.
- Easy to fit into standard 3×5 concentric vent configurations.
Best for: Installations requiring a longer, continuous vent segment with reliable stainless construction. Caution: Check local venting length limits and clearance requirements.
Dura Vent 35CVS-24 Concentric Pipe
- 3″ x 5″ size with a 24-inch length, fitting mid-length runs.
- Durable stainless steel for corrosion resistance in venting environments.
- Best for compact installations where space is limited yet a 3×5 vent is required.
Best for: Mid-length applications needing a compact, durable vent segment. Caution: Shorter length may require additional segments for longer runs.
3×5 Vent Kit by VATTCEEL
- Universal compatibility with many 3″ x 5″ gas tankless water heaters, including Rinnai, Navien, Rheem, and A.O. Smith.
- Includes a 12-inch straight pipe for quick setup and straightforward alignment.
- Constructed from 304 stainless steel for corrosion resistance and high-temperature tolerance.
Best for: Installers seeking a widely compatible venting option with a shorter straight segment. Caution: Confirm that the kit’s length fits your particular installation path.
Buying Guide
What matters most with 3×5 concentric vent pipes?
Durability, corrosion resistance, and compatibility with your heater’s venting requirements top the list. Stainless steel options typically perform better in high-heat environments and resist oxidation over time.
Which length should you choose?
Choose a length that matches your installation route. Shorter runs (like 12–24 inches) work well for compact spaces or retrofit jobs, while longer sections (36 inches) suit straight, unobstructed runs.
Concentric vs. straight vent choices
Concentric systems combine vent exhaust and air intake into a single pipe, which can simplify routing and reduce external clearances. A separate straight pipe is sometimes preferred for extended runs or when fitting a particular brand’s termination kit.
Brand and kit compatibility
Rheem kits are typically best for Rheem units, while DuraVent and VATTCEEL products offer broader compatibility. Always verify that the kit’s inner diameter, exterior finish, and mounting hardware suit your heater model and local code requirements.
Installation considerations
Follow manufacturer instructions and local code guidelines for clearance, flashing, and termination. Use weatherproof seals where applicable, and ensure proper support and slope to prevent condensate buildup.
FAQ
- Q: Can I mix brands for a 3×5 vent system? A: Mixing components is not recommended unless explicitly stated by the heater manufacturer and vent kit documentation. Compatibility matters for performance and safety.
- Q: Do these kits require professional installation? A: Installation is often best performed by a qualified HVAC technician, especially for vent routing, clearance, and termination seals.
- Q: Are 3×5 concentric pipes suitable for all tankless heaters? A: Most are designed for common 3×5 gas tankless heaters, but always confirm with your unit’s specifications and the kit’s afifinity.
- Q: What is the advantage of a longer vent length? A: A longer length can accommodate more complex routing or building constraints, but may require more sealing and support components.
- Q: Is stainless steel necessary for outdoor installations? A: Stainless steel offers better weather and corrosion resistance, making it a safer choice for exposed outdoor runs.