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Process thermostat for energy-saving professional temperature control in the working range of -90 up to 200 °C

LAUDA process thermostats of the Kryoheater Selecta (KHS) series ensure high-performance temperature control at high energy efficiency and reliability. The compact device construction provides a long service life and maintenance friendliness.

Corresponding to the lowest working temperature, two-stage compressors (up to -60 °C) and/or cascade cooling systems (up to -90 °C) are used. The condenser is cooled by means of cooling water. The cooling capacity is controlled continuously and precisely by injection control. A step switch ensures energy-saving and low-wear partial load operation using an automatic compressor system. By means of the electric heating, Kryoheater Selecta can cover an operating temperature of up to 200 °C.

Application examples

  • Test stands
  • Reactors
  • Distillation plants
  • Freeze-drying
  • Temperature stress test for environmental simulation

Download a PDF of our Kryoheater brochure:

LAUDA Kryoheater Selecta Brochure (1.9 MB)

Working Temp Min.

Working temperature min.

-90 °C

Working Temp Max.

Working temperature max.

200 °C

Temp Stability

Temperature stability

0.5 ±K

PLC control with 7 “touch panel for intuitive operation and extensive data exchange with process control systems

Safe and reliable useage in production environments thanks to protection class IP 54 and robust construction of the device thanks to steel frame


Powerful pump (flow rate 85 L/min max. pressure 5.5 bar max.) – high volume flow even in case of pressure loss


Magnetic coupling – no sealing problems at the pump shaft as it is hydraulically sealed


Integrated frequency conversion – highly precise user-specific speed control (40 to 100 percent)


Pressure limitation – protection of the consumer against excess pressure


Nitrogen overlay of the expansion vessel – no condensation of the air humidity


Pressure-resistant expansion vessel made of stainless steel – no odours; no evaporation and no oxidation of the heat transfer liquid; enables larger operating temperature range of the heat transfer liquids


Automatic on/off of the second refrigeration step for KHS 2190 W (cascade cooling up to -90 °C) – up to 50 percent energy conservation in applications over -20 °C


Protection class IP 54 – safe, reliable and long-term use in production environments


Robust construction using steel frames – protection of the control against all environmental influences, such as dust, dirt, liquids and touch


Industrial control cabinet – simple maintenance and service by ideal accessibility to all components


PLC control (programmable logic controller) – extensive data exchange with process control systems


7″ touch panel – intuitive operation


Detailed display of parameters – quick analysis of process data


Visualisation of alarm and error messages – identification of disturbance variables


Use of a refrigerant with low global warming potential (GWP* < 2,500) – fulfills the European F Gas Directive No. 517/2014


Low amount of refrigerant

The Kryoheater Selecta series consists of the two systems KHS 3560 W and KHS 2190 W, which are used in chemical and pharmaceutical production as well as for the simulation of environmental conditions in test stands of the automobile and aerospace industries.

Advantages ensured by nitrogen overlay

A nitrogen overlay permits the insulation of the heat transfer liquid from atmospheric oxygen in pressureless operation. This prevents an oxidation at high temperatures. Thus the life of the heat transfer liquid is extended drastically on the one hand and in addition the maximum operating temperature permitted is increased. In addition, the overlay prevents the condensation of air humidity at low temperatures. The Kryoheater Selecta process thermostats have been designed for pressurised operation. By a pressurized operation with nitrogen the advantages mentioned above are reached, and in addition the boiling points of the heat transfer liquids and thus the maximum permissible operating temperatures are increased.

Interface/data protocol

  • Lemo sockets for external temperature control
  • USB interface to read out data and for information transmission for diagnosis or configuration
  • A freely selectable analog or digital interface

Simple and intuitively designed user interface:

  • Visualisation of heating and cooling circle, warning messages and failures
  • Clear overview of the parameters – directly recognizable on the piping schematic

PLC (programmable logic controller) fitted in an industrial switch cabinet

  • Comfortable and extensive interlinking with other IT systems
  • High process transparency ensured by large information density in the control system
  • Long-time compatible, vibration-resistant, maintenance-free and scalable
  • Extremely high reliability
  • Remote maintenance and remote diagnosis (update of parameter sets or software online possible)
Select up to 3 products to compare:
Compare Products
Kryoheater Selecta Process thermostats
Technical features KHS 3560 W KHS 2190 W
Select to compare:
Working temperature min. °C -60 -90
Working temperature max. °C 200 200
Bath volume min. L 15.0 15.0
Cooling output at 20 °C kW 35.00 21.00
Temperature stability ±K 0.50 0.50
Heater power max. kW 18.0 18.0
Pump pressure max. bar 5.5 5.5
Pump flow max. L/min 85 85
Cat. No. 400 V; 3/PE; 50 Hz LWP 556 LWP 557
Cat. No. 440-480 V; 3/PE; 60 Hz LWP 656 LWP 657
Cat. No. 400 V; 3/PE; 50 Hz & 440–480 V; 3/PE; 60 Hz LWP 756 LWP 757

Heat transfer liquids

Unit Kryo 65 Kryo 70 Kryo 90
Cat. No. 10 L LZB 218 LZB 227 LZB 228
Cat. No. 20 L LZB 318 LZB 327 LZB 328

Cooling water tube EPDM

Cat. No. Description di (mm) da (mm) Pressure range Temp. range (°C)
RKJ 033 Fiber-reinforced 25 34 max. 10 bar -40…100
Stainless steel tube clip
EZS 016 External ∅; 1″ 25–40

Metal hoses with cold insulation

Cat. No. Description di (mm) da (mm) Length (cm) Temp. range (°C)
LZM 094 M38X 100S 25 78 100 -100…350
LZM 095 M38X 200S 25 78 200 -100…350
LZM 096 M38X 300S 25 78 300 -100…350

Quick coupling

Cat. No. Description Material
EOF 539 With 1″ internal thread Brass
EOF 540 With hose nozzle 1″, attachable with counter nut Brass


Cat. No. Description Material
EDF 222 Flat graphite gasket DN25-PN40 DIN 2690
HKA 198 Flange adapter M38 x 1,5 A to DIN 2633/DN25


Cat. No. Description
LWZ 936 Remote maintenance by modem
EZ 214 Machine foot in steel with height adjustment
LWZ 942* Additional expansion vessel, filling volume 50 L

*Installation of an optional expansion vessel causes an enlargement of the housing height from 1,650 to 2,350 mm.

Cooling process of a 250 L reactor between 20 and -50 °C

  • High efficiency for every temperature setpoint value by using precisely harmonised refrigerants and frequency-controlled compressors. In case of KHS 2190 W, the two frequency-controlled compressors are automatically run in single or two stage operation depending on load and temperature.
  • Transport of the heat transfer liquid with the required pressure by means of the 2.2 kW magnetically coupled and frequency controlled pump in the external consumer, such as a reactor.
  • Limitation of the outlet temperature; programmable temperature ramps as well as Delta T limitations to take minimum and maximum temperature loads of reactors into consideration.
  • Link to the process control system by various interface options enabled by the standard Siemens PLC control