Examples of thermal characteristics of selected radiators.

The table shows these types of characteristics for Rettig-Ratec and Purmo radiators. Choosing radiators, outside the pre-determined heat demand, other requirements should also be taken into account, and especially the supply temperature of the radiator. This can be equal to the calculated supply temperature, but it is also necessary to take into account the cooling of the heating medium (especially in upper-section heating or single-pipe heating). In these heatings, changes in the temperature of the heating water flowing to subsequent radiators should be taken into account. The selection of radiators is made as for two-pipe heating, by introducing coefficients for the correction of heat output:is the corrected heat output of the radiator for two-pipe heating conditions (In), Qg is the required heat output of the selected radiator (In), and Φ is a correction factor depending on the operating conditions of the radiator. These coefficients depend on the so-called. relative cooling of the refrigerant (Xn) in single-pipe heating (see table).

Correction factors Φ for the selection of radiators in single-pipe heating systems.

In a number of studies and catalogs of manufacturers, you can find other indicators for assessing radiators. Some of them are listed in the table.

Selected indicators of the assessment of heaters.

As you can see, these indicators depend on the ratio of the heaters' heat power to their weight, surface, water and heat capacity, building area and prices. They make it possible to select heaters with the most advantageous solutions, not only due to their hydraulic and thermal properties, but also because of the price and the use of indoor space.

One should also remember about the problems of using heaters made of aluminum and connected with pipes made of other metals (mainly of steel and copper), as highlighted earlier. Equally important are issues related to ensuring the correct operation of radiators in conditions of changing thermal needs of rooms and buildings, which entails the need to limit the thermal power of radiators. This can be achieved both by means of central operational control (made in heat sources), as well as individual adjustment (implemented with thermostatic valves). The most commonly used is mixed regulation, which is a combination of central qualitative regulation with local quantitative regulation.