Heating system

Different systems of space heating to maintain thermal comfort or for industrial purposes. The term is usually applied to systems in which combustion occurs in a more or less remote from the heated place, in contrast to the primitive hearth or stoves and small portable heaters.
Of the heating system.
Steam heating. Most heating systems, in which the coolant is steam, working on the principle of convection, i.e. they heat the air and thereby reduce to an acceptable level of heat loss. In systems of this type as the heating devices can be used cast iron radiators, convectors, is made usually from non-ferrous metals, or heaters. Advantages of steam as a coolant are high heat transfer capacity, relatively low weight and constant temperature in the heat transfer process. The latter circumstance is of great practical importance, since it ensures the same temperature on different parts of the heat transfer surfaces. Another (not so significant in conventional heating systems) advantage is high heat transfer coefficient in film condensation and therefore small thermal resistance in heat transfer through heat transfer surface. The disadvantages of steam systems are the difficulty of regulating the magnitude of the heat supply to the premises (this does not apply to systems with low pressure, etc. vacuum steam systems) and high temperature (100° C) at atmospheric pressure. Conventional steam system can be divided into the following types.

Open closed single tube system. This is the cheapest system of steam heating. They consist of one steam pipe connecting the steam boiler and heating appliances. The steam line is laid with a slight slope for condensate return by gravity to the heat source. In systems of this type for coolant going in two directions one tube so that its cross section should be large enough so that the steam flow was not carried away by a current towards the condensate. At the top of the pipe coming from the boiler is provided an exhaust device. A serious drawback of one-trumpet system is the inability to regulate heat flow; the heater can operate in fully open or fully closed instrument valve. Partial regulation is possible with the help of special devices, however, it is rarely cost-justified

Two-pipe steam system. In this system, increased consumption of pipes by the use of a separate return pipe to drain the condensate from heaters. Steam is supplied thereto through the control valve, and the condensate falls into the return line through thermostatic traps. In addition to the possibility of regulation, this system allows to avoid problems related to noise, which sometimes is a serious problem in single-pipe systems.
System with reduced pressure. In systems of this type regulation of the heat supply is carried out by changing the temperature of the steam exiting the steam generator, with a corresponding change of latent heat of condensation and the specific volume of the coolant. In this case regulation occurs at the level of the whole system in the steam generator, in contrast to the regulation of the individual radiator or convector in the double-tube high pressure system.

Water heating. Advantage water system before steam is mainly more simple regulation of the heat supply of the radiators and convectors. Classification of water heating systems under the scheme of location of the pipe risers is provided below.
One-pipe horizontal system. This system differs from the one-pipe steam systems because the water in the pipes flows in the same direction, and the minimum length of pipelines is assured by the fact that the water after passing through the heaters is returned to the feed system. Thus, the flow in the delivery pipe is constant along its length, and the temperature drops, due to flow of colder water from the heating devices; therefore, for a fixed teplopodachi area of the heat-transfer surface of the heater must increase with increasing distance from the heater.

Single-pipe vertical system. For buildings with more than one floor, usually use a variation of the single-tube system with the top distributing and laying on the attic of the flow line, from which extend downwards parallel to the vertical risers to supply water to radiators that are located on different floors strictly one above the other. The temperature of the water in the delivery pipe is the same at the entry point to any downside of the riser; a temperature change occurs only in the risers.

Two-pipe system. The location of the pipes in this system is similar to two-pipe steam system. The water from the heater passes through the supply pipe with wiring to a separate radiator, and coming out of them, water gets into the return pipe, which returns it to the heater. Diameter flow and return piping is reduced as the distance from the heater. The drawback of this scheme is that the loss of pressure in each hydraulic circuit (depending on each radiator) grow as the distance from the heater, therefore, to ensure equal flow through heaters need to take special measures.
Deadlock two-pipe vertical system. This system is similar to the vertical one-pipe system except that the radiators on each floor are connected in parallel between the inlet and outlet risers.

Flow two-pipe system with passing movement of water. This hydraulic circuit has all the advantages of two-pipe systems and at the same time is devoid of the drawback associated with the inequality of the pressure drops inherent in dead-end schemes. Hot water from the heater passes through the supply pipe of decreasing size, from which extend pipes to heating appliances, and from them in the return pipe, which runs parallel to the supply pipe from the water heater collecting emerging from the radiator water and increasing in diameter until the last radiator; the length of the path traversed by water, is the same for all radiators. Deadlock two-pipe system with a counter movement of water in supply and return distribution piping and two-pipe gravity system with passing movement of water is shown for comparison in Fig. 2. The water heater is marked with the letter H, and the radiators – numbers.

Radiators and convectors. As heating devices in the heating systems of the convection type are generally used cast iron radiators or convectors, is made from steel or nonferrous metals. Conventional radiators are composed of cast-iron sections connected to the battery using nozzles with left and right thread. Radiators are typically installed along the walls of the heated space. Most often they are placed under Windows to prevent cold air flow from the Windows to the floor. Standard cast iron radiators available in sections of different width and height. Usually, this section consists of several interconnected vertically arranged pipes, the number of which depends on the width of the section. Air enters the radiator from the bottom and front and, when heated, rises, runs along the radiator and out the top and heated with a noticeable speed. Convectors differ from radiators that have much smaller heating surfaces and are arranged in the lower part of the casing, which is needed to create the effect of “chimney” to arrange the movement of air past the heating surface and then to distribute the flow of heated air the volume of the room. Characteristics of the casing of the convector depends on the size and position of holes for air inlet, and the chosen method of blowing heating surface.

System heaters. For convective heating systems are also used in industrial premises of the system with a tubular heater through which a fan with great speed is blown into the room air. Under conditions of forced convection in such a system the heat transfer from the heating surface is more intense than for conventional convector or radiator, so the heating efficiency is significantly higher compared to other systems. The heaters are normally executed in the form of a unit mounted near the ceiling in the center of heated space. The casing of the heater has louvers that allow you to change the direction of flow of heated air to provide better mixing of the air and prevent the formation of undesirable stagnant zones with a temperature gradient (Fig. 3).

Tubular heaters with a developed surface heating sometimes used in the input channels of air heating systems instead of directly ognevozdushnyh heating. The problem of choosing the right heater and its rational allocation is the well-known difficulties, because the efficiency of the heater depends on many factors, in particular, from its location in the room and air flow directions at the inlet and outlet.

System with Underfloor heating. In areas where the climate is mild and therefore heat loss from the room is small, often used cheap heating system with a gas heater located in the basement. While cool room air, dropping to the air heater, passes its outer heated surfaces and returns to the room through a built-in floor grating. Heaters of this type is fully Autonomous, have low cost and can be easily installed. However, they are not free from drawbacks, which include the danger of excessive heating of the surface of floors and the difficulty of providing uniform heating of the living space.

17 Photos of the Heating system