Solar Energy Manager, Recorder,
and Differential Controller

Download User's  Manual (PDF)

Thermo Alert monitors fresh produce or frozen food temperatures of a refrigerated  trailer. It has two independent sensors, that measure the top and bottom temperatures within the refrigerated chamber.  This dual-channel measurement provides high system reliability and accurate temperature monitoring. Air temperatures on the cold room floor tend to be colder and heavier. To account for this, the bottom sensor sets the lower limit alarm, which leaves the higher temperatures at the higher location to activate the upper limit. When either of these temperatures exceeds their limits, a visual (LED light) alarms the off limits conditions.


NOTE: The information presented in this page is for guidance only - no part of this may be used for any agreement, whether express or implied, or to form any contract. THERMO TECHNOLOGIES reserves the right to change specifications and prices without prior notice.


Solar History
The SMT 400 has an internal reusable memory which stores up to nine months of solar history (Collector, Tank temperatures and solar energy gain). A sample is taken every 10 minutes from each of these readings. These are then displayed in graphical form, thereby representing the system performance. The unit also records daily readings for the last 8 weeks, which are also plotted. In addition, it shows the total monthly energy for the last 6 months in the form of a histogram.


  • Precise digital differential controller for efficient heat collection
  • Bar Graph display of collector (manifold) temperature
  • Adjustable Delta T (DT) differential from 3-10oC
  • Digital display of collector (manifold) temperature
  • Bar Graph display of instantaneous power collected in kW, with auto-adjusting scale
  • Anti-frost thermostat for system protection Digital display of return (system) temperature24-hr clock Maximum system temperature thermostat Digital display of Tank 1 and Tank 2 temperatures
  • Two presentable divert temperatures providing a three-user zone system
  • Daily maximum / minimum temperature recorder for all its sensors Digital display of daily collected energy in kilo-calories Pump control matrix providing total user versatility Two independent time-thermostats for heat boosting Graphical display of collector and tank temperatures as well as the energy gain for the current and the previous day, based on an average reading taken every 10 minutes Graphical display of collector daily maximum temperatures and total daily energy gain for the last 8 weeks Status screen for indication of the current state of inputs and outputs of the collector Manual override of outputs for system testing Alarm indicator for warning in case of sensor failure or over-temperature Plug-removable controller for ease of installation
  • Plug-in sensors for ease of installation
  • Complies with EU EMC Directive 89/336/EEC


  • The SMT 400 is supplied with three sensors (Collector, Return, Tank)
  • If longer cables are needed, sensors are available with extended cable lengths
  • Alternatively, sensor extenders are available in a variety of lengths. If the sensors need to be extended, but factory-made extenders are not available, they can be extended using a suitable 4 core or 3 core cable

Three temperature sensors are included in a standard package. Tank and return sensors are supplied with 15 feet outdoor cable; collector sensor is 45 feet long. If required, sensor extenders are available. If sensors need to be extended but factory-made extenders are not available, they can be extended using a suitable four core cable.

Power Connection

  • P1 - Hot Water Pump 1P2 - Hot Water Pump 2P3 - Hot Water Pump 3A1 - Auxiliary Heater 1A2 - Auxiliary Heater 2This device should be properly grounded. Flexible wires simplify connection to the terminals. All connections should be secure and adequately tightened. It is good practice to keep mains cables away from sensor cables and other low voltage signal cables.AUX1 + AUX2 : MAX 3.5A (400W)PUMP1 + PUMP2 + PUMP3 : MAX 2.0A (250W)TOTAL LOAD : 5.5A(750W)
  • If the Auxiliary outputs are being used to drive a water heater element, then a mains contractor (Relay) should be used as illustrated

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