Rinnai 21-Inch Non Condensing Horizontal Termination Diverter Kit

In this review the Rinnai 223187 21-Inch Non Condensing Horizontal Termination Diverter Kit is examined for installers and homeowners who need a neat, code-friendly way to route flue gas horizontally from compatible indoor Rinnai water heaters. The bottom line: this kit is best for professional installation where a compact concentric venting solution is required, because it pairs a 21-in termination pipe with a 90 degree elbow and a rubber wall plate to provide zero clearance to combustibles and a clean finished wall penetration.

Key Features

• 21-in termination pipe: Provides the required horizontal reach for installations where the vent exits through a wall, avoiding roof routing.
• 90 degree elbow: Allows a right-angle change of direction to align the vent with the heater outlet while keeping the exterior termination compact.
• Rubber wall plate: Creates a neat, weather-resistant finish at the wall penetration and helps seal around the concentric pipe.
• Concentric Nubbin system compatibility: Works with most indoor Rinnai water heaters to combine intake and exhaust in a single compact run for simpler layout.
• Zero clearance to combustibles: Lets installers position the vent close to framing and finishes where local code permits.
• Professional installation recommended: Ensures proper alignment, sealing, and code compliance for safe venting.

Who It's For

The kit is aimed at HVAC technicians and experienced plumbing professionals fitting indoor Rinnai water heaters that accept concentric venting, especially in retrofit or tight-space installations where a short horizontal termination is preferred. Its compact parts and zero-clearance rating make it suited to mechanical rooms and utility walls where space and clearance are constrained.

Homeowners doing DIY work should take caution: the product description and design assume knowledge of proper venting practice and local code. This kit is not compatible with Rinnai 98 series units that require separate intake and exhaust venting, so those owners should look for the appropriate dedicated vent parts instead.

Pros & Cons

Pros

• Compact kit with a 21-in termination and elbow simplifies short horizontal runs and reduces material needs.
• Concentric Nubbin compatibility combines intake and exhaust for a tidy single-penetration install.
• Rubber wall plate gives a finished appearance and helps weatherseal the exterior opening.
• Zero clearance to combustibles allows flexibility in tight installation spaces.

Cons

• Not suitable for the Rinnai 98 series, which requires separate intake and exhaust components.
• Designed for professional installation, so DIY installers may need to hire a pro to meet code and ensure safety.

Specifications

Brand	Rinnai
Model	223187
Termination pipe length	21 in
Elbow included	1 90 degree elbow
Wall finish	Rubber wall plate
Clearance	Zero clearance to combustibles
Installation	Professional installation recommended

Our Verdict

The Rinnai 223187 21-Inch Non Condensing Horizontal Termination Diverter Kit is a practical, value-minded choice for technicians installing compatible indoor Rinnai water heaters where a short, concentric horizontal termination is needed. Its included elbow, rubber wall plate, and zero-clearance rating make for a tidy, code-friendly termination when fitted by a professional.

Frequently Asked Questions

Is this kit compatible with all Rinnai indoor models?
It is compatible with most indoor Rinnai water heater models but not with the 98 series, which requires separate intake and exhaust venting.

Can I install this myself?
The manufacturer recommends professional installation to ensure proper vent alignment, sealing, and compliance with local codes.

Does the kit provide clearance to combustibles?
Yes, the kit is specified for zero clearance to combustibles, allowing close placement to framing and finishes where codes permit.