Tekmar Controls 518 Thermostat

The Tekmar 518 Thermostat is a professional-grade, non-programmable 24Vac one-stage heat thermostat designed specifically for precision in hydronic radiant floor heating systems. Engineered to replace the legacy 507 and 508 models, this unit utilizes advanced Pulse Width Modulation (PWM) technology to eliminate the temperature swings common with standard on/off controls, ensuring a stable thermal mass within the slab. The auxiliary sensor input offers versatile control logic, allowing for the connection of a 10k thermistor to monitor floor, outdoor, or remote room temperatures. With built-in freeze protection and an auto heating cycle, this thermostat maintains system integrity during extreme cold. The vertical mount interface features a large, backlit display and simple button navigation, making it a reliable choice for high-traffic or simplified mechanical room applications where consistent comfort and technical accuracy are the priority.

• Precision Temperature Control: Employs microprocessor PID logic and PWM to prevent overshoot in high-mass radiant systems.
• Versatile Sensing: Automatically detects remote room sensors, slab sensors, or outdoor sensors to customize the heat demand.
• Backwards Compatibility: Serves as a direct replacement for the Tekmar 507 and Tekmar 508, fitting the same footprint or using an optional 012 adapter plate for single-gang boxes.
• System Protection: Includes integrated freeze protection to safeguard piping if ambient temperatures drop significantly.

• How do I resolve an "OPN" error on the display? This typically indicates an open circuit on the auxiliary sensor input. Verify your terminal connections or disable the auxiliary sensor in the installer menu if not in use.
• Can this control a zone valve or a relay? Yes, the internal dry contact relay is rated for 2.0 Amps at 30VAC, making it suitable for driving zone valves or switching relays.
• Does it require a common wire? Yes, this is a hardwired 24V low voltage thermostat that requires a constant 24VAC (R and C) power supply for the display and microprocessor functions.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.