How do you really ensure that the calculation method used to calculate heat outpur on a radiator is the right one? At Hudevad, our technicians have, in collaboration with the Danish Technological Institute, conducted a study on which methods provide the least possible deviation between the actual performance to the calculated performance.

The study is based on the European heating standard EN 442, which prescribes how to calculate radiators heating outputs. The European norm is based on a temperature set (75/65/20), which seen with Danish eyes, is too high. In Denmark, where district heating is much more prevalent than in many other European countries, typically a much lower temperature set is used and therefore a much larger degree of cooling. To compensate for this difference, there are two conversion methods according to which the actual heat outputs are calculated: the logarithmic and the arithmetic method

The Danish heating standard DS469, which is based on the European standard, has recently received a so-called "informative supplement". The supplement recommends that the conversion be performed by the logarithmic method unless otherwise recommended by the manufacturer. This is not entirely clear and our work with the Danish Technological Institute shows that where the logarithmic method is better for some products, the arithmetic method is better for others.

We have emphasized in our calculations that the deviation between calculated and actual performance should be minimal. This means that all low convectors are converted according to the logarithmic method and the majority of the panel radiators after the arithmetic.

The study and the underlying calculations made by the Danish Technological Institute and Hudevad will be published in full length in one of the future numbers of the HVAC Magazine.

Do you have questions about the calculation of heating output? Then don't hesitate to contact us at or by phone +45 76 88 22 00.