Collection: Differential Thermostats

Differential Temperature Controllers

This type of temperature control is suited to applications where the difference between the two measured values should trigger a control output or alarm. Unlike standard digital thermostats or PID controllers, Differential Controllers are equipped with two sensors to measure two reference points. Their control applications can be thought of as energy transfer - where one source (collector) is moved to another point to maintain or benefit the overall process.

All of our differential controllers come with 2 x NTC sensors supplied. In most environments the sensor wiring can be easily extended using 0.5mm CSA cable. Sensors can be mounted directly to pipework where good conduction of heat is possible. The provided sensors are also suitable for general measurement in free air.

Options are available for different controller supply voltages. Novus controllers will operate on 12~24V or 100-240V depending on which model is selected. There are also options for RS485 communications which allow serial data exchange with the unit.

Where Are Differential Temperature Controllers Used?

The objective in a control scenario is normally to maintain a minimum difference between the two measurement points. When the differential is exceeded a control action is initiated via the built in relays.

In a solar heating system: the output could be connected to a water pump, this has the effect of raising the temperature at the reservoir and lowering the collector reading. Hot water from the collector is pumped to the reservoir and cold water is recirculated back for heating. The outcome is to progressively increase the reservoir temperature.

Control applications include: solar water heating, air destratification, grain drying, climate control in buildings and animal enclosures. Typically the outputs are wired to pumps, fans or valves. Either directly or via components such as contactors and relays.

Differential thermostats can also be used for general monitoring of two temperature sensors i.e. as a 2 channel thermometer. Models equipped with RS485 can be linked to Data Loggers, BMS and SCADA systems to provide trending and historical logs.

Can You Supply Enclosures, Extension Cable & Spare Sensors?

We are frequently asked about the best methods to mount Differential Controllers. One of the simplest is to use a standard blank enclosure with suitable IP rating. We stock products from Wiska such as the 818A or Indubox 1308AR/W.

We also sell extension cable for the sensors (by the metre) and replacement sensors.