Krack – a brand of U.S-based OEM Hussmann – has launched its microDS Monoblock, a propane (R290)-based, self-contained refrigeration unit for walk-in cold rooms and freezers.

It was featured at the FMI (Food Industry Association) Energy and Store Development (ESD) Conference, which took place in Orlando, Florida, September 19–21.

Details of Krack’s new microDS Monoblock system were shared by Ronald Grabowski, Senior Product Leader at Hussmann, during an interview with at the ESD conference.

The top-mounted, water-cooled unit combines the evaporator with the condensing unit into a single packaged system, explained Grabowski. It attaches to a water-loop system that removes excess heat from the unit and transports it to a roof-top condenser where the heat dissipates.

The microDS Monoblock is part of Hussmann’s microDS product portfolio, which was launched in 2018 and includes a wide range of propane-based, self-contained display cases. According to Grabowski, the Monoblock is well-suited to sites that already use Hussmann’s microDS cases as it connects to the same water-loop system. 

Each self-contained unit is pre-charged with 150g (5.3oz) of propane so requires no field refrigerant piping. According to the manufacturer, not only does this approach reduce installation time, but it also reduces cost due to its requiring 90–95% less refrigerant charge compared to systems using HFCs.

By using propane, the Monoblock is also compliant with California Air Resources Board (CARB) regulations and the American Innovation and Manufacturing (AIM) Act.

“If you’re energy conscious and want to go with natural refrigerants, you could choose this in place of a condensing unit with HFCs,” said Grabowski. “Some customers don’t want CO2 [R744] based on challenges with energy and where they’re located, so propane is good for them.”

“If you’re energy conscious and want to go with natural refrigerants, you could choose this in place of a condensing unit with HFCs.”

Ronald Grabowski, Hussmann

System specs

The microDS Monoblock is available in both medium-temperature (MT) and low-temperature (LT) models. For MT, the unit provides temperatures from -2.2°C (28°F) to 10°C (50°F), with a cooling capacity of 2.6kW (0.7TR) to 6.1kW (1.7TR). The LT model offers box temperatures from -26.1°C (-15°F) to -15°C (5°F) and a cooling capacity from 1.2kW (0.3TR) to 3.5kW (0.9TR).

The unit is designed with “the latest in variable-speed evaporator motor and compressor technology,” and includes energy-efficient EC motors and hot-gas defrost with heated pan, according to Krack.

Where additional cooling capacity is needed, for example at a microfulfillment center or a larger supermarket, Grabowski explained that multiple units can be added to a room.

During the interview, Grabowski noted that the microDS Monoblock is generally better suited to larger retail stores due to the need for a waterloop system. In his experience, smaller stores tend to use air-cooled equipment, which require less investment, he explained. Grabowski added that Krack would be launching an air-cooled version of the microDS Monoblock early next year. This will be the microSC Monoblock, which will be part of Hussmann’s microSC product portfolio

The Krack brand, which was acquired by Hussmann in 1976, covers unit coolers and condensers.

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