In our country, autonomous heating systems are often used to heat country houses. They represent rather complex constructively communications, in addition to the boiler and radiators, which include many other elements. For example, in such networks, an expansion tank is installed next to the heat generator. For a closed heating system, the volume of such an expansion tank must be calculated without fail. Otherwise, the expansion tank will not cope with its functions.
What is a closed heating system
It is these networks for heating country houses that are most often used in our time. Closed heating systems differ from open ones in the form of an installed expansion tank. This element of home networks is mounted at the highest point and is responsible for stabilizing the coolant pressure in the pipes.
When heated above +4 °C, water, as you know, begins to expand. The same thing happens to her with strong cooling. Therefore, the pressure in the pipelines of heating systems is not constant. When the coolant expands, the pipes can simply break. To prevent this from happening, an expansion tank is installed in the network. With an increase in the volume of the coolant, its excess simply goes inside it.
Types of expansion tanks in home heating networks can be used differently. If this device has an open design, the system is accordingly called open. If the expansion tank on the line is mounted sealed, the network is called closed.
Benefits
The main advantage of a closed expansion tank in the heating system is that, if it is available, a circulation pump can also be included in the design of the latter. This allows you to make an autonomous network much more productive and easy to use. In addition, the structural elements of such heating systems do not spoil the appearance of the premises of the house. In this case, thin pipes are connected to the boiler.
In open systems, water moves along the highways by gravity - under the influence of gravitational forces. Such networks are considered non-volatile. However, during their installation, thick pipes are laid around the house, which, of course, negatively affects the appearance of the premises. In addition, such heating systems cannot be installed in buildings of a large area. Are being built todaythe city is mostly large private houses.
Types of expansion tanks
The installation of structural elements of this type of heating system must be carried out correctly. Only in this case, the network will eventually turn out to be reliable, easy to use and last a long time. And first of all, for a closed heating system, of course, you need to choose the right expansion tank.
First of all, you should purchase such a device, designed specifically for heating systems. These tanks are red. On sale today there are also blue expansion tanks designed for hot water pipes. Such a tank for a home network used for space heating will not work.
There are three main types of expansion tanks for closed-type heating systems on sale today:
- membrane type;
- embedded inside the heat generator;
- vacuum.
Membrane tanks
Such containers, in turn, are now available on the market in two versions:
- diaphragm;
- balloon type.
Both of these types of membrane tanks have similar technical and operational characteristics. The difference between them lies only in the fact that the volume of the expansion tank for the closed heating system of the last variety is slightly larger. Accordingly, more coolant can fit into it.
The membrane itself in the cisterns of both varieties is shaped like a pear. On the opposite side of it, air or nitrogen is pumped under some pressure into such an expansion tank.
These tanks work according to a very simple principle. With an increase in pressure in the network, the tank membrane stretches and launches water into it. When the pressure drops, everything happens in the reverse order.
Built-in cisterns
Such containers are usually used with wall-mounted gas boilers. Expansion tanks are most often included directly in the design of such heating units. The advantage of containers of this type is, first of all, the complete absence of contact with the external environment. Diffusion of oxygen into the coolant in the presence of such a tank cannot occur.
Some drawback of this type of tanks is not too long membrane life. It usually falls into disrepair after 10 years of operation. At the same time, it is not always possible to replace it.
Vacuum containers
Compensation structures of this type differ in that they do not have a pear inside. The role of the membrane in them is played by the air itself. Such tanks are used very rarely in home heating systems. The fact is that they are almost impossible to find on sale. In addition, such tanks are also not considered too convenient to use and reliable.
Calculating the volume of the expansion tank of the heating system
It is necessary, of course, not only to select an expansion tank for the heating system, but also focusing on its volume. Before the purchaseof such a compensation device, it is imperative to make its calculation.
There are several methods for determining the required volume of an expansion tank for a heating system. But when installing such networks on their own in small houses, property owners usually use simplified technology.
Based on the laws of physics, experts have established the fact that at maximum heating, the water in the mains of home heating networks expands by about 5%. Accordingly, the required volume of the expansion tank for a closed heating system can be calculated as follows:
- in accordance with the passport of the heat generator determine the amount of coolant in the pipes;
- find the throughput of pipes (by multiplying the cross-sectional area by the length);
- determine the amount of water in the radiators from their passport;
- sum up all three found values.
When using this technique, the tank is chosen with a margin not of 5% of the result obtained, but just in case of 10%.
Where to install
After the volume of the expansion tank for a closed heating system is determined, and this device itself is purchased, the owners of a country house will need to choose the most suitable installation location for it.
Such a container, as already mentioned, should be mounted at the highest point of the system. Expansion tanks are currentlyin most cases, they are installed directly in the boiler room next to the heating unit.
Mount such devices usually on the return pipe in front of the pump (in order to exclude water hammer). In principle, the feed is also a suitable place to install a closed expansion tank for a heating system. The amount of coolant in such networks is usually uniform. But, since the temperature of the water at the supply is significant, a container mounted in this way will serve here in the future, most likely, not for too long.
Installer tips
Experienced craftsmen recommend inserting an expansion tank into the heating system through a flanged or screwed connection. In this case, later the tank can be easily removed for repair.
You cannot install filters or check valves on the branch that connects the tank to the main. When choosing a tank installation site, experts also recommend making sure that it will be completely free here. No pressure from the structural elements of the heating system or anything else should be exerted on it.
The closed expansion tank will function, even if lying on its side. But embedding it into the heating system, of course, is better vertically.
Installing an expansion tank in a heating system: installation steps
The expansion tank is usually inserted into the system as follows:
- capacity is securely fixed on the floor or on the wall;
- mark the shortest route for the pipe to the connection point;
- stretch the pipe and connect the tank.
On the connection to the tank, among other things, they usually install a simple inexpensive ball valve. This allows you to cut off the tank from the system at any time and drain the water from it.
