SC-20D

Din rail differential temperature controller with two sensors.

Universal temperature controller (solar collector, fireplace, circulating pumps, heater + fan control).

Controller designed to temperature control in solar collector's installations. Device controls collector pump [output1] and additional source of heat (cauldron, heater) [output2]. Second source is switched-on on a cloudy days, when energy from collectors is low and it is essential to heat-up the boiler from another source. Additional output [output2] can be also used to domestic hot water circulating pump or valve control.

  • TH-35 DIN rail mounting in distribution box

  • 3 temperature thresholds: directive + 2 alarm

  • high and low temperature alarm signalled by relay output and buzzer

  • 2 relay outputs: main 20A and 8A alarm

  • 2 NTC sensors included

  • Collector pump and the second source of heat control

  • Domestic hot water pump control

  • Boiler protection against freezing and overheating

  • Measurement and setting with 0,1 °C accuracy

  • Displaying T1 and T2 alternately

  • Sound signaller

  • 2 stainless steel temperature probes included

Principle of operation: 

Controller activates collector's pump only after heating up the sensor, in other words after reaching difference between boiler's and collector's temperature [T2-T1]. Second output according to own heating system controls boiler's temperature [T1] and switches on additional devices: 
  • to protect boiler against freezing controller switches on additional source of heat, when the temperature falls below the set, for example 5 °C, 
  • to protect boiler against overheating controller switches off collector's pump, and switches on circulating pump or valve, when the temperature on the boiler increases, for example to 85 °C, 
  • in domestic hot water pump control function controller switches on pump, after heating up the water in the boiler to the set temperature, for example 40 °C, 
  • in reheating function, controller switches on the second source of heat, when the boiler does not reach, for example 30 °C during 4 hours. 
The value from the collector's and boiler's sensor is being displayed every 3 seconds. It is possible to set the controller to display only one reading. Built-in sound singaller indicating emergency states. Logical input acts as an alarm input, for example signalling system failure after STB temperature limiter activation. In case of failure the whole system will hangs up with a possibility of maintain the failure status, up till manual reset button.

Specifications:

Inputs:
boiler and collector sensors NTC 5kOhm at 25°C included
digital input
Measuring range:
-50...+150°C
Measuring accuracy:
+/-0,5°C
Sampling period:
330 ms
Display resolution:
0,1°C in whole range
Setting resolution:
0,1°C in whole range
Display:
LED, 4 digits, 11mm height with graphic icons
Control form:
ON-OFF with hysteresis
Outputs:
main: relay 20A 4,5kW, durability 100 thousands cycles
alarm: relay 8A 1,5kW, durability 100 thousands cycles
Functions:
 
  • 3 work modes: normal, differential, averaging
  • high and low temperature alarm signalled by sound and relay output
  • sensor failure and digital input activation sound signalling
 
Mounting:
DIN rail TH-35
Degree and protection class:
depends on used distribution box
Power supply:
230V~ +/-15% or or 24V~ or 12V=/~
Power consumption:
max 3 VA
Operation conditions:
-5...60°C; 0...85%RH (non-condensing)
Storage conditions:
-40...85°C; 0...85%RH (non-condensing)