One of the most important parameters of the heating system is the preservation of the direction of movement of the flow of the coolant. For this, it is necessary to provide for the installation of special fittings. First you need to choose a check valve for heating: ball, petal, schemes for their installation. Having found out the design and operational features, you can choose the optimal model.
Check valve requirements
During the operation of the heating system, a difference in hydrodynamic pressure inevitably occurs in certain areas. One of the consequences of this phenomenon will be a change in the direction of the flow of hot water. By installing a bypass check valve for heating, you can avoid an emergency situation and achieve stable operation of the entire system.
What is this device like? Its main task is to prevent the reverse movement of the coolant. It is important to choose the right check valve for the heating system: petal, spring disc or ball. But first, let's consider the causes of the emergency:
- Uneven cooling of the coolant in the gravitational heating system. If the expansion rate of water in the return pipe is greater than in the main pipe, the probability of a change in flow is high;
- Several heating circuits. In this case, it is problematic to ensure uniform pressure inside each of them. Therefore, the fluid will move along the path of least resistance, which is not always the right direction. Example, connecting a water heated floor with a mixing unit. If you do not install a check ball valve for heating, then the flow of hot coolant may not flow into the distribution manifold, but into the return pipe;
- Completion of a bypass - an intermediate line between the direct and return pipelines for uniform distribution of heat energy over the radiators in the system.
Based on these requirements, the check valve of the heating battery must ensure the unhindered passage of hot water, prevent its reverse movement and not affect the technical and operational characteristics of the system. The latter is considered an impossible task, since in the course of hot water flow, the valve will create additional hydraulic resistance. That is why the choice of a particular model must be approached more than scrupulously.
The installation of a check valve on the heating bypass can be done in any spatial orientation. Regardless of the angle of inclination of the structure, it will perform its functions. But this only applies to spring models.
Check valve selection parameters
Regardless of whether a petal check valve for heating or a ball valve was chosen, you first need to decide on its connection parameters to the pipeline. The basic rule is to match the bore diameter of the reinforcement of the entire line. Those. if the cross-section of the cuts is 32 mm, then this parameter for the valve should be the same.
Then you need to select the type of connection to the system. The following models of check valves are currently on the market:
- Coupling... With threaded connection.A similar scheme is used for a spring-loaded disc check valve mounted in an autonomous heating of a private house or apartment. The maximum size usually does not exceed DU-50;
- Flanged... Designed for installation on lines of large diameters - from 50 and above. The most commonly used is a ball check valve for heating;
- Interflanged... They are mounted between pipe flanges and are characterized by small dimensions. The best choice is a petal check valve for district heating.
For systems with pipes of small diameters, spring-type threaded coupling models are most often mounted. They are characterized by simplicity of design and reliability. But at the same time, you need to pay attention to the material of manufacture. It is best to install stainless steel check valves for the heating system. They are able to withstand pressure up to 10 atm., The surface is practically not subject to rusting. However, their cost is the highest, which is due to the peculiarities of manufacturing.
Brass valves are less reliable, but they are quite suitable for a home autonomous heating system. This material rusts very slowly, but compared to stainless steel it has a lower mechanical strength. Often, a ball check valve for heating with a diameter of up to 32 mm is designed for a maximum pressure of 5 atm.
For central heating, the best option is to install cast iron products. Despite their massiveness and high weight, they can withstand critical pressure values, which is one of the mandatory parameters of valves of this class. Alas, the specifics of manufacturing do not allow the production of cast iron check valves for heating systems with a diameter of less than 40 mm.
After deciding whether a check valve is needed in the heating system, you can proceed to the choice. Let's consider the main design features and installation conditions for each of them.
For a one-pipe heating system with one circuit, a check valve is often not needed. The only exceptions are bypasses for radiators, where its installation is required.
Ball check valve for heating
A truly universal ball check valve for heating is considered. To create a locking mechanism, a sphere is used in it, which, under the action of the coolant flow, rises into a special end pipe. If the pressure level decreases or the movement stops altogether, the ball goes down, blocking the entire passage. Moreover, its diameter should be equal to the cross-section of the pipe. The advantage of using such a mechanism is its reliability. There are no moving parts or other mechanisms in the design. The chance of breakage of the ball heating check valve is very low.
However, you need to take into account its operational features:
- High cost due to the complexity of manufacturing;
- The working diameter can vary from DN15 to DN This makes it almost impossible to install them in an autonomous heating system of a private house for a pipeline with a small cross-section up to 40 mm;
- The minimum pressure to raise the ball is typically 25 bar.
Given this specificity, in the overwhelming majority of cases, they make the installation of a check ball valve for centralized heating when laying large highways. Exceptions are autonomous systems with a high pressure indicator - industrial and commercial.
Models with a rubberized ball have proven themselves best. No limescale forms on it, and a protective shell protects the metal from corrosion.
Lobe check valve for heating
Due to the shortcomings of the above-described model, another type of shut-off and control valves was developed - one or two-leaf petal check valve for heating.Steel plastic is used as the main mechanism for regulating the direction of fluid flow. The system of hinges ensures free movement of the shutters under the action of the pressure of the coolant.
Depending on the design, there are two types of petal check valves for heating - two-leaf and rotary. In the first case, the pivot axis is located in the middle of the line, and steel plates are installed on its sides, which serve as the shutters. In models, the valve is mounted on a special internal platform. In this case, hydrodynamic losses will be minimal.
Flap-type two-leaf check valves are often manufactured with a wafer-type fastening, as their design allows installation with the minimum allowable pipe clearances.
Swivel flap-type models are most often made of cast iron alloy for pipelines of large diameters - from 50 mm.
Installing a petal model will ensure maximum pipeline throughput in this section. This applies in particular to the pivoting structure.
Spring loaded disc valve
For an autonomous system of a country house or apartment, another check valve is needed for heating. The pipe diagram for them rarely provides for the installation of large cross-sectional lines. Therefore, all the above models cannot be installed due to dimensions and limitations on the mounting diameter. As an alternative, the spring-loaded check valve, which is also installed on radiators, has proven itself well.
For its operation, a central rod with a spring is provided, which abuts against a disc stop. Under the action of the pressure of hot water, the disc is displaced and the coolant flows further along the line, in case of a change in the direction of flow, the seat does not allow the liquid to flow in the opposite direction.
The advantages of installing this type of check valve are as follows:
- Large selection of mounting diameters - from 16 to 40 mm;
- Low cost;
- Coupling method of connection to the system, which is the most acceptable for private autonomous heating.
The disadvantage of a spring-loaded valve is the possibility of scale build-up on the disc and its seizure after a long period of inactivity. This will lead to the formation of an artificial plug in this section of the pipeline, which will prevent water from circulating further along the heating circuit.
Before purchasing, you need to pay attention to the material of manufacture of the stock. For heating, you should buy models with a brass or steel core.
Check valve installation
Where in the line do you need a check valve in the heating system? All types of bypasses for radiators and boilers are compulsorily equipped with them. Also, a ball check valve for centralized heating is installed at the branch points of the pipeline.
When installing autonomous heating when installing a spring valve, you need to pay attention to the following nuances.
- The direction of movement of the coolant must be indicated on the body;
- To improve waterproofing, you need to use special paronite gaskets or winding. But they should not artificially reduce the working section of the shut-off valves.
In addition, a non-return valve for heating is used for a water-heated floor system. It is mounted on the return pipe for mixing with hot water.
It is best to purchase stainless steel spring loaded valves. Their average cost ranges from 125 to 750 rubles, depending on the diameter. Brass models have proven themselves well for low temperature heating systems.
The video material clearly shows an example of the operation of a check valve in a heating system.
