A new infrared (IR) radiator with a gilded parabolic reflector is used to warm the culture broth.
The heat radiation (150W) is concentrated on the bottom of the vessel where it is absorbed by the medium in a similar way to the sun heating water.
There is no overheating at any volume of the culture (common with heaters placed directly in the medium). Thanks to the low heat capacity of the IR source, overshooting of the temperature is reduced and the temperature can be controlled more precisely.
The temperature sensor is placed directly in the pH sensor and is used at the same time for an automatic correction of pH and pO2 electrodes.
Infra-red heat rays provide soft heating and optimal temperature maintenance. Natural thermal convection takes place even without any mixing of the culture. This novel heating system is also very convenient; because cables, tubing, connectors, the necessity of heating blankets or jacketed vessels and circulating water supplies are completely eliminated.
When the temperature is attained, volume of warmed water in the jacket and bath must be cooled down to prevent temperature overshooting. It is obvious that the temperature control is much more difficult than with radiation heating.
For example: The variation of the temperature set to 30°C gives deviations of only ±0.1°C in a one liter vessel!