Heating as well as cooling causes gradual depositing in water and heating systems of mineral and organic substances always contained in input water. In systems operating over long periods of time, there is always the formation of solid depositions (incrusts formed mainly from calcium and magnesium carbonates, sulphates and iron compounds) and deposits on heat transfer surfaces in spite of the dosage of corrosion inhibitors and substances against the formation of deposits. Such reduce the efficiency of the facility resulting in insufficient heat transfer. The discharged substances can additionally cause the obstruction of the systems (heating system distribution lines, fittings, exchangers, etc.). 

In places with reduced circulation (e.g. radiators, hot water tanks) there are additionally deposits in the form of dregs which comprise organic sediments and released particles of solid incrusts. These are formed not only on metal pipelines and fittings but also on the surfaces of plastic pipelines and fittings. These particles are then released e.g. during the interruption of circulation, discharging and filling operations during repairs of the systems. Partial releases can occur through pressure flushes in the system during normal operation, particularly in plastic distribution systems where incrusts and deposits do not adhere firmly.

These deposits cause trouble in following areas:
- they increase energy losses due to heat transfer impairment, the sediments act as a good heat insulator, e.g. approx. 1 mm incrustation layer reduces heat transfer efficiency on heat transfer surfaces of exchangers and radiators by approx. 5%.
-they reduce the clear area of pipelines, exchangers and radiators, they limit and in extreme cases make the circulation of heating or hot water impossible, they increase hydraulic losses due to which the consumption of circulation and closed-circuit pumps rises.
- they negatively influence the functioning of fittings, control valves (particularly low-lift heat regulator valves), measuring and control elements, clogging up the heat meters.
The problem of deposits affecting the individual system elements is extensive and the precise analysis and effects vary based on the types of systems according to complexity, operating method and regulation. In addition there is synergic influencing of partial effects on energy efficiency, flow, influencing the control elements, etc.

In general the following effects occur as a result of system deposits:

A) increase of heat losses in distribution systems,

B) increase of consumption of circulation and closed-circuit pumps due to increased hydraulic losses,

C) insufficient heating of structures due to deterioration in heat transfer in radiators and decrease in heating water flow,

D) failure to reach set hot water temperatures on outlets at end customers,

E) increase in expenses for repairs and maintenance of fittings, control and measuring elements,

F) reduction in the service life of the single elements in systems due to corrosion and mechanical damage through deposits.
The resulting repairs definitely make the operation more expensive, systems have to be replaced in a number of cases. Regular maintenance can prevent these financial and energy losses. One of the methods is chemical cleaning which significantly helps to extend the service life of the facilities and eliminate adverse effects of deposits, dregs and incrusts. The excellent condition of the system is of fundamental significance for efficiency and reliability and is directly related to minimizing operating costs.

The assets of chemical cleaning can be summarized as follows:

1) removing water scale sediments, deposits, biological segments, pitting corrosion,

2) increasing the heat output,

3) preventing the clogging of heat regulating valves and other system elements due to corrosion and mechanical damage through the sediments

4) preventing corrosion,

5) increasing the system efficiency,

6) reducing operating costs, 

7) extending service life of systems, thus distinctly postponing investments in new facilities.