New refrigeration technology: what has changed, what has remained the same

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New refrigeration technology with more power in the low temperature range

Our new CO2 refrigeration technology achieves a test chamber temperature of up to −50°C in our climate chambers and temperature chambers. It is more powerful in the low temperature range than the previous −40°C refrigeration technology. At the critical point of −40°C for many test standards, the new refrigerating units still provide considerable cooling capacity and heat compensation. Traditional, single-stage refrigeration technology can hardly cool test specimens below −30°C.

In all Weiss Technik test chambers, the previous −40°C refrigeration technology is being replaced by new CO2-based refrigeration technology without changing the design, connections, and dimensions of the units. The environmental parameters also remain the same. Infrastructure such as cooling water, connectors, and accessories can continue to be used. Only a few technical parameters have changed.

Advantages of the new CO2 refrigeration technology


The performance parameters are determined with an empty test space according to IEC 60068-3-5. The cooling rate is specified in the range of 10–90% of the temperature range. Thanks to the CO2 low temperature of −50°C, the test chamber will maintain the specified cooling rate down to at least −27°C (temperature range 180°C to −50°C corresponds to 230 K. 10% is 23 K. −50°C + 23 K = −27°C).


Natural refrigerants such as CO2 are not F-gases. The EU directives therefore do not apply to CO2 refrigeration systems. Many recording obligations, quota regulations, and repair regulations no longer apply. Leakage tests are required only according to EN 378 (ISO 5149-4) and no longer according to the GWP value. Carbon dioxide as a refrigerant is given a GWP of 1.


Many relevant test standards such as IEC 60068-2 contain preferred temperatures (e.g. −40°C). At this temperature point, previous single-stage units with R449A no longer have any cooling capacity. Users had to resort to cascade refrigeration systems with two refrigeration circuits. These are complex and therefore more expensive. Our cost-effective CO2 refrigeration still has sufficient cooling capacity/heat compensation even in the low temperature range.


Climatic chambers and temperature chambers are a source of noise in the laboratory. Compressors and switching valves generate a disturbing noise. Components for CO2 refrigeration technology are considerably smaller and quieter with the same output. The housing fan is now often the loudest component. Because it typically only runs sporadically, CO2 test chambers are barely audible. The noise level is regularly below 50 decibels (quieter than in the office).

Notes on CO2 refrigeration

units with CO2 refrigeration technology

New: Fuses with 300mA required due to frequency converters

The cooling water temperature remains the same: 12-28°C.

Ambient temperatures of up to 35°C are no problem.

The dimensions, size and footprint of all appliances remain the same.

The new Simpac 2.0 controller has a ring buffer, Linux, and NTP.

An electronic cooling water regulator allows a lower water pressure.

The new CO2 refrigeration technology can cool down to -50°C.

Power consumption and power consumption are lower than before.

Lower sound pressure level: CO2 refrigeration has smaller, quieter components.

IEC 60068-2-14 Nb: Sufficient heat compensation in the holding phase at -40°C. No cascade system necessary.

System pressure up to 120 bar, but significantly smaller cross-sections and volumes. No problem with the Pressure Equipment Directive.

CO2 has GWP1 and is not flammable.