Temperature differential switch

A temperature difference switch is also called Delta-T control. It measures two separate temperatures
In a solar boiler system, the circulation pump only runs when it produces energy: i.e. when the temperature in the collector is higher than that in the storage tank.
To monitor energy yield, switching times and measured temperatures are stored in memory.
The temperature difference switch is also suitable for other climate-related applications, such as ventilation. It includes 2 relays for switching pumps, fans or valves on and off.

Menu-controlled temperature differential switch

In a simple way -using the 4 buttons- you can enter the following operating parameters:
•    Temperature differential (delta T)
•    Switch hysteresis (in ºC)
•    Minimum collector temperature
•    Maximum cylinder temperature

Memory and data logging

The set values remain in memory if a power failure occurs. Upon return of mains power, the temperature difference switch immediately operates again.
The pump running times and the lowest + highest measured temperatures are stored in memory. This occurs when switching from manual (programming mode) to automatic mode. Operating parameters are stored every 3 hours in automatic mode.

Status check on the display

All measured values (collector temperature, boiler temperature and temperature difference), as well as the settings entered (difference hysteresis, min/max values and run times) can be called up on the display. As soon as you press a button, the display lighting comes on (briefly).

Setting maximum storage temperature

To minimize scaling in the boiler, it is useful to set a maximum boiler temperature. When this temperature is reached, the second relay in the temperature difference switch can control a bypass valve (or other pump).
In case of malfunctions in the solar boiler system, you can manually activate both relays if required. The LED lights show whether the respective relay is switched on. In case of an interruption in the sensor wiring, both relays switch on to prevent overheating of the system.

Various solar boiler applications

The temperature differential switch is optimized for controlling a solar water heater installation. The temperature range goes up to +99 °C.
The temperature differential switch is suitable for a swimming pool and other solar water heater applications. For example, the minimum temperature limit in the heat source can be used in combination with the boiler of the central heating system. This avoids flue gas condensation on the boiler walls.
Relay output: two voltage-free changeover contacts, one for switching a circulation pump and the other for an alarm signal, auxiliary pump or valve.

Works with Pt1000 sensors

•    Attractive plastic housing, intended for wall mounting.
•    The device contains 2 switching contacts of 5 amps each.
•    Fault message in case of interrupted or short-circuited sensor.
•    Inputs only suitable for 2 Pt1000 sensors.
•    Optional sensors: 2 pieces IP68, Ø 6 mm, length 50 mm.
•    Sensor connection wires may be extended up to 50 m.

Temperature differential switch - data

•    Dimensions: 160 x 120 x 64 mm
•    Including: 5x cable gland (cable entry)
•    Connected load: 2x 1,000 W
•    Output: 2x potential-free relays 5A
•    Relay contacts: NO/NC = changeover
•    Connection voltage: 230 Volt
•    Internal consumption: 1.5 W (at rest)
•    Temperature control range: 0...+99 °C
•    Temperature differential: 1...30 °C
•    Switching hysteresis: 1...20 ºC
•    Operation: via 4 push buttons
•    Sensor inputs: 2x Pt1000
•    LCD display: 60 x 15 mm
•    Indicator lights: 4x LED
•    Security class: IP20
•    Manual: German
•    Weight: 600 g
•    Test mark: CE

Basic knowledge of electrical and control engineering is required for connection and commissioning.