Choosing the right vent termination kit is critical for a tankless water heater setup that runs safely, efficiently, and within code. The best option depends on your heater type, vent diameter, and wall thickness.
This roundup highlights 10 sidewall vent kits for tankless water heaters, with a focus on compatibility, build quality, and installation fit for common residential applications.
Best 10 Sidewall Vent Kits for Tankless Water Heaters Picks for 2026
Low-Profile Universal Pick
DiversiTech HVENT2 2-Inch Horizontal Vent Termination Kit
- Works for horizontal or vertical installs
- Includes fittings for installation
- Low-profile look hides pipework
Best For: Clean, flexible vent termination on high-efficiency gas appliances
Stainless Steel Universal Pipe
3x5 Vent Kit, 12-Inch 304 Stainless Steel
- Fits many 3" x 5" tankless systems
- 304 stainless steel for durability
- Compact 12-inch straight pipe
Best For: A durable pipe section for compatible 3" x 5" tankless venting
Brand-Matched Termination Kit
Rinnai 223174PP Horizontal Termination Kit
- Made for condensing tankless heaters
- Stainless steel wall-mounted kit
- Backed by limited lifetime warranty
Best For: Compatible Rinnai condensing tankless water heater installations
Low-Profile Sidewall Vent Pick
SP20285 Horizontal Vent Termination Kit for 2-inch
- Conceals intake and exhaust pipework
- For 2-inch PVC and ABS pipes only
- Includes screws for outside-wall installation
Best For: Homeowners needing a tidy horizontal sidewall vent termination
Premium Vertical Vent Choice
Rheem ProTech RTG20282 3" x 5" Concentric Kit
- Fits 3 in. x 5 in. concentric vent systems
- Includes flashing, caps, and storm collar
- Built with galvanized and stainless steel finish
Best For: Compatible Rheem owners needing a vertical concentric termination kit
Stainless Steel Vent Pipe Kit
GASLAND 3" Horizontal Vent Package
- Includes hood, elbow, pipes, wall thimble, and clamps
- T304 stainless steel construction
- For gas tankless heaters with a 3-inch exhaust port
Best For: Buyers wanting a complete 3-inch horizontal vent kit
Compact Wall Kit for 2-In. Vent Runs
Rheem ProTech Horizontal Vent Cone Termination Kit
- OEM factory-authorized parts
- Snap-Lock design for leak-free connection
- Stainless steel construction
Best For: 2 in. x 6 in. wall installs on compatible non-condensing Rheem units
Adjustable 3 x 5 Wall Vent Kit
Rheem RTG20280-1 ProTech Horizontal Vent Termination Kit
- Extends to fit walls up to 10 inches
- Includes 12-inch wall plate and screws
- Stainless steel components with 94-degree elbow
Best For: Compatible Rheem non-condensing gas tankless heaters needing an adjustable wall-depth kit
Low-Profile 2-In. Wall Vent Kit
Rheem ProTech Horizontal Vent-Cone Termination Kit
- Low-profile cone termination
- Fits walls up to 12 inches
- Includes elbow, trim ring, and screws
Best For: Compatible Rheem non-condensing systems needing a low-profile deeper-wall termination
Low-Profile Universal Pick – DiversiTech HVENT2 2-Inch Horizontal Vent Termination Kit
If you need sidewall vent kits for tankless water heaters that keep the exterior neat, the DiversiTech HVENT2 is built for horizontal or vertical termination on high-efficiency gas appliances. It includes the needed fittings and is designed to conceal intake and exhaust piping for a cleaner finish.
Best For: Homeowners or installers who want a low-profile vent termination kit that works with tankless water heaters and other high-efficiency fossil fuel appliances.
Pros:
- Designed for horizontal through-the-wall or vertical through-the-roof installations
- Includes all fittings needed for installation
- Low-profile design helps hide intake and exhaust pipework
- Suitable for tankless water heaters, furnaces, and similar appliances
Cons:
- Only the termination kit is included, not a full venting system
- Fit still depends on confirming your appliance and pipe setup
This is a practical choice if you want a straightforward termination kit that prioritizes a clean exterior look and flexible installation options.
Stainless Steel Universal Pipe – 3×5 Vent Kit, 12-Inch 304 Stainless Steel
This sidewall vent kit for tankless water heaters is a simple straight-pipe option for 3″ x 5″ systems. It is designed for compatibility with major brands like Rinnai, Navien, Rheem, and A.O. Smith, while the 304 stainless steel build adds corrosion resistance and high-temperature durability.
Best For: Buyers who need a compact 3″ x 5″ stainless steel vent pipe for a compatible tankless water heater setup.
Pros:
- Compatible with many 3″ x 5″ tankless water heaters from major brands
- 304 stainless steel construction for corrosion resistance and heat tolerance
- Compact 12-inch length works well in space-saving installations
- Helps direct exhaust outdoors to support indoor air quality control
Cons:
- Includes only one straight pipe, not a complete termination kit
- Requires a matching 3″ x 5″ vent configuration
If your system already matches the size and you only need a durable pipe section, this is a focused, no-frills option.
Flushed Wall Termination Kit – SP20285 Horizontal Vent Termination Kit
For shoppers comparing sidewall vent kits for tankless water heaters, the SP20285 is a horizontal vent termination kit made for 2-inch PVC and ABS piping. It is designed to flush mount to an outside wall, includes screws and instructions, and aims to keep the intake and exhaust layout clean and simple.
Best For: Installers who need a horizontal termination kit for 2-inch PVC or ABS vent piping with a flush outside-wall finish.
Pros:
- Fits 2-inch PVC and ABS piping
- Flush-mount design for a cleaner outside-wall appearance
- Includes screws and instructions for easier installation
- Made for high-efficiency tankless water heaters and furnaces
Cons:
- Only fits 2-inch piping, so size must be confirmed first
- Designed as a termination kit, not a complete vent pipe system
This is a sensible pick when the pipe size matches and you want a tidy, wall-mounted termination with the basics included.
Brand-Matched Termination Kit – Rinnai 223174PP Horizontal Termination Kit
If you want sidewall vent kits for tankless water heaters from the appliance brand itself, the Rinnai 223174PP is a horizontal termination kit made for condensing tankless water heaters. Its stainless steel construction and wall-mount design make it a straightforward match for indoor-installation setups.
Best For: Owners of compatible Rinnai condensing tankless water heaters who want a brand-matched horizontal termination kit.
Pros:
- Designed specifically for condensing tankless water heaters
- Wall-mounted horizontal termination format
- Stainless steel construction
- Limited lifetime warranty from the manufacturer
Cons:
- Brand-specific fit limits use to compatible Rinnai setups
- Does not appear to include the broader vent piping system
This is the most straightforward option when you already have a compatible Rinnai system and want a purpose-built termination kit backed by a warranty.
Low-Profile Sidewall Vent Pick – SP20285 Horizontal Vent Termination Kit for 2-inch
If you need sidewall vent kits for tankless water heaters, this SP20285 horizontal termination kit is built for venting high-efficiency fossil fuel appliances while keeping the outside wall looking cleaner. It is designed to conceal both the intake and exhaust pipework and comes with screws for a straightforward install, but it is only suitable for 2-inch PVC and ABS pipes, so sizing matters before you buy.
Best For: Buyers who want a low-profile outside-wall vent termination for compatible 2-inch PVC or ABS tankless heater venting.
Pros:
- Conceals intake and exhaust pipework for a neater exterior wall
- Designed for safe venting of high-efficiency fossil fuel appliances
- Works for horizontal through-wall and vertical through-roof installations
- Includes screws and is meant to avoid extra outside connection fittings
Cons:
- Only suitable for 2-inch PVC and ABS pipes
- Requires careful measurement, including center-to-center spacing
- Pipe length must be trimmed correctly for proper installation
This is a practical pick if your system matches the 2-inch sizing requirement and you want a cleaner-looking termination point. Its main strength is simplicity: one low-profile kit that helps finish the venting job without adding visual clutter.
Premium Vertical Vent Choice – Rheem ProTech RTG20282 3" x 5" Concentric Kit
For shoppers comparing sidewall vent kits for tankless water heaters, this Rheem ProTech kit stands out as a vertical concentric vent option for compatible non-condensing gas units. It fits a 3 in. x 5 inch concentric vent setup and includes flashing, caps, and a storm collar, but you still need to add vent pipe to complete the installation.
Best For: Owners of compatible Rheem tankless gas non-condensing heaters who need a vertical concentric vent termination kit.
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:
- Requires additional vent pipe to finish installation
- Designed for vertical venting, not a general-purpose kit
- Compatibility is limited to specific gas non-condensing units
This kit makes sense when you want a brand-matched vertical vent termination with the essential finishing hardware included. It is less flexible than universal options, but it offers a clear path for the right Rheem setup.
Stainless Steel Vent Pipe Kit – GASLAND 3" Horizontal Vent Package
If you want sidewall vent kits for tankless water heaters with more complete pipe pieces included, this GASLAND stainless steel kit is a strong horizontal venting package. It is made for residential tankless heaters with a 3-inch exhaust port and includes a termination hood, 90-degree elbow, vent pipe sections, wall thimble, and gear clamps for a build-out that can be assembled to suit your needs.
Best For: Buyers who need a 3-inch stainless steel horizontal vent kit with multiple included components.
Pros:
- Includes termination hood, elbow, vent pipes, wall thimble, and clamps
- Made from T304 stainless steel for corrosion and temperature resistance
- Detachable design can be assembled in lengths to suit the installation
- Compatible with many GASLAND tankless water heater models
Cons:
- Requires a 3-inch diameter exhaust port
- Compatibility is narrower for buyers outside the listed models
- Length planning is still needed despite the modular design
This is the most fully featured option in the group if you already know you need a 3-inch horizontal venting setup. The stainless construction and included parts make it appealing for buyers who want a more complete kit rather than a simple termination cap.
Compact Wall Kit for 2-In. Vent Runs – Rheem ProTech Horizontal Vent Cone Termination Kit
If you need sidewall vent kits for tankless water heaters and are working with a 2 in. x 6 in. wall, this Rheem ProTech termination kit is built for a clean, straightforward install. It uses OEM factory-authorized parts, stainless steel construction, and an exclusive Snap-Lock design for a leak-free connection, making it a practical fit for non-condensing tankless setups.
Best For: Homeowners or installers needing a compact 2 in. wall termination kit for a non-condensing Rheem tankless unit.
Pros:
- Exclusive Snap-Lock design helps support a leak-free connection.
- Rugged stainless steel construction adds durability.
- Includes OEM genuine factory-authorized parts.
- Designed for 2 in. x 6 in. wall applications.
Cons:
- Made for non-condensing water heaters only.
- Wall-size compatibility is narrower than some alternatives.
This is a focused, no-frills vent solution for the right Rheem system and wall depth. If your installation matches the size and unit type, it offers a durable OEM path without unnecessary extras.
Adjustable 3 x 5 Wall Vent Kit – Rheem RTG20280-1 ProTech Horizontal Vent Termination Kit
For sidewall vent kits for tankless water heaters that need more wall-depth flexibility, this Rheem RTG20280-1 kit is built around a 3″ x 5″ horizontal vent termination and can extend to fit walls up to 10 inches thick. It uses stainless steel components, includes a 12-inch wall plate and mounting screws, and adds a 94-degree elbow to help with the venting layout.
Best For: Installations needing an adjustable-through-the-wall vent kit for a compatible Rheem non-condensing gas tankless heater.
Pros:
- Adjustable for wall thicknesses up to 10 inches.
- Includes a 12-inch wall plate and mounting screws.
- Stainless steel construction supports durability and corrosion resistance.
- 94-degree elbow is included for venting configuration.
Cons:
- Designed specifically for Rheem EcoSense mid-efficiency indoor direct vent units.
- Not a universal fit for all tankless water heaters.
This kit stands out when wall depth and installation hardware matter as much as the vent itself. If your heater matches the intended application, it gives you a more adaptable through-the-wall solution than fixed-depth kits.
Low-Profile 2-In. Wall Vent Kit – Rheem ProTech Horizontal Vent-Cone Termination Kit
If you want sidewall vent kits for tankless water heaters with a lower-profile termination, this Rheem ProTech option is built for 2 in. x 10 in. walls and supports up to 12-inch wall depths. It includes a 90-degree elbow, low-profile cone termination, trim ring, and screws, all in Class A stainless steel venting for compatible mid-efficiency units.
Best For: Buyers who want a low-profile termination kit for a compatible Rheem non-condensing tankless system and deeper wall run.
Pros:
- Low-profile cone termination helps keep the exterior look compact.
- Includes elbow, trim ring, and screws for installation.
- Fits walls up to 12 inches thick.
- Class A stainless steel venting is used for mid-efficiency units.
Cons:
- Not compatible with current Rheem venting supplied by Metal Fab.
- Built for specific non-condensing Rheem applications.
This kit makes sense when you need a deeper-wall solution without a bulky exterior termination. Just confirm compatibility before buying, since the notes call out a specific venting limitation.
How We Picked the Best Sidewall Vent Kits for Tankless Water Heaters
We focused on Sidewall Vent Kits for Tankless Water Heaters that match the most common installation needs: 2-inch and 3-inch venting, horizontal or vertical termination, and compatibility with leading brands such as Rheem, Rinnai, Navien, and A. O. Smith. We also looked at material durability, wall-depth coverage, and whether the kit is designed for condensing or non-condensing units.
Quick Comparison
The selection splits into two main groups. Smaller 2-inch horizontal termination kits are typically used with certain high-efficiency or non-condensing systems, while 3-inch x 5-inch stainless options are more common on non-condensing tankless models. Wall depth matters too: some kits are made for standard exterior walls, while others are sized for thicker walls or longer penetrations.
Key Buying Factors for Sidewall Vent Kits for Tankless Water Heaters
Heater Type and Venting Design
Start with the manufacturer’s venting requirements. Condensing and non-condensing units often use different vent materials, termination styles, and clearances. Never assume a vent kit is universal just because the pipe diameter looks similar.
Pipe Size and Kit Dimensions
Match the vent diameter precisely and confirm the wall-cone or termination length fits your installation depth. A kit that is too short can compromise the install, while one that is too long may require extra modification.
Material and Corrosion Resistance
Stainless steel is a strong choice for durability, especially in systems exposed to moisture and exhaust byproducts. For outdoor termination points, look for solid construction and weather-resistant components.
Installation Requirements
Check whether screws, elbows, cones, or pipe sections are included. A more complete kit can simplify installation, but only if the parts align with your heater’s venting instructions.
Who Should Buy Which Sidewall Vent Kits for Tankless Water Heaters?
If you have a Rinnai, Rheem, Navien, or similar tankless unit, choose the kit that matches the exact vent spec in the manual first, then narrow by wall thickness and material. Homeowners replacing an existing termination should prioritize exact size and form factor. Contractors and DIYers working on new installs should favor kits with clear compatibility and enough hardware to reduce trips for extra parts.
For most buyers, the safest pick is the kit that best matches the heater’s approved vent configuration rather than the one with the widest compatibility claim. When in doubt, verify the model number and local code requirements before buying.
