Digital differential thermostat
DDT2 is a digital differential temperature controller for solar hot water systems and other applications with one relay output. It covers the most common hydravlic configuration with one heat source (thermal collector) and one heat sink (water tank).
The controller measures two temperatures. In mode one; if source (first) temperature rises above the sink (second) temperature the controller will switch relay output on and will switch it off when the sink temperature rises above the set target temperature or the sink temperature approaches source temperature. In mode two; it will switch relay output on only if the sink temperature is below target temperature. When sink temperature rises above the set point the controller will switch relay output off.
- Supports digital sensors (DS18B20) and thermistors (NTC10k)
- Digital display with source and sink temperature
- Adjustable delta T (∆T) differential
- Adjustable target point – storage tank – and minumum starting temperature
- Nighttime water storage tank cooling
- Adjustable sensor offset
- Running hours counter
- Manual override of output (for system testing)
- Indicator for warning in case of sensor failure
- Solar panel overheat protection
- Relay delay protection
- Integrated power supply
- Easy installation and configuration
Current EU version of a controller works on 230 V mains and has Celsius readout.
All controllers are supplied with a pair of waterproof temperature sensors soldered to 200mm long leads. These are DS18B20, NTC10k or a combination.
- Switching difference: 0.5 — 20.0 °C, step 0.5 °C
- Hysteresis: 1.0 — 19.0 °C, step 0.5 °C
- Measuring range: −28.0 — 99.5 °C
- Controller operating environment: 5 — 40 °C
- Accuracy: 0.5 °C
- Power supply input: 230 V AC
- Output switch: single pole relay
- Maximal current through relay: 3 A
- Software version: 1809
- Product sheet (pdf)
- User manual (pdf)
- Uporabniška navodila za digitalni diferenčni termostat (pdf)
Usage (hydravlic configurations)
Differential thermostat could be used as solar controller or as domestic hot water tank controller.
Technical support is available on mail support@[this domain].