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Tankless Water Heaters

Tankless water heaters deliver endless hot water with compact, energy-smart designs. Shop gas (natural gas or LP) and electric models from Rinnai, Rheem, Stiebel Eltron, Eemax, and Chronomite—plus venting, recirculation, controls, and repair parts to finish the job.

Shop by need

  • Fuel & power: Natural Gas and Propane; Electric 120V or 240V point-of-use and whole-home
  • Model type: Condensing and Non-condensing; Indoor or Outdoor; Combination units
  • Recirculation: built-in recirc pump models, add-on pumps, pump hardware, controllers, and WiFi control accessories
  • Venting: concentric and twin-pipe kits, terminations, pipe covers, and heater guards
  • Kits & parts: NG/LP conversion kits, descaler/flush kits, repair parts, cables, and accessories
  • Series callouts: Rinnai Sensei CX and Sensei RX series options
  • 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 - 223176PP - 12", 3"/5" Condensing Horizontal Termination Kit

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

    Rinnai's 12 inch horizontal termination kit finishes the route for your venting on a Rinnai tankless water heater. The 223176PP pipe is made specif...

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    $ 110.00 - $ 110.00
    $ 110.00
    $ 110.00 - $ 110.00
    $ 110.00
  • 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 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 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 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 Vertical Discharge Adapter 4" 224064 - - Water Heater Venting - Big Frog Supply

    Rinnai - 224064 - Vertical Discharge Adapter 4"

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

    Rinnai's 224064 4 inch vertical discharge adapter is perfect for your tankless water heaters. Actual product's color may vary from shown. This ve...

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    $ 44.00 - $ 44.00
    $ 44.00
    $ 44.00 - $ 44.00
    $ 44.00

  • Rinnai - CVENT2 - DiversiTech Concentric 2" Vent Termination

    Rinnai
    $ 50.02 - $ 50.02
    $ 50.02
    $ 50.02 - $ 50.02
    $ 50.02

    DiversiTech 2 Inch Concentric Vent Termination The DiversiTech Concentric 2" Vent makes it easier to have a two-pipe installation for high efficien...

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    $ 50.02 - $ 50.02
    $ 50.02
    $ 50.02 - $ 50.02
    $ 50.02
  • 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 Shingle Roof Flashing (6/12 to 12/12 pitch) 189951 - - Water Heater Venting - Big Frog Supply
    Sold out

    Rinnai - 189951 - Shingle Roof Flashing (6/12 to 12/12 pitch)

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

    Rinnai shingle roof flashing that is made of high quality plastic. It's meant for 6/12 to 12/12 pitch. SKU: 189951 Actual product's color may vary ...

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    $ 87.00 - $ 87.00
    $ 87.00
    $ 87.00 - $ 87.00
    $ 87.00
    Sold out
  • 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 Condensate Trap 222053 - - Water Heater Venting - Big Frog Supply
    Sold out

    Rinnai - 222053 - Condensate Trap

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

    Rinnai has made the best condensating trap for their line of tankless water heaters. The 222053 condesate trap works with all plastic and metal com...

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    $ 61.00 - $ 61.00
    $ 61.00
    $ 61.00 - $ 61.00
    $ 61.00
    Sold out
  • 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 - 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 - 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 - 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 - 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 - 229230NPP - 10 in. 2/4 Condensing 90 Degree Elbow for Tankless Water Heaters

    Rinnai
    $ 24.25 - $ 24.25
    $ 24.25
    $ 24.25 - $ 24.25
    $ 24.25

    2/4 Condensing Vent Pipe Extension 10 in For Sensei Models Product Weight: 0.57 Height: 5.9" Width: 4.33" Depth: 6.29" Refer to the R...

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    $ 24.25 - $ 24.25
    $ 24.25
    $ 24.25 - $ 24.25
    $ 24.25

Quick choosing guide

  1. Size by flow: estimate peak demand in GPM at your winter inlet temperature rise. Whole-home gas units often cover 5–11+ GPM; electric point-of-use fits sinks and small loads.
  2. Pick fuel & placement: Gas for highest flow; choose indoor with proper venting or outdoor where climate allows. Electric units need the correct amperage and breakers.
  3. Efficiency: select condensing for higher efficiency and cooler exhaust; plan condensate drain where required.
  4. Faster hot water: choose a model with a built-in recirc pump or add a recirc kit and controller.
  5. Complete the install: vent kit and terminations for gas models; isolation/service valves; pipe covers; WiFi or wall controllers. Use NG/LP conversion kits only as specified.
  6. Maintenance: add a descaler/flush kit and schedule periodic cleaning to protect the heat exchanger.

Pro tips: Size for the coldest inlet temperature, verify gas line BTU capacity and vent route for NG/LP models, or breaker/wire size for electric units. Install isolation valves for easy flushing, set recirc schedules to cut wait time, and winterize outdoor units where required.

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