Tekmar Controls 156 Control

The Tekmar Controls 156 is a versatile Difference Setpoint Control designed for high-efficiency heat transfer between a primary source and a storage tank. Operating on a 24Vac/dc power supply, this microprocessor-based controller utilizes two 10k sensors to monitor real-time temperature differentials (?T). When the source temperature exceeds the storage temperature by the user-defined setpoint, the internal 240V, 10A relay closes to activate an on/off pump control or valve. This logic is essential for optimizing solar thermal systems, wood-fired boiler loops, and indirect domestic hot water (DHW) tanks. The unit features a digital display that tracks relay run hours and Delta-T hours, aiding technicians in energy calculation and performance auditing. Designed for indoor installation, the 156 includes adjustable source minimum and storage maximum settings to protect equipment from low-grade heat cycles or overheating, ensuring the system only operates when thermal gain is viable.

Key Benefits

• Precise differential temperature control minimizes pump cycling and maximizes heat harvesting.
• Dual-power compatibility supports 24Vac or 24Vdc field applications for maximum flexibility.
• Integrated LCD provides clear diagnostics, including relay running hours and MIN/MAX temperature history.
• Robust 10A relay capacity is suitable for direct control of small pumps or as a pilot duty trigger for larger contactors.
• Compact NEMA 1 enclosure ensures a clean, professional finish on standard electrical boxes or wall mounts.

Common Questions

How do I resolve an "OPN" or "Short" sensor error?
An "OPN" error indicates an open circuit, while "Short" indicates a 0-ohm reading. Check the terminal connections for the source and storage sensors. Since the 156 uses 10k ohm NTC thermistors, verify resistance across the leads; at 77°F, you should read exactly 10,000 ohms. Replace the 071 sensors if readings are inconsistent.

Can this control be used for thermal shock protection?
Yes. By setting a source minimum temperature, you ensure the pump does not circulate cold water into a cast iron boiler, helping to maintain internal vessel temperatures above the condensing point during start-up.

What is the maximum distance for sensor wiring?
You can extend sensor leads up to 500 feet using 18 AWG shielded twisted pair wire. Keep sensor wiring away from high-voltage lines to prevent electromagnetic interference that could disrupt the differential setpoint accuracy.

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.