Watts Tekmar Radiant Thermostat 519, One Stage Heat (Includes Slab Sensor 079)

Radiant Thermostat 519

The Radiant Thermostat 519 by Watts is designed to precisely regulate room and/or floor temperatures within hydronic heating zones, employing cutting-edge Pulse Width Modulation (PWM) technology. Featuring straightforward up and down buttons and a display with prominently sized fonts, this thermostat ensures ease of readability and operation. To safeguard against overheating and enhance comfort, it comes equipped with a Slab Sensor 079 for accurate floor temperature measurement. Installation is hassle-free, as it serves as a direct replacement for the tekmar Thermostat 509. Additionally, an optional Adaptor Plate 012 is available for installation onto a single gang electrical box.

Key Features:

  • Automatic heating cycle
  • Radiant floor heating functionality
  • Utilizes pulse width modulation for precise control
  • Regulates both floor and air temperatures
  • Displays outdoor and floor temperatures
  • Includes a convenient backlight for enhanced visibility
  • Offers freeze protection for added safety
  • Comes complete with a slab sensor 079 for comprehensive functionality


Agency Approvals Meets Class B: ICES & FCC Part 15
Ambient Conditions Indoor use only, 32 to 122 degrees F (0 to 50 degrees C), RH less than or equal to 90 percent non-condensing
Control Type Microprocessor control, this is not a safety (limit) control
Dimensions 3-11/16″ H x 3″ W x 15/16″ D (94 x 76 x 24 mm)
Enclosure Material White PVC plastic
Enclosure NEMA Rating NEMA 1
Power Supply 10 to 30 V (ac/dc), 50/60 Hz, 1.8 VA standby, 56 VA max fully loaded, Class 2
Relay 30 V (ac/dc) 2 A, Class 2 circuits
Sensor NTC thermistor, 10 k ohms at 77 degrees F (25 degrees C plus / minus 0.2 degrees C) Beta = 3892