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Spec Sheet   Install Manual

With an enhanced combustion design, the Rinnai SENSEI Tankless Water Heater provides a better experience for both users and installers. Like all Rinnai Tankless Water Heaters, it's also vertically integrated. That means all key components are manufactured by Rinnai — to ensure Rinnai quality.

Condensing Technology for Colder Climates

The Rinnai SENSEI offers freeze protection down to -4o F (for outdoor units) or -22o F (for indoor units) through:

  • NEW integrated check valve that prevents backflow from outside cold air
  • NEW Fiber Mesh Premix Burner
  • Integrated logic to temporarily activate the unit in extreme cold climates

Most Flexible Venting in the Industry

The Rinnai® Sensei™ can go in an old condensing vent system for replacement if needed, but new installs can use smaller, lighter, less expensive concentric venting.

Now Including 2" Venting Options

Diameter Equivalent Length Termination
3" x 5" 150' (46m) Vertical or Horizontal
2" x 4" (New) 65' Vertical or Horizontal
  • Unit requires only a single penetration through the wall, reducing install time and costs
  • Simple positive-fit components offer a secure connection
  • Joint seals expand and contract with weather to prevent damage
  • Assembly and adjustment are easy

Twin Pipe and Room Air
Diameter Material Equivalent Length Termination
3" PP,PVC,CPVC 150' (46m) Vertical or Horizontal
2"(New) PP,PVC,CPVC 65' Vertical or Horizontal


Dimensions Product Width (inches): 14.76
Product Height (inches): 33.86
Product Depth (inches): 22.05
Mobile Home Certified No
Product Weight (lbs) 72.3
Wi-Fi Capable Yes
Energy Star Certified Yes
Circ-Logic Compatible (S/N - Production Date) Yes
Recirculation Capable Yes
Recirculation Pump No
Cold Water Inlet Connection 3/4" MNPT/19mm
Domestic Hot Water Temperature Range (Standard) (°F/°C) 98F-120F 37C-49C
Domestic Hot Water Temperature Range (Optional) (°F/°C) 98F-185F 37C-85C
Gas Supply Connection 3/4" MNPT 19mm
Gas Type Natural Gas
Hot Water Outlet Connection 3/4" MNPT 19mm
Isolation Valves Included Yes
Manufacturer Model Number REU-N3237WC-US-N
Maximum BTU 199,000 BTU/h
Minimum BTU 15,000 BTU
Maximum Altitude 10,200'
NOx Level 150 PSI 1035 KPa
Commercial Warranty (Years) Heat Exchanger: 8, Labor: 1, Parts: 5
Residential Warranty (Years) Heat Exchanger: 15, Labor: 1, Parts: 5

* It is recommended that a trained and qualified professional who has attended a Rinnai training class complete the installation. The warranty may be voided due to any improper installation.

— Installation and service must be performed by a licensed professional.


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How Tankless Water Heaters Work

Product Height
31.3 in / (795 mm)
Product Width
18.5 in / (470 mm)
Product Depth
11.45 in / (290 mm)
Product Weight
62 lb / (28 kg)
Shipping Depth (inches/mm)
33.1 in / (841 mm)
Shipping Height (inches/mm)
33.1 in / (841 mm)
Shipping Width (inches/mm)
21.7 in / (551 mm)
Shipping Weight (lbs/kg)
73 lb / (33 kg)

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