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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 - CVENT3 - DiversiTech Concentric 3" Vent Termination

    Rinnai
    $ 49.58 - $ 49.58
    $ 49.58
    $ 49.58 - $ 49.58
    $ 49.58

    Concentric 3" Vent Termination  The DiversiTech 3-inch Concentric Vent Kit is the solution for simplifying high-efficiency furnace installations. T...

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    $ 49.58 - $ 49.58
    $ 49.58
    $ 49.58 - $ 49.58
    $ 49.58

  • Rinnai - 103000078 - Natural Gas to LP Gas Conversion Kit for RU180i Tankless Water Heater

    Rinnai
    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00

    Quick-n Easy Gas Conversion Remove 3 screws, change the orifice, parameter, and apply the new data plate Model Compatibility Conversion NG LPG...

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    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00

  • Rinnai HVENT-2 DiversiTech Horizontal 2" Termination Vent

    Rinnai
    $ 34.97 - $ 34.97
    $ 34.97
    $ 34.97 - $ 34.97
    $ 34.97

    2 Inch Horizontal Vent Termination The DiversiTech HVENT-2 2-inch Horizontal Termination Kit is the premium solution for cleanly venting high-effic...

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    $ 34.97 - $ 34.97
    $ 34.97
    $ 34.97 - $ 34.97
    $ 34.97

  • 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...

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    $ 50.75 - $ 50.75
    $ 50.75
    $ 50.75 - $ 50.75
    $ 50.75

  • Rinnai - 105000250 - Sensei External Pump Harness

    Rinnai
    $ 15.00 - $ 15.00
    $ 15.00
    $ 15.00 - $ 15.00
    $ 15.00

    Rinnai Sensei Pump Harness External Recirculation Pump Wire Harness (Part Number 105000250) is the essential accessory you need when adding an exte...

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    $ 15.00 - $ 15.00
    $ 15.00
    $ 15.00 - $ 15.00
    $ 15.00
  • Rinnai - Rinnai Connect Cable MSB-M - - Water Heater Controllers - Big Frog Supply

    Rinnai - MSB-M - Connect Cable

    Rinnai
    $ 102.00 - $ 102.00
    $ 102.00
    $ 102.00 - $ 102.00
    $ 102.00

    Rinnai Connect Cable MSB-M for Rinnai tankless water heaters. 13.1 ft with terminal connectors.

    $ 102.00 - $ 102.00
    $ 102.00
    $ 102.00 - $ 102.00
    $ 102.00
  • Rinnai - Rinnai Shingle Roof Flashing (8/12 to 16/12 pitch) 189952 - - Water Heater Venting - Big Frog Supply - 2
    Sold out

    Rinnai - 189952 - Shingle Roof Flashing (8/12 to 16/12 pitch)

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

    Precisely engineered accessories can add even more reliability, convenience and flexibility to Rinnai Tankless Water Heaters. With Rinnai Common Ve...

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    $ 87.00 - $ 87.00
    $ 87.00
    $ 87.00 - $ 87.00
    $ 87.00
    Sold out

  • 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 - MCC-601-W - Commercial Temp Controller - White

    Rinnai
    $ 178.34 - $ 178.34
    $ 178.34
    $ 178.34 - $ 178.34
    $ 178.34

    The MCC-601-W is made from premium materials, this Item offers great function and value for your home. This fixture is part of Rinnai's decorativ...

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    $ 178.34 - $ 178.34
    $ 178.34
    $ 178.34 - $ 178.34
    $ 178.34

  • 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
  • Sold out

    Rinnai - 103000079 - Natural Gas to LP Gas Conversion Kit for RU180e Tankless Water Heater

    Rinnai
    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00

    Quick-n Easy Gas Conversion Remove 3 screws, change the orifice, parameter, and apply the new data plate Model Compatibility Conversion NG LPG...

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    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00
    Sold out

  • Rinnai 103000082 Natural Gas to LP Gas Conversion Kit for RU130i Tankless Water Heater

    Rinnai
    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00

    Quick-n Easy Gas Conversion For RU103i Tankless Water Heater Simply remove 3 screws, change the orifice, parameter, and apply the new data plate ...

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    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00

  • Rinnai - 103000081 - Natural Gas to LP Gas Conversion Kit for RU160e Tankless Water Heater

    Rinnai
    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00

    Quick-n Easy Gas Conversion Remove 3 screws, change the orifice, parameter, and apply the new data plate Model Compatibility Conv NG LPG Univ ...

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    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00
  • Rinnai - Rinnai Metal Pass Through Venting Plate 224097 - - Water Heater Venting - Big Frog Supply
    Sold out

    Rinnai - 224097 - Metal Pass Through Venting Plate

    Rinnai
    $ 32.50 - $ 32.50
    $ 32.50
    $ 32.50 - $ 32.50
    $ 32.50

    Rinnai has the best metal pass through plate for your venting needs. The Rinnai 224097 is suitable for use with plastic and metal components. Actua...

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    $ 32.50 - $ 32.50
    $ 32.50
    $ 32.50 - $ 32.50
    $ 32.50
    Sold out

  • Rinnai - 242141 - Flashing for Metal Roof - Plastic

    Rinnai
    $ 108.98 - $ 108.98
    $ 108.98
    $ 108.98 - $ 108.98
    $ 108.98

    Flashing for Metal Roof For metal roof installations. Zero clearance to combustibles. Material: Plastic UPC: 8713645120461 Height: 2.5" Width...

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    $ 108.98 - $ 108.98
    $ 108.98
    $ 108.98 - $ 108.98
    $ 108.98

  • Rinnai - HVENT-3 - DiversiTech Horizontal 3" Termination Vent

    Rinnai
    $ 34.97 - $ 34.97
    $ 34.97
    $ 34.97 - $ 34.97
    $ 34.97

    Horizontal 3" Termination Vent Horizontal vent kits for use in venting high efficiency fossil fuel appliances. The low profile kit hides the vent f...

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    $ 34.97 - $ 34.97
    $ 34.97
    $ 34.97 - $ 34.97
    $ 34.97
  • Sold out

    Rinnai - M120SN - M-Series Heat Only 120,000 BTU Condensing Boiler

    Rinnai
    $ 2,493.07 - $ 2,493.07
    $ 2,493.07
    $ 2,493.07 - $ 2,493.07
    $ 2,493.07

    Why the "M" Series? For maximum momentum. Using proven technology, these boilers are designed to keep your day going and your family happy. Stand...

    View full details
    $ 2,493.07 - $ 2,493.07
    $ 2,493.07
    $ 2,493.07 - $ 2,493.07
    $ 2,493.07
    Sold out
  • Sold out

    Rinnai - M090CN - M-Series Domestic Hot Water 5.1 GPH 90,000BTU Combi Condensing Boiler

    Rinnai
    $ 2,799.93 - $ 2,799.93
    $ 2,799.93
    $ 2,799.93 - $ 2,799.93
    $ 2,799.93

    Why the "M" Series? For maximum momentum. Using proven technology, these boilers are designed to keep your day going and your family happy. Stand...

    View full details
    $ 2,799.93 - $ 2,799.93
    $ 2,799.93
    $ 2,799.93 - $ 2,799.93
    $ 2,799.93
    Sold out
  • Rinnai - Rinnai All-Weather Wall Discharge 223159 - - Water Heater Venting - Big Frog Supply

    Rinnai - 223159 - All-Weather Wall Discharge

    Rinnai
    $ 79.99 - $ 79.99
    $ 79.99
    $ 79.99 - $ 79.99
    $ 79.99

    Rinnai's all-weather wall discharge 223159. Product color may vary from displayed image.

    $ 79.99 - $ 79.99
    $ 79.99
    $ 79.99 - $ 79.99
    $ 79.99

  • Rinnai V53DeN V Series High Efficiency Tankless Water Heater

    Rinnai
    $ 667.49 - $ 667.49
    $ 667.49
    $ 667.49 - $ 667.49
    $ 667.49

    Rinnai V53DeN High Efficiency Water Heater Experience the perfect combination of efficiency and value with the Rinnai V53DeN Non-Condensing Tankles...

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    $ 667.49 - $ 667.49
    $ 667.49
    $ 667.49 - $ 667.49
    $ 667.49

  • Rinnai - V53DeP - V Model Series High Efficiency Tankless Water Heater by Rinnai

    Rinnai
    $ 667.49 - $ 667.49
    $ 667.49
    $ 667.49 - $ 667.49
    $ 667.49

    Rinnai V53DeP Propane Tankless Water Heater The Rinnai V53DEP High Efficiency Outdoor Tankless Heater delivers the perfect blend of continuous hot ...

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    $ 667.49 - $ 667.49
    $ 667.49
    $ 667.49 - $ 667.49
    $ 667.49

  • Rinnai - 103000083 - Natural Gas to LP Gas Conversion Kit for RU130e Tankless Water Heater

    Rinnai
    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00

    Quick-n Easy Gas Conversion Remove 3 screws, change the orifice, parameter, and apply the new data plate Model Compatibility Conversion NG LPG...

    View full details
    $ 45.00 - $ 45.00
    $ 45.00
    $ 45.00 - $ 45.00
    $ 45.00
  • Sold out

    Rinnai - M160SN - M-Series Heat Only 160,000 BTU Condensing Boiler

    Rinnai
    $ 2,393.24 - $ 2,393.24
    $ 2,393.24
    $ 2,393.24 - $ 2,393.24
    $ 2,393.24

    Why the "M" Series? For maximum momentum. Using proven technology, these boilers are designed to keep your day going and your family happy. Stand...

    View full details
    $ 2,393.24 - $ 2,393.24
    $ 2,393.24
    $ 2,393.24 - $ 2,393.24
    $ 2,393.24
    Sold out

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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