How the heating system with natural circulation
works The heating system with natural circulation operates according to the physical principle: the expansion of the liquid when heated.
When the boiler heats the water, it expands and is displaced upwards by a smaller density. Then the water, gradually cooling down, passes through the circle of the system and returns to the boiler. Water, giving heat to heating appliances, cools down and its density again rises. Then this cycle is repeated.
Features of heating with natural circulation
- Large inertia. From the moment of ignition of the boiler and before warming up of all heated rooms, it may take several hours. Since water starts to move slowly through the pipes only after the heat exchanger warms up.
- In order for the water to be able to circulate freely and freely, all pipe sections are mounted under a slope along the water flow.
- Limited area of the heated building. Since the pressure difference is small, water can not effectively advance in pipes with a radius of more than 30 meters.
Heating system: operating principle
Heating with natural circulation is a self-regulating system. The fluid velocity varies from room temperature. The lower the temperature, the higher its speed. Also, the speed depends on the position of the boiler relative to the lower heater. The lower the radiator, the higher the speed.
Parameters influencing the velocity of the heat carrier
In addition to the already listed principles affecting the velocity of the coolant, there are other:
- The material from which the pipe is made.
- Pipe diameter. The smaller the inner diameter of the pipe, the greater the resistance it will provide. Therefore, it is necessary to choose pipes with a large cross-section( DN32-DN40).
- Number of turns and their radius.
- Availability and quantity of shut-off valves.
Power calculation methods: by area
The method of calculating the power by area is very simple. To determine only one parameter is needed - the area of the heated room. So for 10 m2 one kilowatt of power is needed. At the same time, it is necessary to take into account the amendment to the area of residence: 0.7-0.9 for the southern regions, 1.2-1.3 for the central strip of the country, and 1.5-2.0 for the regions of the Far North.
This method does not take into account such parameters as: ceiling height, heat leakage through openings, walls insulated.
By volume and taking into account additional parameters of
More accurate results are given by the calculation of capacity by volume.
At 1m3 it is necessary to take 40 watts of heat output. And take into account the coefficient of correction for the area of residence( the same as in the calculations for the area).Also to the received sum it is necessary to add on 100 watt on each window of the standard size and 200 watt on a door. Depending on the thickness and material of the walls, it is necessary to make an amendment from 1.1 to 1.3.And in private houses, another 1.5 on the uninsulated ceiling and floor.
Diagrams for wiring the heating system. Single-pipe layout
This type of wiring is a ring in which the coolant moves in a circle.
With this wiring, the fluid can move in two ways: split into a fluid going into the radiator and further along the riser, and not divide, and pass through all heat exchangers in its entirety. The second option is not very convenient in practice, as there is no possibility to adjust the temperature in the rooms with the help of cranes.
In order to maintain the same temperature in rooms located on different floors, it is necessary to take into account in the installation that the surface of the heating devices on the first floor should be larger than the second and subsequent ones.
Device of two-pipe system
In this variant of wiring, there are two mains: feeding, outgoing. With a two-pipe system, the elements of the heat network are connected in parallel. This allows you to adjust the temperature in each room.
With a two-pipe system, unlike a single-pipe system( top), the wiring may be done as the top, with the expansion tank at the highest point( attic spaces) and the lower one, having a hot line in the basement.
Conclusions
The heating system with natural circulation has several advantages: easy installation, quiet operation, independence from electricity, long working life. But there are also disadvantages: the limited area of the heated premises, the slow warming up of the house. Before you decide on this system, you need to carefully study the principle of work and weigh the pros and cons.
