Choosing the right vent kit is critical for tankless water heater performance, safety, and code compliance. The wrong fit can cause airflow issues, installation delays, or costly returns.
This roundup focuses on the most relevant options for homeowners, contractors, and replacement shoppers who want dependable venting hardware that matches their heater type and wall layout.
Best 10 Condensing Tankless Water Heater Vent Kits Picks for 2026
Rheem Replacement Pick
3-Inch Indoor Vent Termination
- Direct replacement for SP20286
- Corrosion-resistant outdoor build
- Fits select RTGH-84DV and RTGH-95DV units
Best For: Rheem owners replacing a compatible indoor vent termination
Rinnai Universal Pick
11.5-Inch Horizontal Termination
- For compatible Rinnai non-condensing systems
- Weather-resistant plastic exterior part
- Compact wall termination with tidy finish
Best For: Rinnai non-condensing systems needing a horizontal wall exit
OEM Rheem Pick
- Genuine factory authorized replacement
- For Rheem, Ruud, and Richmond units
- Supports up to 10-inch walls
Best For: OEM replacement for compatible Rheem/Ruud/Richmond installs
OEM Condensing Termination
Rinnai 8.7" Horizontal Termination Kit
- Condensing compatible and wall-mounted
- Stainless steel build for indoor install
- Limited lifetime warranty included
Best For: Rinnai owners needing an OEM horizontal termination kit for condensing units
Flexible High-Efficiency Venting
DiversiTech 2-Inch Horizontal Vent Kit
- Supports horizontal or vertical installs
- Low-profile look conceals pipework
- All fittings included for installation
Best For: Users needing a flexible termination kit for high-efficiency appliances
OEM Non-Condensing Vent Kit
Rheem ProTech Horizontal Vent Cone Kit
- OEM genuine factory authorized parts
- Snap-lock design for leak-free connection
- Built for non-condensing tankless heaters
Best For: Rheem non-condensing tankless water heater owners
Vertical Concentric Vent Kit
Rheem RTG20282 Vertical Vent Termination Kit
- Fits 3 in. x 5 inch concentric vent
- Includes flashing, caps, and storm collar
- 1-year limited warranty
Best For: Vertical vent terminations for compatible Rheem tankless units
Adjustable Horizontal Vent Kit
Rheem RTG20280-1 Adjustable Horizontal Vent Kit
- 3 x 5 inch horizontal vent sizing
- Extends for walls up to 10 inches
- Includes wall plate, elbow, and hardware
Best For: Compatible Rheem horizontal vent installs with thicker walls
Rheem Replacement Pick – 3-Inch Indoor Vent Termination
If you need condensing tankless water heater vent kits for a Rheem indoor setup, this 3-inch vent termination kit is a direct replacement for SP20286. It is designed to help safely discharge exhaust from compatible Rheem tankless units while offering corrosion resistance and a cleaner exterior finish than exposed piping.
Best For: Owners of compatible Rheem RTGH-84DV or RTGH-95DV models who want an outdoor vent termination replacement.
Pros:
- Direct replacement for SP20286.
- Made from sturdy, corrosion-resistant materials for outdoor conditions.
- Compatible with Rheem RTGH-84DV and RTGH-95DV models.
- Can improve the look of the exterior wall compared with exposed pipes.
Cons:
- Compatibility is limited to specified Rheem models and related equipment.
- No included components are listed in the supplied details.
This is a practical fit-focused choice if you are replacing an existing Rheem termination and want the same style of vent outlet. The main value is straightforward compatibility and weather-ready construction, not broad universal use.
Rinnai Universal Pick – 11.5-Inch Horizontal Termination
Rinnai 223181 11-1/2” Universal Non-Condensing Plastic Horizontal Termination Ki, N/A
Check Price On AmazonFor buyers comparing condensing tankless water heater vent kits with non-condensing options, this Rinnai horizontal termination kit is a simple exterior-wall solution. It is made for compatible Rinnai non-condensing tankless water heaters and uses weather-resistant plastic to help protect the vent opening from rain, debris, and pests.
Best For: Rinnai non-condensing tankless water heater installations that need a compact horizontal wall termination.
Pros:
- Designed for compatible Rinnai non-condensing tankless water heaters.
- Weather-resistant plastic construction helps resist outdoor wear and corrosion.
- Compact 11-1/2 inch design creates a neat exterior finish.
- Helps shield the vent opening from rain, debris, and pests.
Cons:
- Intended for non-condensing systems, not condensing units.
- Compatibility depends on approved Rinnai venting systems.
This is a good wall-termination part if you are staying within Rinnai’s approved non-condensing setup. Its strengths are durability, simple exterior installation, and a tidy finish rather than broad cross-brand compatibility.
Universal Stainless Pick – 3×5 Stainless Vent Kit
If you want condensing tankless water heater vent kits with broader brand coverage, this 3″ x 5″ stainless steel kit is the most universal option here. It is designed for most 3″ x 5″ gas tankless water heaters, including Rinnai, Navien, Rheem, and A.O. Smith, and includes the main parts needed for installation.
Best For: Installers or homeowners who want a complete 3″ x 5″ vent kit for compatible tankless heaters across several brands.
Pros:
- Universal compatibility with many 3″ x 5″ gas tankless water heaters.
- Includes an elbow, straight pipe, clamp, and two trim rings.
- 304 stainless steel construction offers corrosion resistance and high-temperature tolerance.
- Compact design supports indoor air quality control and space-saving installs.
Cons:
- Only applies to systems using a 3″ x 5″ vent format.
- Total length is 32 inches, so it may not suit every layout.
This is the most flexible pick if you need a complete kit rather than a single termination piece. The stainless-steel construction and included parts make it a strong all-around choice for compatible tankless heater installs.
OEM Rheem Pick – Horizontal Cone Termination
This Rheem ProTech termination kit is a focused option for condensing tankless water heater vent kits only if your system matches the listed Rheem, Ruud, or Richmond application. It is a genuine factory authorized replacement designed for gas non-condensing water heaters and supports installations using additional venting and up to 10-inch walls.
Best For: Rheem, Ruud, or Richmond owners who need a genuine OEM horizontal vent cone termination.
Pros:
- Direct replacement for Rheem, Ruud, and Richmond water heaters.
- Genuine factory authorized part.
- Designed for use with additional venting to complete the installation.
- Built for up to 10-inch walls and includes hardware/instructions when applicable.
Cons:
- Made for non-condensing water heater applications.
- Compatibility is limited to specific brands and installation requirements.
Choose this if you want an OEM-style termination and already know your system calls for the listed Rheem ProTech part. It is a dependable replacement piece, but it is not a universal vent kit.
OEM Condensing Termination – Rinnai 8.7" Horizontal Termination Kit
If you need a clean, brand-matched option for condensing tankless water heater vent kits, this Rinnai horizontal termination kit is built for indoor installation and condensing compatibility. Its stainless steel construction and wall mount design make it a straightforward choice for users staying within Rinnai’s OEM accessory lineup.
Best For: Rinnai owners looking for a condensing-compatible horizontal termination kit with OEM fit and finish.
Pros:
- Designed for condensing tankless water heaters
- Stainless steel construction
- Wall mount, indoor installation style
- Limited lifetime warranty noted by the manufacturer
Cons:
- Specific to Rinnai applications
- Horizontal termination only
- Does not include broad multi-brand compatibility details
This is a practical pick if you want an OEM termination kit with a durable material and a purpose-built setup for condensing systems. It is best suited to buyers who value matching manufacturer accessories over universal flexibility.
Flexible High-Efficiency Venting – DiversiTech 2-Inch Horizontal Vent Kit
For shoppers comparing condensing tankless water heater vent kits and other high-efficiency appliance options, this DiversiTech termination kit offers a low-profile horizontal or vertical venting solution. The included fittings and concealed intake/exhaust layout make it a practical choice when you want a tidy outside finish and a kit that supports flexible installation.
Best For: Buyers who want a compact termination kit for high-efficiency appliances with flexible installation options.
Pros:
- Designed for high-efficiency fossil fuel appliances
- Includes all fittings needed for installation
- Low-profile design hides intake and exhaust pipework
- Can be used for horizontal or vertical installation
Cons:
- Not described as a dedicated condensing-only water heater kit
- Specific vent sizing may limit compatibility
- Does not focus on OEM branding for a single heater line
This kit stands out for its practical, clean appearance and broad high-efficiency appliance use case. If you want a flexible vent termination setup with everything included, it is a solid, installation-friendly option.
OEM Non-Condensing Vent Kit – Rheem ProTech Horizontal Vent Cone Kit
If your search for condensing tankless water heater vent kits also includes models that are not condensing, this Rheem ProTech kit is a purpose-built OEM option for non-condensing tankless gas heaters. It uses an exclusive snap-lock design for leak-free connection and comes with rugged metal construction for a more durable installation.
Best For: Rheem owners with non-condensing tankless gas water heaters who want an OEM horizontal vent termination kit.
Pros:
- OEM genuine factory authorized parts
- Exclusive snap-lock design for leak-free connection
- Rugged metal construction for added durability
- Includes hardware and instructions when applicable
Cons:
- Made for non-condensing water heaters only
- Specific 2 in. x 6 in. wall fitment
- 1-year limited warranty is shorter than some alternatives
This is a strong match if you need a Rheem-specific vent termination kit and want factory-authorized parts. It is less relevant for condensing models, but it is a well-defined option for the correct non-condensing application.
Compact 2-Inch Wall Vent Kit – SP20285 Horizontal Vent Termination Kit
If you need condensing tankless water heater vent kits for a 2-inch setup, the SP20285 horizontal vent termination kit is built for clean through-the-wall venting. It is designed to vent high-efficiency fossil fuel appliances and helps conceal intake and exhaust pipework for a cleaner exterior finish.
Best For: Homeowners who already have 2-inch PVC or ABS piping and want a flush-mounted horizontal termination kit for a tankless heater or similar high-efficiency appliance.
Pros:
- Includes the horizontal vent termination and screws for a straightforward install.
- Designed for 2-inch PVC and ABS piping, which is ideal if your system matches that size.
- Flush-mount design helps keep the outside wall looking neat.
- Intended for high-efficiency appliances, including tankless water heaters and furnaces.
Cons:
- Only fits 2-inch piping, so size compatibility must be confirmed first.
- Intake and exhaust pipes are sold separately.
- Best suited to installations that need a horizontal wall termination, not vertical venting.
Overall, this is a practical choice if you need a simple, included-parts solution for a 2-inch condensing vent termination. The main value is its clean wall appearance and straightforward fit for the specified pipe size.
Vertical Concentric Vent Kit – Rheem RTG20282 Vertical Vent Termination Kit
When comparing condensing tankless water heater vent kits, this Rheem ProTech vertical vent termination kit stands out for installations that need a direct vertical path. It is made for 3 in. x 5 inch concentric venting and includes the key flashing, caps, and storm collar pieces needed to help complete the setup.
Best For: Rheem-compatible non-condensing tankless gas water heater installs that require a vertical vent termination with the listed 3″ x 5″ concentric format.
Pros:
- Fits 3 in. x 5 inch concentric vent systems.
- Includes flashing, caps, and storm collar.
- Uses galvanized and stainless steel finish materials.
- Backed by a 1-year limited warranty.
Cons:
- Designed for non-condensing tankless gas water heaters, not all venting systems.
- Vent pipe is still required to complete installation.
- Vertical configuration may not suit wall-vent projects.
This is a solid option if your installation calls for a vertical concentric termination and you want the main roof-penetration components included. Just verify compatibility with your heater and vent size before buying.
Adjustable Horizontal Vent Kit – Rheem RTG20280-1 Adjustable Horizontal Vent Kit
For condensing tankless water heater vent kits that need a horizontal through-the-wall setup, the Rheem RTG20280-1 offers a stainless steel termination system built for 3 x 5 inch venting. It includes a 12 inch wall plate, a 94 degree elbow, and hardware, with support for wall thicknesses up to 10 inches.
Best For: Rheem EcoSense mid-efficiency tankless gas indoor direct vent units that need a durable horizontal wall termination and adjustable wall thickness support.
Pros:
- Stainless steel construction for durability and corrosion resistance.
- Includes a complete wall plate assembly with mounting screws.
- 94 degree elbow is included to help with venting configuration.
- Can be extended for walls up to 10 inches thick.
Cons:
- Made specifically for Rheem EcoSense mid-efficiency tankless gas indoor direct vent units.
- Only supports the listed 3 x 5 inch horizontal vent size.
- Not intended for non-Rheem or mismatched venting setups.
If you need a horizontal termination with more wall-thickness flexibility, this kit is one of the more complete options in the group. Its stainless steel build and included fittings make it especially practical for compatible Rheem installations.
How We Picked the Best Condensing Tankless Water Heater Vent Kits
We prioritized compatibility, vent material, termination style, wall thickness range, and overall suitability for tankless installs. For condensing units, the most important factors are approved venting materials and the correct termination configuration for the specific heater brand and model.
We also favored kits that clearly define pipe diameter and installation use case, since Condensing Tankless Water Heater Vent Kits are not interchangeable with non-condensing systems in many applications.
Quick Comparison
Think in terms of three variables: heater type, vent path, and wall penetration. Horizontal termination kits are the most common for sidewall installs, while vertical options are used when the vent exits through the roof or a taller chase. Material matters too: stainless steel and manufacturer-specific kits tend to be the safest choice for demanding applications.
Key Buying Factors for Condensing Tankless Water Heater Vent Kits
Compatibility First
Confirm whether your heater is condensing or non-condensing, then match the vent kit to the exact brand and model family. Many kits look similar but are not approved across systems.
Vent Material and Diameter
Condensing systems often require corrosion-resistant materials and the correct pipe sizing to handle cooler, moisture-laden exhaust. Check the required diameter before ordering any kit.
Termination Orientation
Choose horizontal or vertical based on your install route. Also verify wall thickness limits and included cone, cap, or adapter pieces so the termination seals correctly.
Installation Hardware
Small items such as screws, gaskets, and adapters can save time during install. If these are not included, factor in the extra parts needed to complete the job.
Who Should Buy Which Condensing Tankless Water Heater Vent Kits?
Homeowners replacing an existing setup should start with the exact OEM-style match for their current heater. Contractors handling mixed jobs may prefer flexible, universal, or stainless-steel options when the system approval allows it. If you are outfitting a condensing unit, focus on kits explicitly intended for that category rather than generic vent terminations.
For the safest results, always confirm local code, manufacturer instructions, and venting clearances before purchasing. A correctly matched kit is the easiest way to protect efficiency, reliability, and warranty coverage.
