Through the new split-bottom with slit-shaped gutters, the quick drainage of rain and defrost water is enabled. An electric heating system for the complete bottom area as antifreeze prevention is no longer necessary, which reduces the annual electrical energy consumption of the system. The slit shaped gutters avoid the risk of a blocked drain connection, as there is no requirement for the drain connection. During heat pump operation, the only recommendation is to install a heating cable along the slit shaped gutters to prevent frost. This heating cable can also be retrofit later, when it is clearly required. The split-bottom is installed in the housing types KV and KH as standard without additional costs.