ESR21 D Solar controller—Triac variable speed output

The ESR21-D, is as per ESR21-R3 but has a VSD output. In open loop solar systems, increases system efficiency and pump reliability by starting pump on high speed to increase starting ability and slows pump down to minimize mixing in the tank.

The ESR21-D is a differential control unit which has been consciously made easy to install and operate. Its wide range of controls makes it useful in a multitude of applications: with solar thermal systems for domestic water and swimming pools, water heater loading, ventilation control, burner requirements with a holding circuit, air flap control for earth collectors with a temperature window, etc.

• All of the switch-on and switch-off points can be set separately

• Clear display with icons for all of the values displayed

• Status display for immediate recognition of extraordinary conditions

• Solar start function

• Pump blockage if collector overheats

• Anti-freeze function

• Heat meter

• Speed control

• Use of 3 temperature sensors of types KTY (2 k?) or PT1000

• Overvoltage protection at all inputs

• Very easy to install and operate

• Min/Max thresholds -20 to 150deg.C

• Differential temperature 0 to 99deg.C

• Accuracy typ.+/-2%

• Operating voltage 230 V AC 50-60HZ

• Power Consumption max. 3VA

• Rated current load 1.5A resistive-inductive cos phi 0.6

• Transformer short circuit proof

• ESR21 Controller Manual