the System of heating isolated from atmosphere, possesses certain capacity. Internal hydraulic pressure in the closed system filled with water at rise in temperature and aspiration of water to expansion raises and can surpass strength of its separate elements. Therefore into system of water heating it is entered dempfer - a broad tank (fig. 53).
the Basic purpose of a broad tank - reception of a gain of volume of water in the system, formed at its heating, for maintenance of certain hydrostatic pressure. Besides, the tank is intended for completion of a decrease of volume of water in system at insignificant leak and at fall of its temperature. Through an open tank surplus of water in a drain leaves at system overflow.
the Second important appointment of a broad tank is a gathering of air allocated from water at its heating in teplogeneratore. Air gets to system with tap water in which at its room temperature it is dissolved about 40 mg/l. At heating to maksimalnoraschetnoj heating temperatures (+95 ° rastvorjaemost air decreases approximately to 3 mg/l. The allocated air vials emerge in a water stream on the main strut in a broad tank from which leave in atmosphere.
53. An open broad tank with branch pipes for joining of pipes
1 - a broad branch pipe; 2 - perelivnoj a branch pipe; 3 - a branch pipe of a control pipe; 4 - a circulating branch pipe; 5 - spusknoj a branch pipe with a stopper
Broad tanks have a number of lacks : they are bulky, in this connection their placing in premises is at a loss and useless losses of heat through their walls increase at an arrangement of tanks out of a premise. Besides, at opened (not tight) tanks water absorbs air that strengthens internal corrosion of pipes and devices from atmosphere.
the Open broad tank (fig. 53) place over the top point of system of heating, as a rule, in a garret of a building or on a staircase and cover with thermal isolation.
Tanks make the standard sizes under typical drawings, cylindrical or rectangular, from a sheet steel and from above supply with the hatch for survey and colouring. In the tank case there are some branch pipes:
- the branch pipe 1 is intended for joining of a broad pipe on which water arrives in a tank;
- a branch pipe 4 - (at a bottom) for a circulating pipe through which water for heating system is taken away;
- a branch pipe 3 - for a control (alarm) pipe;
- a branch pipe 2 - for connection of a tank with perelivnoj a pipe informed with atmosphere.
the Control pipe 3 deduce to a bowl and supply zapornym with the crane. Vytekanie waters at crane opening should testify to water presence in a tank, and consequently, and in system (the water level should not be below shown on fig. 53 shtrihpunktirnoj a line).
Useful volume of a broad tank , limited in the height h p (fig. 53), should correspond to increase in volume of the water filling system of heating at its heating to average settlement temperature.