Skip to main content

Guide to Thermostats vs. Digital Temperature Controllers

digital temperature controller

Understanding the Pros and Cons of Thermostatic Controls

All of EIC’s ThermoTEC™ thermoelectric air conditioners are equipped with thermostatic control. Whether the unit is only equipped for cooling or includes an optional heating function, the thermostats allow the air conditioner to maintain the proper temperature levels within the enclosure. We also offer an optional digital temperature controller that allows for tight precision control of both the heating and cooling cycles. Both configurations have their benefits as well as their limitations.

Standard Thermostats

Our standard integral thermostats are used on all units. The cooling thermostats are fully adjustable from approx. 100°F (38°C) down to 0°F (-18°C). This thermostat will engage as the temperature within the air-conditioned space rises above the set point. These types of bimetallic thermostats have a hysteresis of approx. +/-5°F (2.6°C). This allows the air conditioner to shut off and “rest” as the temperature rises back to the set point or slightly above.

ThermoTEC™ coolers that are also equipped with heat use two thermostats: one of the adjustable thermostats mentioned above to control the cooling cycle and one fixed point thermostat to control the heating portion. This fixed point heating thermostat is designed to engage the heat at approx. 45°F (7.2°C) and end the heating cycle at approx. 55°F (12.8°C). These set points were chosen based on the acceptable operating temperatures for the large majority of equipment.

If a heating thermostat is being used, the cooling thermostat should not be set any lower than 70°F (21.1°C) to prevent both the cooling and heating functions from trying to run simultaneously. The only ThermoTEC™ unit that does not use this arrangement is the 140 Series, which uses two fully adjustable thermostats. We still recommend the same amount of dead band between the two set points.

Benefits of the Standard Thermostat include:

  • Fully integrated design
  • Fully adjustable cooling cycle
  • Reliable mechanical operation
  • Tested and proven in over 25,000 units

Digital Temperature Controllers

Some of our customers desire a greater level of control than our standard thermostats offer. In this case, EIC can offer a digital temperature controller (#DTC-R). This sophisticated proportional-integral-derivative (PID) controller allows for precise temperature control using both the heating and cooling portions of the air conditioner to reach one set point. If the air conditioner is sized appropriately, the digital temperature controller can maintain temperatures as tight as +/- 1°F of the desired set point. This controller is also equipped with an Autotune PID feature. While in the tuning mode it can “learn” the cooling process over time and provide temperature control designed for your specific process profile. These controllers can be mounted through the wall of the enclosure, allowing for full access and control from the ambient side of the enclosure. They can also be mounted remotely in a nearby control panel if desired.

The remote-mount thermocouple also can be placed anywhere within the enclosure. This can be especially helpful if there is a particular hot spot within the enclosure that is of concern. The digital temperature controller is also available with RS-232 output (#DTC-R232) for controlling the cooling system remotely through an RS-232 connection.

Benefits of the Digital Temperature Controller include:

  • PID and Autotune features
  • Optional RS-232 connection
  • Precise temperature control
  • Accessible from the ambient side of the enclosure

Both temperature control options can help to keep your electronic equipment at optimum operating temperatures. The simple adjustable thermostat and the more sophisticated digital temperature controller are readily available and designed to withstand the harshest of environments. Contact one of EIC’s sales engineers today for help in choosing which controller will best meet your needs.