Distributing heating collectors are purchased readymade or assembled from factory parts (see Figure 32). It is possible to make the collectors by yourself from usual steel pipes. The internal diameter of distributing collectors is chosen according to the supply of warmth carrier through the heating contour in such a way that the velocity of the water in the collector should not be more than 0,7 metres per second. The calculation is not difficult to make, knowing that the supply of warmth carrier should be equal to the building heat loss, Q = P, where Q is the supply of warmth carrier in the heating contour, in litres per minute; and P is the heat loss of the building which is equal to the output of the heating radiators and «warm floors» and equal to the boiler output in kilowatts. We determine the diameters of the collectors by the amount of water in the supply and its velocity. For this, we need only to convert litres into cubic millimetres and calculate the cross-sectional area of the collectors.
To remove slime and to drain the heating system, outlets are inserted and ball valves are installed in the home made collectors. Also to remove slime, there are special devices which are installed on the return pipeline of the boiler piping. We have already partly dealt with this problem, describing the air separator with a stopper to remove slime, but separators are quite expensive and therefore they are installed on the heating systems with boilers with output more than 60-100 kilowatts. In low-power boilers, using equipment which cost more than the boiler itself is not wise; therefore so-called deslimers are installed (see Figure 33). In addition, the air separator is installed on the supply line, right after the boiler, but the slime is better removed from the return pipeline. The principle of how deslimers work is based on the combined action of several physical phenomena. The internal element consists of the aggregation of mesh surfaces which are arranged like a fan. The slime which is present in the water, encountering these surfaces, separates and falls into the lower part of the device’s housing, in which it accumulates. Moreover the large internal volume of the deslimer decreases the velocity of the flow of the liquid and the slime, due to gravity, settles. Draining the accumulated slime is done not only when the heating system is switched off, but also while the system is running by opening the draining valve with a special wrench. In very simple heating systems, deslimers are not installed. In this case, they are replaced by dirt filters and on each side of them manometers are installed. According to the indications on the manometers before and after the dirt filter, we can judge whether the filter is filled. As it fills, it must be cleaned manually. This method is, although the cheapest, not the most reliable because it requires periodic monitoring of the heating system and cleaning the filters. Deslimers also require observation but the principle of their work is slightly different: in filters, slime fills the mesh filter and clogs it; but in deslimers, the slime hits the mesh and falls down. The grid, however, remains clean.