The DUWACO roof-top heat pump is a system which, unlike air-water heat pumps, works on the basis of the air-air principle. Instead of fan coil units, DUWACO installs two air bags (an air inlet and an air outlet) in the walls. For larger requirements a multiple of two is installed.

The number of air bags installed and the required capacity of the heat pump will depend on various factors, including the insulation present. This system is very suitable for shops, for example, where it is not possible to install fan coil units because the walls are fitted with racks.

Besides heating, the roof-top heat pump can also provide cooling. If the temperature of the outdoor air is colder than the temperature set, use is made of ‘this free source of cooling’. Free cooling entails the supply of fresh air without the compressor being switched on, which therefore does not consume any energy. If, for example, the outdoor temperature is 18 degrees, the indoor temperature is 22 degrees and the temperature set is 20 degrees, the system can cool without having to consume energy in the process.

Roof-top heat pumps can be expanded with an optional CO₂-driven system. The more people there are in a specific room, the higher the temperature and the CO₂ level, and the roof-top heat pump adjusts the CO₂ exhaust speed accordingly. This adjustment is automatic and continuously variable. The heat in the CO₂ is, at the same time, reused to heat the fresh air supplied. Roof-top units are available in the following models:

10 – 12 – 14 – 17 – 20 – 22 – 25 – 28 – 30 – 32 – 35 – 42 – 48 – 52 – 63 – 72 – 90 – 105 – 120 – 130 – 150 – 170 – 190 kW.

The advantages of the roof-top system are as follows:

• short heating time;
• highly efficient at heating;
• it cools and heats;
• simple to install;
• flexible: a large variation in pipe lengths is possible; 
• requires little maintenance;
• performs powerfully;
• very efficient, giving a high output;
• robust: the heavy-duty housing protects it from weather conditions varying from -10 °C to +45 °C;
• safe to use;
• produces little noise;
• meets international quality standards, such as CE, ISO14001 and ISO9001:2000;
• an optional application for the supply of extra fresh air (50%+) and an optional economiser are available for most models, for extra cost reductions.