Differential Temperature Controller DTLED-2

Differential Temperature Controller DTLED-2


This unit DTLED2 can be used to control the operation of circulation pump of a solar system based on temperature difference between solar (boiler, stove, etc.) and water tank. Also can control supplementary heating of water tank up to a preset temperature.

  • Frost and overheat protection of solar and tank.
  • Separate outputs for circulation pump and supplementary heater of up to 5A.
  • Monitors two temperatures.
  • Fast and easy programmable - 4 main settings and one user defined parameter.
  • Modes of operation - „Auto” /”Holiday” easily selectable by a slide switch at front panel.
  • „Eco function” – postponе the heater activation if solar is active (if “there is sun” the supplementary heater is switched off) – this mode can activated/deactivated by by user at any time.
  • 2 pcs. PTC temperature probe – silicon cable 0.3M –PTC 1k
  • 2 separate  Relay outputs for:
-        Р1 – SPDT (N.O. +N.C.) contact. Outputs “live” for pump or valve (on and off) control
-        Р2 – SPST (N.O) contact for activation of supplementary heater

  • LED display with 2 digits and 6 additional LEDs for indication.
  • Buttons – 1pcs.
  • Easy setup – each main setting can be selected among a set of fixed values.
  • Main parameters setting – selectable by changing jumper location:
-        maximal temperature in tank: +65; +75; +85 °C
-        frost protection of solar (forced activation of pump): -25; -10; +5 °C
-        minimal temperature of solar to enable circulation based on dT: +40; +50 °C

  • Setting of dT (differential temperature – solar to tank) by a knob – fine : from 3 to 25°C
  • Setting of tank temperature (supplementary heating) – using push button on front panel: starting +25°C up to maximal temperature allowed in 5°C step;
  • Manual test/activation of pump – holding the push button on front panel.
  • PWM output for speed regulation of appropriate pumps


  • Power supply 220V AC – internal and pump – term. 21 (Live in “L”) / 18 („N”-neutral)
  • Pump output (N.O) – term.  19 (Live output) / 17 („N”-Neutral)
  • Supplementary heater (N.O.)–  temr. 16 and 15  -5A max

* Additional external fuse should be connected to term.21 of up to 6A.

  • Sensors 

TS1 – term.5,6 –  tank temperature              TS2 – term 7,8 – solar temperature.
9,10 - PWM output

Technical sheet DTLED