Takagi T-K4U-IN 190000 BTU Direct Vent Whole House Tankless Water Heater

- Item #: BCI2223787

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Natural Gas
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This product has additional required/recommended options. To configure, add to your cart.

  • Thermostat Recommended
  • Direct Vent Recommended
  • Covers Recommended
  • Recess Box Recommended

Featuring a power vented flue this tankless water heater uses sealed combustion and is fully modulated, making it perfect for domestic hot water systems. It can also be used with water storage tanks, recirculation systems, hydronic heating systems, radiant floor heating systems, and/or combined domestic & heating applications while complying with Ultra-Low NOx regulations, lead free standards, and being Energy Star® Qualified.


  • Energy Star Qualified
  • Overheat Cutoff Fuse and Built-in Freeze Protection
  • Efficient, Durable and Easy to Install
  • Stronger than Standard Copper and More Resilient Against Erosion
  • Complies with Lead Free Standards
  • Includes Built-in Temperature Controller and Diagnostics
  • 3 or 4 Inch Venting
  • Up to 8 Gallons Per Minute
  • Acceptable for up to 4 Showers
  • Electric Ignition

HRS35 copper is an alloy that is 99.5% pure copper with a .5% mixture of other elements, this alloy is much stronger and harder than the standard C1220, which is the copper. HRS35 has 8 times the tensile strength of standard copper

Energy Star is an international standard for energy efficient consumer products originated in the United States of America. It was created in 1992 by the Environmental Protection Agency and the Department of Energy. Devices carrying the Energy Star service mark, such as computer products and peripherals, kitchen appliances, buildings and other products, generally use 20%–30% less energy than required by federal standards.

Following the South Coast Air Quality Management District (AQMD), several other AQMDs have adopted regulations to require residential water heater (<75,000 Btu/hr heat input) NOx emission to be less than 10 nanograms per joule of heat output. The South Coast AQMD also requires that tankless water heaters to have NOx emission less than less than 14 nanograms per joule of heat output or less than or equal to 20 ppm (at 3% O2, dry).


  • 20.5 Inch Height
  • 13.8 Inch Width
  • 8.5 Inch Depth
  • Weight: 40 Pounds
  • Energy Factor: .82
  • BTU: 15,000-190,000
  • Gas and Water Connections: 3/4" NPT
  • Water Pressure: 15-150 PSI
  • 120V AC
  • Nominal Dimensions: 13-4/5" (W) x 8-1/2" (D) x 20-1/2" (H)

Why choose Takagi? Takagi produce some of the most highly efficient tankless water heaters in the industry. With a commitment to innovation and quality, they are constantly creating new technology to keep up with their customers’ ever-changing hot water needs. Takagi sets the bar with the most stringent of durability testing standards for all of our models. For 15 years, Takagi has provided the most eco-friendly, energy-efficient water heating solutions in North America.

Additional Takagi Links

Our SKU: Takagi T-K4U-IN

This product is listed under the following manufacturer number(s):

  • Takagi T-K4U-IN-NG
    Natural Gas

*Denotes a finish or option that has been discontinued

Takagi T-K4U-IN Product Specifications

Installation Sheet
Specification Sheet
Configuration Tankless Water Heater
Depth 8.5
Direct Vent Yes
Duct Size 3" Round, 4" Round
Electronic Ignition Type Yes
Energy Factor 0.82
Energy Star Yes
Fuel Type Natural Gas
Gas Connection 3/4"
Height 20.5
Indoor Approved Yes
Indoor Installation Yes
Low Lead Compliant Yes
Maximum Flow Rate 10
Maximum Gas Input 190000
Maximum Vent Length 100 ft, 70 ft
Minimum Flow Rate 0.4
NG Energy Factor 0.82
Natural Gas Input (Max) 190000
Natural Gas Input (Min) 15000
Natural Gas Manifold Pressure 3
Natural Gas Pressure (Max) 10.5
Outdoor Approved No
Outdoor Installation No
Plug In Yes
Power Supply AC 120V
Product Weight 37
Voltage 120
Water Connection 3/4"
Water Pressure (Max) 150
Width 13.8

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