An evaluation of a novel test method for anti-scale devices.- A case study from Sauherad, Norway
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- NIVA-rapport 
The Danish Technological Institute (DTI) and The Norwegian Institute for Water Research (NIVA) have developed a test method based on research from Cranfield University about magnetic fields applied on re-circulation systems and DVGW W512 for evaluating anti-scale devices for hot water treatment. Test results and experiences from two tests conducted in a Norwegian municipality with scaling problems in hot water installations are presented. During the first test an old magnetic anti-scale device was examined without re-circulation. Scales were formed on the heater elements both for the treated and non-treated water (control), although the anti-scale device reduced the scale formation in one case. 3.7% and 5.0% of the influent calcium were converted into scales in the line with and without an anti-scale device, respectively. During the second test a new anti-scale device was examined with re-circulation. Here, the scale formation from the treated water in fact increased. During re-circulation 11.9% and 7.0% of the influent calcium were converted into scales in the line with and without an anti-scale device, respectively. The anti-scale devices were not able to prevent scale formation on the heater elements in the test rig. The results raise some questions about the efficiency of the tested anti-scale devices and the test methodology itself. To gain more experiences with this system the tests should be repeated with various anti-scale devices, and the system itself should be tested with pressurized water.