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System of water heating
With natural circulation of the heat-carrier

the Basic scheme of system of water heating with natural circulation of the heat-carrier is shown on fig. 1. Water from a copper to devices of the heat exchanger and back moves under the influence of the hydrostatic pressure arising thanks to various density cooled and nagretoj of a liquid (heat-carrier).

Systems of water heating with natural circulation (the top distributing)

a Fig. 1а. Systems of water heating with natural circulation (the top distributing)
1 - a copper; 2 - the main strut; 3 - a planting line; 4 - hot struts;
5 - return struts; 6 - a return line; 7 - a broad tank; 8 - an alarm line

What force forces water to circulate in system , i.e. To move on pipes from a copper to heating devices and back in a copper? This force arises at water heating in a copper and its cooling in heating devices. Water, nagretaja in a copper 1 as easier, rises on the main submitting strut 2 upwards.
From a strut it arrives in planting main pipelines 3, and from them through submitting struts 4 - in heating devices. Here water cools down and consequently becomes heavier. For example, the water density at 40 ° With makes 992,24 kg/m 3 , at 70 ° With - 977,8 kg/m 3 , at 95 ° With - 961,9 kg/m 3 . The Chilled water through return struts 5 and a return line 6 falls downwards and in the weight supersedes nagretuju water from a copper upwards - in the main submitting strut.

Systems of water heating with natural circulation (the bottom distributing)

a Fig. 1б. Systems of water heating with natural circulation (the bottom distributing)
1 - a copper; 2 - an air-line; 3 - a planting line; 4 - hot struts;
5 - return struts; 6 - a return line; 7 - a broad tank; 8 - an alarm line

the Described process continuously repeats and as a result there is a constant circulation of water in system. Force of circulation, or as it is accepted to speak, circulating pressure, depends on a difference of scales of a column hot and a column of the cooled (return) water, hence, it depends on a difference of temperatures of hot and return water.

Besides, circulating pressure is caused still by height of an arrangement of the heating device over a copper : the the device is above located, the it is more for it circulating pressure.

It is possible to prove It as follows. The greatest temperature of hot water is usually equal in systems of water heating 95 ° With, and cooled - 70 ° S.Esli to neglect water cooling in pipes it is possible to consider that in the heating device water arrives with temperature 95 ° With, and leaves it with temperature 70 ° d we will define at first for top, and then for the bottom heating device circulating pressure under which influence there is through them a water movement.

We Will spend on fig. 1а dotted horizontal lines through the centres of heating devices and a copper. We will admit that these lines are border between water with temperature 95 ° With and water with temperature 70 ° S.Ochevidno that on site BVGDL the water temperature will be identical and equal 95 ° With, hence, here there can not be a force which would force water to circulate.
It is identical and equal 70 ° With temperature on site AKIZ, therefore and here necessary force cannot be created. It is necessary to consider other two sites - AV and EZ. On site AV the water temperature is equal 95 ° With, and on site EZ it makes 70 ° S.Pri such parity of temperatures the necessary condition for occurrence of circulating pressure owing to a difference of scales of water on site EZ and AV is available and circulation in ring ABVGDLEZHZIK is created. Told concerns the top heating device.

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