State Water Heaters 100384259 Tankless Gas Water Heater 199K Btu

Product Description

The STATE WATER HEATERS 100384259 is the STM-199X3 ADAPT SC Ultra-Low NOx condensing tankless natural gas water heater rated at 199,000 BTU/h with a maximum flow rate of 10.5 GPM. It uses a modulating burner and condensing heat exchanger to deliver on-demand hot water at high efficiency, with a Uniform Energy Factor (UEF) of 0.95. Built-in X3 Scale Prevention Technology actively protects the heat exchanger from mineral build-up, extending service life by up to 300 percent compared to an unprotected unit. A built-in control display lets technicians check operating status, error codes, and temperature settings without additional tools. Licensed plumbers and gas technicians handle installation in residential and light commercial settings.

The STM-199X3 is designed for residential applications where high-demand, on-demand hot water is required. It installs indoors or outdoors, giving contractors flexibility across a wide range of job site conditions. PVC venting is supported at 2 inches up to 50 feet or 3 inches up to 150 feet, reducing material cost on many residential installs. For larger properties or multi-unit facilities, up to 12 identical units can be cascaded together using the included cable, scaling output without a storage tank system. An outdoor vent cap kit is sold separately for exterior installations.

Key Features

• 199,000 BTU/h input rating with 10.5 GPM maximum flow rate for high-demand residential supply
• Integrated X3 Scale Prevention Technology protects the heat exchanger and extends service life up to 300 percent longer than unprotected units
• Energy Star certified with a UEF of 0.95, qualifying for applicable efficiency incentives
• Ultra-Low NOx compliant for installation in air-quality-regulated regions
• PVC venting flexibility: 2-inch pipe up to 50 feet or 3-inch pipe up to 150 feet
• Cascade-ready for up to 12 units with included interconnect cable
• Built-in control display for status monitoring, error code retrieval, and setpoint adjustment

Compatibility

Designed as an OEM tankless condensing natural gas water heater for residential indoor and outdoor installations requiring high-capacity on-demand hot water delivery.

Installation Notes

Installation must be performed by a licensed plumber or gas technician in accordance with local plumbing codes, the International Fuel Gas Code (IFGC), and the manufacturer's installation manual. Shut off the gas supply and cold water inlet before beginning any connections or service work. PVC vent materials and outdoor kit compatibility should be confirmed before rough-in. Do not operate the unit without verifying proper gas type, supply pressure, and venting configuration.

Technical Specifications

• Input Capacity: 199,000 BTU/h
• Maximum Flow Rate: 10.5 GPM
• Fuel Type: Natural Gas
• Uniform Energy Factor (UEF): 0.95
• NOx Rating: Ultra-Low NOx
• Venting: PVC, 2 inches up to 50 feet or 3 inches up to 150 feet
• Installation Location: Indoor or Outdoor (outdoor kit sold separately)
• Cascade Capacity: Up to 12 units
• Certification: Energy Star
• Warranty: 15 Year

Standard Information

• Brand: STATE WATER HEATERS
• Manufacturer Part Number: 100384259