In 2004 it was decided to improve the distribution of heat through the apartments to solve some complaints with the system and to save energy. To simplify the commissioning and increase the precision Platen chose to use the Danfoss AB-QM to control the flow to the apartments.
The AB-QM is a valve with a built in flow limiter which has an extremely easy and fast setting. So, instead of having to go around with measuring equipment to try to balance the system manually, the installer could just set the AB-QM to the right flow during the system upgrade and finish the complete installation in one go.
After the installation of the AB-QMs the occupants of the apartments have no complaints about the heating anymore. Where previously some apartments would be difficult to heat because of bad balance in the system, now everybody can heat his apartment to the required temperature.
The building society is also happy. According to Swedish law the heating bill should be included in the rent. This means that the building society is very interested in saving energy. Any water pumped around unnecessarily will add to the bill. Not only because of pumping cost but also because it will decrease the differential temperature across the installation which in turn reduces the efficiency of the district heating system or the boilers.
To see if the investment in AB-QMs paid off they calculated the energy use of the apartments and corrected them for the degree days. The results were impressive. In 2004 the energy use was 262.8 kWh/m2 , in 2006 the energy use was only 232.1 kWh/m2 , a reduction of well over 10%! Since every KwH costs 60 öre this represents a saving of 141.300 SEK (~€ 14328,-) every year. The investment in AB-QM will earn itself back very fast!
To finish the renovation, the Platen building society will replace the old wax radiator thermostats with new gas-filled ones in 2007. They expect they can save even more money after that change, as well as increase the comfort of the Ekön residents because of the high precision of gas-filled thermostats.