DDT2 is a digital differential thermostat for solar water heating and other applications with one relay output and two sensors.

This product was revised in 2024. See pictures, available only with case (with silkscreen graphic).

Features: - Supports digital sensors (DS18B20) and thermistors (NTC10k) - Digital display with source and sink temperature - Adjustable delta T (∆T) differential - Adjustable minumum starting temperature and sufficient temperature to keep it running - Adjustable target point (storage tank) temperature - Adjustable sensors offset - Nighttime water storage tank cooling - 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

The controller measures two temperatures. In mode one; if first temperature rises above the 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 modes two/three; it will switch relay output on only if the sink temperature is below/above target temperature. When sink temperature rises/drops above the set point the controller will switch relay output off.

Note! Power supply operates on 230 V mains.

Available programmed and tested with plastic case (includes silkscreen), with partly assembled PCB (no terminal screw terminals, solder your own, pitch 5.08 mm) or with screw terminals, with or without waterproof sensors. All sensors comes in stainless steel tube with 2 meters of cable, outer diameter of 6mm. For more options, different cable length, contact us.

Requires two DS18B20 1-wire sensors or two NTC10k thermistors or a combination, one DS18B20 and one NTC10k.