Abstract: A laboratory thermostat features a heating and/or cooling device for temperature control of a liquid bath medium located in a bath tank. The laboratory thermostat has an early-warning system with a control device for a low liquid level in the bath tank and an evaluation device that can realize at least an acoustic and/or visual warning message for maintaining the temperature control process. Due to the integrated early-warning system, when the liquid level decreases, the user of the laboratory thermostat is made aware in due time before undesired shutdown by a low-liquid-level protection device, so that lost temperature control fluid can be immediately refilled before the safety shutdown is triggered by the low-liquid-level protection device.

Abstract: A laboratory thermostat (1) has a bath container (2) for liquid (3) to be tempered as well as a heating device and a refrigerating unit (4). The refrigerating cycle of the refrigerating unit (4) has a compressor (5), a condenser (6), an evaporator (8), as well as an expansion valve (7) controlled by a temperature sensor (10) arranged at the evaporator outlet. In addition, a regulation device (11) is also provided which is connected to a temperature actual value sensor (12) for recording the bath temperature. So that the temperature of the bath liquid can be adjusted to various values and regulated, the temperature sensor (10) of the expansion valve (7) is in thermal contact with a tempering apparatus controlled by the regulating device (11). The extent of the tempering is determined by the regulation device (11) according to the adjusted bath temperature output and the bath temperature measured by the temperature actual value sensor.