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Tankless Venting

Tankless install and vent kits to finish gas (NG/LP) and high-output electric water heaters cleanly and to spec. Shop concentric and twin-pipe venting, wall/roof terminations, thimbles and flashings, pipe covers, isolation/flush valves, and condensate parts—then match diameters and lengths to your model’s tables.

Shop by need

  • Concentric vent kits: coaxial intake/exhaust with horizontal or vertical terminations
  • Twin-pipe venting: separate intake and exhaust in PVC/CPVC/PP (per manual/code)
  • Terminations & adaptors: low-profile wall caps, roof cones, rain caps, conversion adaptors
  • Pass-through & sealing: wall thimbles, firestops, roof flashings, sealant and gaskets
  • Lengths & fittings: straight pipe, long/short-radius 45°/90° elbows, support clamps
  • Pipe covers & mounts: trim covers, brackets, stand-off kits, intake screens
  • Water/gas hook-up: isolation/flush valve sets, flexible gas connectors, shut-off valves
  • Condensate: traps, hose kits, pumps, and neutralizers for condensing units

Quick choosing guide

  1. Confirm model & type: indoor vs outdoor; condensing vs non-condensing. Use only vent materials approved by the manufacturer and local code (e.g., PVC/CPVC/PP for many condensing models; Category III stainless for some non-condensing).
  2. Pick vent style: Concentric simplifies wall/roof penetrations; twin-pipe is flexible for long runs or existing chases.
  3. Size the diameter: choose 2", 3", or 4" per the spec sheet. Calculate total equivalent length (add elbows) and stay within limits.
  4. Plan termination: horizontal or vertical, with code clearances to windows, doors, and grade. For condensing exhaust, pitch the vent back to the heater to drain condensate.
  5. Complete the kit: thimble/firestop, flashing, required adaptors, support hardware, pipe cover, and—on condensing models—condensate drain and neutralizer.
  6. Hook up water & gas: add isolation/flush valves, sediment/scale protection, a listed gas shut-off and connector, and a nearby outlet if the unit needs power.


  • Rinnai - Rinnai Universal Horizontal Termination Kit 11.5" 223181 - - Water Heater Venting - Big Frog Supply - 2
    Rinnai - Rinnai Universal Horizontal Termination Kit 11.5" 223181 - - Water Heater Venting - Big Frog Supply - 1

    Rinnai 223181 Non-Condensing Universal Horizontal Termination Kit 11.5"

    Rinnai
    $ 96.19 - $ 96.19
    $ 96.19
    $ 96.19 - $ 96.19
    $ 96.19

    Rinnai Universal Horizontal Termination Kit The Rinnai 223181 Non-Condensing Horizontal Termination Kit is an 11-1/2” universal venting solution th...

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    $ 96.19 - $ 96.19
    $ 96.19
    $ 96.19 - $ 96.19
    $ 96.19
  • Rinnai - Rinnai 21" Horizontal Termination Kit for Condensing Units 223177PP - - Water Heater Venting - Big Frog Supply

    Rinnai - 223177PP - 21" Horizontal Termination Kit for Condensing Units

    Rinnai
    $ 114.00 - $ 114.00
    $ 114.00
    $ 114.00 - $ 114.00
    $ 114.00

    Rinnai's 21 inch horizontal termination kit finishes the route for your venting on a Rinnai tankless water heater. The 223177PP pipe is made specif...

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    $ 114.00 - $ 114.00
    $ 114.00
    $ 114.00 - $ 114.00
    $ 114.00
  • Rinnai - Rinnai Vent Pipe Extension 39" for Condensing Units 224080PP - - Water Heater Venting - Big Frog Supply

    Rinnai - 224080PP - Vent Pipe Extension 39" for Condensing Units

    Rinnai
    $ 58.00 - $ 58.00
    $ 58.00
    $ 58.00 - $ 58.00
    $ 58.00

    Rinnai's 39 inch vent pipe extension helps route venting for your Rinnai tankless water heater. The 224080PP pipe is made specifically for Condensi...

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    $ 58.00 - $ 58.00
    $ 58.00
    $ 58.00 - $ 58.00
    $ 58.00
  • Rinnai - Rinnai Universal Horizontal Termination Kit 21" 223182 - - Water Heater Venting - Big Frog Supply

    Rinnai - 223182 - Universal Horizontal Termination Kit 21"

    Rinnai
    $ 114.99 - $ 114.99
    $ 114.99
    $ 114.99 - $ 114.99
    $ 114.99

    Long termination kit for Rinnai tankless water heater venting in the shape of an L to go outside of side wall. Inner exhaust material is aluminum a...

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    $ 114.99 - $ 114.99
    $ 114.99
    $ 114.99 - $ 114.99
    $ 114.99
  • Rinnai - Rinnai Vent Pipe Extension 39" 224053 - - Water Heater Venting - Big Frog Supply

    Rinnai - 224053 - Vent Pipe Extension 39"

    Rinnai
    $ 78.00 - $ 78.00
    $ 78.00
    $ 78.00 - $ 78.00
    $ 78.00

    39" vent pipe extension for your Rinnai tankless water heater venting. Inner exhaust material is aluminum and outer intake material is plastic. Pa...

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    $ 78.00 - $ 78.00
    $ 78.00
    $ 78.00 - $ 78.00
    $ 78.00
  • Rinnai - Rinnai 38" Roof Discharge for Condensing Units 184162PP - - Water Heater Venting - Big Frog Supply

    Rinnai - 184162PP - 38" Roof Discharge for Condensing Units

    Rinnai
    $ 110.00 - $ 110.00
    $ 110.00
    $ 110.00 - $ 110.00
    $ 110.00

    Rinnai roof discharge 38" for condensing ultra series tankless water heaters. SKU: 184162PP Color of product may differ from image. This Venting ...

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    $ 110.00 - $ 110.00
    $ 110.00
    $ 110.00 - $ 110.00
    $ 110.00
  • Rinnai - Rinnai Vent Pipe Extension 19.5" for Condensing Units 224079PP - - Water Heater Venting - Big Frog Supply

    Rinnai - 224079PP - Vent Pipe Extension 19.5" for Condensing Units

    Rinnai
    $ 49.00 - $ 49.00
    $ 49.00
    $ 49.00 - $ 49.00
    $ 49.00

    Rinnai's 19.5 inch vent pipe extension helps route venting for your Rinnai tankless water heater. The 224079PP pipe is made specifically for Conden...

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    $ 49.00 - $ 49.00
    $ 49.00
    $ 49.00 - $ 49.00
    $ 49.00
  • Rinnai - Rinnai Vent Pipe Extension 10" 224051 - - Water Heater Venting - Big Frog Supply

    Rinnai - 224051 - Vent Pipe Extension 10"

    Rinnai
    $ 50.00 - $ 50.00
    $ 50.00
    $ 50.00 - $ 50.00
    $ 50.00

    10" vent pipe extension for your Rinnai tankless water heater venting. Inner exhaust material is aluminum and outer intake material is plastic. Pa...

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    $ 50.00 - $ 50.00
    $ 50.00
    $ 50.00 - $ 50.00
    $ 50.00
  • Rinnai - Rinnai Vent Pipe Extension 10" for Condensing Units 224087PP - - Water Heater Venting - Big Frog Supply

    Rinnai - 224087PP - 10" Metal Pass Through Condensing Venting Plate

    Rinnai
    $ 39.00 - $ 39.00
    $ 39.00
    $ 39.00 - $ 39.00
    $ 39.00

    Rinnai's 10 inch vent pipe extension helps route venting for your Rinnai tankless water heater. The 224087PP pipe is made specifically for Condensi...

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    $ 39.00 - $ 39.00
    $ 39.00
    $ 39.00 - $ 39.00
    $ 39.00
  • Rinnai - Rinnai 90 Degree Vent Pipe Elbow for Condensing Units 224078PP - - Water Heater Venting - Big Frog Supply

    Rinnai - 224078PP - 90 Degree Vent Pipe Elbow for Condensing Units

    Rinnai
    $ 44.00 - $ 44.00
    $ 44.00
    $ 44.00 - $ 44.00
    $ 44.00

    Rinnai's 90 degree elbow vent pipe helps route venting for your Rinnai tankless water heater. The 224078PP pipe is made specifically for Condensing...

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    $ 44.00 - $ 44.00
    $ 44.00
    $ 44.00 - $ 44.00
    $ 44.00
  • Rinnai - Rinnai 45 Degree Vent Pipe Elbow for CONDENSING Units 224077PP - - Water Heater Venting - Big Frog Supply

    Rinnai - 224077PP - 45 Degree Vent Pipe Elbow for CONDENSING Units

    Rinnai
    $ 61.00 - $ 61.00
    $ 61.00
    $ 61.00 - $ 61.00
    $ 61.00

    Rinnai's 45 degree elbow vent pipe helps route venting for your Rinnai tankless water heater. This 224077PP pipe is made specifically for Condensin...

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    $ 61.00 - $ 61.00
    $ 61.00
    $ 61.00 - $ 61.00
    $ 61.00
  • Rinnai - Rinnai 18" Roof Discharge Terminal 184118S - - Water Heater Venting - Big Frog Supply

    Rinnai - 184118S - 18" (above roof) Roof Discharge Terminal

    Rinnai
    $ 115.00 - $ 115.00
    $ 115.00
    $ 115.00 - $ 115.00
    $ 115.00

    Rinnai roof discharge 18" for non-condensing ultra series tankless water heaters. SKU: 184118S Color of product may differ from image. This ventin...

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    $ 115.00 - $ 115.00
    $ 115.00
    $ 115.00 - $ 115.00
    $ 115.00
  • Rinnai - Rinnai 90 Degree Elbow 224063 - - Water Heater Venting - Big Frog Supply

    Rinnai - 224063 - 90 Degree Elbow

    Rinnai
    $ 63.00 - $ 63.00
    $ 63.00
    $ 63.00 - $ 63.00
    $ 63.00

    This 90 degree elbow is for non-condensing (luxury and value series) Rinnai tankless water heaters. Rinnai 224063. Product color may differ from im...

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    $ 63.00 - $ 63.00
    $ 63.00
    $ 63.00 - $ 63.00
    $ 63.00
  • Rinnai - Rinnai Vent Pipe Extension 19.5" 224052 - - Water Heater Venting - Big Frog Supply

    Rinnai - 224052 - Vent Pipe Extension 19.5"

    Rinnai
    $ 71.00 - $ 71.00
    $ 71.00
    $ 71.00 - $ 71.00
    $ 71.00

    19.5" vent pipe extension for your Rinnai tankless water heater venting. Inner exhaust material is aluminum and outer intake material is plastic. ...

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    $ 71.00 - $ 71.00
    $ 71.00
    $ 71.00 - $ 71.00
    $ 71.00

  • Rinnai - 224356NPP - 2inch / 4 inch Condensing Roof Discharge Termination 20 in. Above Roof

    Rinnai
    $ 68.70 - $ 68.70
    $ 68.70
    $ 68.70 - $ 68.70
    $ 68.70

    For use with the following models: RU199i RU180i RU160i RU130i RUR199i RUR160i CU199i CU160i Material of Inner/Exhaust - Polypropylene Mater...

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    $ 68.70 - $ 68.70
    $ 68.70
    $ 68.70 - $ 68.70
    $ 68.70
  • Rinnai - Rinnai 45 Degree Elbows For Venting NON CONDENSING (2 Pack) 224050 - - Water Heater Venting - Big Frog Supply

    Rinnai - 224050 - 45 Degree Elbows For Venting NON CONDENSING (2 Pack)

    Rinnai
    $ 87.00 - $ 87.00
    $ 87.00
    $ 87.00 - $ 87.00
    $ 87.00

    45 degree elbows for your Rinnai tankless water heater venting. Inner exhaust material is aluminum and outer intake material is plastic. Part Numb...

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    $ 87.00 - $ 87.00
    $ 87.00
    $ 87.00 - $ 87.00
    $ 87.00

  • Rinnai - 229310NPP - 2inch / 4 inch Condensing Vent Pipe Extension, 39 Inches

    Rinnai
    $ 49.99 - $ 49.99
    $ 49.99
    $ 49.99 - $ 49.99
    $ 49.99

    For use with the following models: RU199i RU180i RU160i RU130i RUR199i RUR160i CU199i CU160i Material of Inner/Exhaust - Polypropylene Mater...

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    $ 49.99 - $ 49.99
    $ 49.99
    $ 49.99 - $ 49.99
    $ 49.99

  • Rinnai - 229308NPP - 2 in. / 4 in. x 10 in. Plastic Condensing Vent Pipe Extension Kit

    Rinnai
    $ 33.79 - $ 33.79
    $ 33.79
    $ 33.79 - $ 33.79
    $ 33.79

    Concentric venting allows for secure connection 2 in. / 4 in. condensing vent pipe extension 10 in For use with Sensei Se+ tankless water heaters ...

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    $ 33.79 - $ 33.79
    $ 33.79
    $ 33.79 - $ 33.79
    $ 33.79

  • Rinnai - 229309NPP - 2 in. / 4 in. x 19.5in. Plastic Condensing Vent Pipe Extension Kit

    Rinnai
    $ 29.99 - $ 29.99
    $ 29.99
    $ 29.99 - $ 29.99
    $ 29.99

    Concentric venting allows for secure connection 2 in. / 4 in. condensing vent pipe extension 19.5 in For use with Sensei Se+ tankless water heater...

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    $ 29.99 - $ 29.99
    $ 29.99
    $ 29.99 - $ 29.99
    $ 29.99

  • Rinnai - 227412NPP - 2/4 Condensing Vertical Starter Adapter

    Rinnai
    $ 56.00 - $ 56.00
    $ 56.00
    $ 56.00 - $ 56.00
    $ 56.00

    Rinnai 2/4 Condensing Vertical Starter Adapter Weight: 1.39lbs Height: 5.63" Width: 5.71" Depth: 9.92"

    $ 56.00 - $ 56.00
    $ 56.00
    $ 56.00 - $ 56.00
    $ 56.00

  • Rinnai - 229013NPP - 2/4 21 Inch Condensing Horizontal Termination Kit

    Rinnai
    $ 81.00 - $ 81.00
    $ 81.00
    $ 81.00 - $ 81.00
    $ 81.00

    2 in. / 4 in. condensing horizontal termination kit 21 in. For use with Sensei Se+ tankless water heaters (condensing) and m-series boilers White ...

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    $ 81.00 - $ 81.00
    $ 81.00
    $ 81.00 - $ 81.00
    $ 81.00

  • Rinnai - 229012NPP - 12 Inch 2/4 Condensing Horizontal Termination Kit

    Rinnai
    $ 72.99 - $ 72.99
    $ 72.99
    $ 72.99 - $ 72.99
    $ 72.99

    2/4 Cond Horiz Termination Kit 12in Brand Model Compatibility SE+ Tankless Water Heaters and M-Series Boilers Diameter 4 in Lengt...

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    $ 72.99 - $ 72.99
    $ 72.99
    $ 72.99 - $ 72.99
    $ 72.99

  • Rinnai - 187595NPP - 2in x 2/4 Condensing Twin Pipe Adaptor

    Rinnai
    $ 92.00 - $ 92.00
    $ 92.00
    $ 92.00 - $ 92.00
    $ 92.00

    Features: Twin pipe adapter 2 in. x 2/4 Dimensions: 5.67 in. x 9.92 in. x 14.4 in. Water heater accessory For use with SENSEI SE+ tankless water h...

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    $ 92.00 - $ 92.00
    $ 92.00
    $ 92.00 - $ 92.00
    $ 92.00

  • Rinnai - 229205NPP - Condensing 2/4 45 Degree Elbow (2 Pack) for Tankless Water Heaters 229205NPP

    Rinnai
    $ 50.75 - $ 50.75
    $ 50.75
    $ 50.75 - $ 50.75
    $ 50.75

    For use with Sensei Se+ tankless water heaters (condensing) and m-series boilers. Refer to the Rinnai Water Heater Installation and Operation man...

    View full details
    $ 50.75 - $ 50.75
    $ 50.75
    $ 50.75 - $ 50.75
    $ 50.75

Pro tips: Dry-fit and measure twice, support vents per the manual, and use the manufacturer’s approved cement or gasketed joints (no sealant on gasketed lock-rings). Maintain clearances, neutralize condensate, and keep a printout of your vent length calc with the install. After start-up, check for leaks, verify combustion settings, and run a full hot-water draw. Questions? Tell us model, fuel, vent path, and pipe size—we’ll recommend the right kit.

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