Everyone is familiar with natural selection, but this is also relevant in relation to the numerous inventions of mankind. With the passage of time, something like that they pass too. Some technologies will sink into the abyss, remaining forever forgotten, while others become classics that are immortal and out of competition. As for the latter, here we can also include a heating system with natural circulation (CO with EC). Despite the availability of more advanced and functional solutions, the technology still remains in demand; it has successfully passed the test of time.
Features of natural circulation
This system has other names: thermosiphon, gravity, gravity.
It includes several components:
- Heat generator (boiler, stove or fireplace with a water jacket).
- Closed loop - pipes, radiators filled with liquid coolant (water, oil, antifreeze).
- Expansion tank.
- Shut-off and control valves.
- Instrumentation.
The heated coolant from the furnace or boiler moves in a closed circuit, heating the radiators. And those, in turn, transmit energy to the surrounding air in the room. The main feature of this system is precisely in a special way that provides the movement of the coolant.
Residents of residential buildings are noticeably lighter, as the apartments have central heating. Owners of private real estate objects have to establish water heating with natural circulation for their home independently. But how does the system in question work? This is described below.
Operating principle
As we know from the school bench, if the medium is heated, its volume will increase according to the known laws of physics. Moreover, from the colder part, the force of Archimedes begins to act on it, forcing it to rise.
This phenomenon also has its own name - convection. It is it that acts as the “power unit” of the coolant, where the concept of “natural circulation” appears. And since convection is closely related to gravity, the system is still called gravitational.
The power of convection flow largely depends on the temperature difference between the coolant heated in the boiler or furnace and in the area coming in (return). As you can understand, the pumping of the working medium is carried out without using a pump. And this implies that the heating system of a one-story house with natural circulation does not need electricity, that is, it is non-volatile. And since there is no electrical appliance, the savings are obvious.
In other words, when heating water (usually it is used as the heat carrier) it loses its density and rises along the central riser, pushed by a cold stream that returns to the boiler. After that, hot water is sent to the radiators through the supply pipes. Giving heat, it is cooled and gravity goes back to the heat generator (return) and the cycle is repeated countless times.
In addition, since there is no pump, then excessive pressure will not arise. Therefore, as an expansion tank, an open tank is sufficient. Its presence is due to the fact that a constant pressure is maintained in the heating system.
Significant factors
But what affects the water speed in the heating system with the natural circulation of a single-story house? As a rule, this is due to the following factors:
- The magnitude of the circulation pressure - the greater it is, the better.
- Diameter of pipelines - a small section will create more resistance to water flow than a larger diameter. In this regard, the dimensions for the wiring are usually from 32 to 40 mm.
- Pipeline material - modern polypropylene solutions are less resistant when compared to metal pipes.
- Contour turns - ideally when the pipeline is straight.
- The number of fittings, adapters, retaining washers - here there are limitations, since each valve reduces the degree of pressure.
To create the optimum pressure in the heating system with EC, the boiler must be placed as low as possible of the circuit system. This is usually a basement. For obvious reasons, the expansion tank is installed as high as possible and in most cases is located in the attic.
It should be borne in mind that the heating system of the house with natural circulation has an inert character, which means it proceeds rather slowly. The duration from ignition of the boiler to complete stabilization of the temperature regime takes several hours.
Coolant options
As a rule, it is customary to use water or antifreeze as a coolant. But since the latter has a higher density and low heat dissipation, it will take much more time to heat it, and therefore, fuel. In this regard, it is many times more profitable to use water.
In addition, when heating antifreeze, it expands much more. As a result, when choosing this coolant, the expansion tank should be even larger than with water.
Advantages of heating system with EC
The key benefits of heating a home with natural circulation are:
- Low cost due to the lack of an expensive circulation pump.
- No noise. Even the most modern pumps produce a quiet hum - during the day you can not hear it against the background of ambient noise, but at night you can hear the buzz, which causes discomfort.
- Pump malfunctions result in additional costs.
- The number of breakdowns is minimal - there is practically nothing to break here, with the exception of the boiler. Leaks are quite rare and can be easily fixed on their own.
But the main advantage of the heating system with the EC lies precisely in its non-volatility. In areas where there are constant power outages, this is the best option.
Explicit Cons
Yes, and such a seemingly perfect heating system of a one-story house with natural circulation, which works according to all the laws of physics, has a number of disadvantages.
The obvious disadvantages include:
- Small radius of the coolant.
- Inability to regulate the temperature in each room separately.
- Water circulates around the circuit under slight pressure, which causes a noticeable decrease in temperature - the farther the radiator from the boiler, the lower it is.
- A long period for the system to enter full mode of operation.
- Since the expansion tank is located in a cold attic space (which is often not heated), there is a likelihood of the coolant freezing.
Despite all these negative aspects, heating from the EC is still relevant. Perhaps this is due to the fact that for many people, the benefits outweigh all the disadvantages above.
Varieties of heating circuits
The natural circulation water heating system can be performed according to one of several schemes:
- single tube;
- two-pipe;
- radiation.
At the same time, general parameters such as loop length, number of batteries, and a number of others do not play a special role. However, there may be many more specific schemes. However, below we consider only the simplest of them.
Single pipe line
This is the simplest scheme where one pipe is used to supply water to the radiators. However, in some cases, you can do without them, since the heat is provided due to the area of ​​the pipelines themselves.
If the scheme still implies the presence of radiators, then it is necessary to carry out the correct calculations of the number of batteries (sections). The optimal amount is not more than 5. Indeed, as the water passes through each point, it cools. In addition, as little as possible shutoff valves should be used in the heating system in a private house with natural circulation. In this case, the length of the circuit itself does not need to be greatly reduced.
The ideal option in this case is a diagonal arrangement. In other words, the coolant will flow into the radiators from above, redirecting to each point. After the last battery, the cooled water will be returned back to the boiler through a discharge pipe called a return. Moreover, the entire pipeline is one and the same, which, in fact, is the whole essence of the single-pipe line.
Double pipe system
This scheme is arranged a little more complicated, but also has its advantages. Here, the hot coolant is distributed through the batteries through one pipeline, and in the cooled state it returns to the boiler through another line. The result is improved heat transfer efficiency from batteries connected to one horizontal branch. Typically, the supply line extends along the ceiling or is located in the attic. As for the return, it is located above the floor.
Despite the obvious advantage of a single highway (minimum materials, therefore, minimum costs), a two-pipe heating system with natural circulation of a two-story house (or one-story) will still be the optimal solution. Moreover, divided into two branches with the same number of radiators.
Moreover, each battery receives a coolant with the same temperature, which is a plus, and very important! In addition, there is an opportunity for its automatic regulation, since the devices are independent of each other. Based on the aforementioned advantages of a one-pipe scheme, the disadvantage of a two-pipe system follows - increased material consumption. This is especially true for two-story houses.
Features of the beam scheme
In this case, the inlet and outlet line is connected to a special collector. In fact, this is a distribution comb, in which each branch is equipped with a throttle. In this case, two pipes are supplied to each battery.
Judging from the point of view of regulating the temperature regime, such a heating system with natural circulation is the most convenient. At the same time, installation works here are more complicated, since too many pipes are used. Therefore, in order not to spoil the appearance of the room, they are cleaned to the floor or hidden behind the false walls. And this already leads to a significant increase in the cost of work.
Features the construction of CO with EC
Since the work of CO with the EC is based on natural physical laws (a heated environment creates an upward flow), the batteries should be located above the level of the boiler. Optimum location - basement or ground floor. If there is neither one nor the other, then a correspondingly sized recess is made in the floor to install the heat generator.
Moreover, this is true not only for a private house, but also for apartments with independent heating. A small area of ​​the floor is cut off along with the screed so that the heating boiler with natural circulation can be installed directly on the floor slab.
For better natural circulation of the coolant, an accelerating manifold or a vertical pipe section is required, which originates from the boiler and rises to the very ceiling. Subsequently, the premises make a descent from the main highway to the radiators.
The minimum height of the booster manifold must be at least 1,500 mm, while it should be borne in mind that there should be free space between the upper trunk and the ceiling to accommodate the expansion tank. And as we know, this is an indispensable element of the entire heating system. If the house has low ceilings, then the tank is just cleaned in the attic, and these rooms need to be insulated. You can make a closed heating system using a membrane expansion tank, which can be installed in any convenient place.
It is worth noting that a closed heating system with natural circulation has its advantages:
- Heat losses are significantly reduced through the expansion tank.
- A closed system does not require regular airing.
- The volume of the expansion tank also decreases, the same goes for the thermal inertia of the system.
As you can understand, the presence of the second floor in the house significantly increases the efficiency of the booster.
For this reason, it is much easier to organize the natural circulation of the coolant in a two-story mansion than in a one-story house.
Rules for installing a heating system with EC
If there is a desire or need to organize a heating system with the EC, then a number of rules should be taken into account:
- The horizontal branches of the pipelines of the circuit must be inclined in the direction of movement of the coolant. Up to 10 mm on an extended highway and up to 50 mm in short sections per meter.
- In the process of creating a heating system with natural circulation by one's own hands, one should try by all possible means to lower the hydraulic resistance of the circuit. This rule should be followed when choosing batteries - cast-iron radiators are the best choice due to the small clearance.
- Polymer pipes have the smallest degree of hydraulic resistance. In addition, they do not overgrow with scale. But it is better not to use metal-plastic options, since the cross-section is noticeably reduced due to fittings. The best choice is polypropylene pipes, their working temperature is 70 °. Options made of cross-linked polyethylene are even more preferable - their temperature threshold is 95 ° C.
- If there are branches in the heating circuit, then after each of them the pipe diameter is selected one size smaller. For the return, the opposite is true - the size increases.
Since the concept of a heating system with natural circulation implies the absence of the use of electricity, the boiler must also be non-volatile. And such models are made by many manufacturers.
Among foreign companies, Bertta, Stropuva, ​​Buderus can be noted. But Russian companies can offer good options - "Energy", "Spark", "Conord".
Conclusion
As you can see, a heating system with an EC coolant has its advantages and disadvantages. Someone will like this option, and they will want to implement it. Others see in it only cons. In any case, such a natural circulation heating scheme suits many homeowners.
Moreover, most of them put a circulation pump on the return pipe to increase the efficiency of the heating system. Only it is located on the bypass. Such a measure allows you to transfer the circuit to gravity by opening a special tap when the power is turned off.