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1.00 LBS
Calculated at checkout

Product Description

ThermokLogger-4A Module

Off Grid Options presents the ThermokLogger-4A - an affordable and easy-to-use differential temperature controller for solar heating systems. It is a four channel 10K thermistor display and data logger with programmable solid state relay outputs.

The ThermokLogger-4A records directly to an included Secure Digital (SD™) card to provide convenient data downloads. To use the recorded data, simply insert the SD™ card into a card reader attached to a USB port on your computer (Windows, Macintosh and Linux).

Provided with four #6-32 machine screws and KL nuts. Packaged in pink anti-static bubble bag. No accessories provided.


  • 4 x thermistor Inputs (0 to 5 volt)
  • 1 x counter input (0 to 5 volt)
  • 2 x relay outputs (~5 amps DC)
  • Screw terminal and RJ-45 sensor inputs
  • Secure Digital (SD™) card, 512 megabyte, industrial, -40°C to 85°C


Solar Hot Water Diagram


Live Internet Data

Through APRS World, LLC, Off Grid Options offers World Data service free for our customers. Using an optional internet gateway module, our products can send live data to our hosted data service. Using your web browser you can view live and historical performance data and graphs. This allows your customer to see how their system is performing and allows you to troubleshoot the system without getting in your truck.


Technical Specifications

Measurement Inputs

  • Four 10K Thermistor: Typically measure -40°C to 150°C (-40°F to 302°F), screw terminals and RJ-45 wired in parallel
  • Pulse Counter: Screw terminals

User Interface

  • 16x2 Character LCD, backlit
  • Three push buttons
  • Temperatures update once per second
  • Relay / alarm status visible


  • Logs to Secure Digital™ or Multi Media Card™
  • Date and time stamped measurements
  • Data files in Comma Separated Vertical (CSV)
  • One data file per day
  • Includes 2 gigabyte SecureDigital™ card
  • Supports 2 gigabyte or smaller cards


  • 8 to 32 volts DC: 2.1 mm x 5.5 mm coaxial connector or 2 position screw terminal
  • Requires external power

Relay / Alarm Outputs

  • 2 x DC relay, solid state, 6 amps @ 39 volts DC max
  • Independently programmable for:
        Differential Control
        On above temperature set point
        Off above temperature set point
        Always On
        Always Off

RS-232 Communications

  • ASCII or binary data, selectable
  • Screw terminal, four position
  • Data compatible with our World Data Internet service
  • 9600 to 57600 baud
  • Can enable / disable Morningstar Tri-Star based on temperature
  • Modbus RTU Support


  • Mounts in double gang electrical box or panel
  • 36.8 mm (1.45 in) deep



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