During the operation of the heating system, the volume of the coolant inevitably decreases. In open circuits this process is faster, in closed circuits it is much slower. When the critical level of drop is reached, the efficiency is significantly reduced, and emergencies may also occur. To minimize such risks, the heating system needs to be fed: valves, pumps, units and circuits are selected according to a specific type of system.
Basic rules for arranging heating make-up
What is the reason for the decrease in the volume of water in the pipes? The main source of its leakage is the excess of the operating temperature. As a result, a critical expansion of the liquid occurs, after which its excess in the form of vapor leaves through the air vent (closed circuit) or an open expansion tank (gravitational).
The installed automatic make-up of the heating system compensates for the lack of water by adding the required volume to the line. But this is not the only case when the prompt addition of the coolant to the system is required:
- Removing air plugs. As a result of opening the Mayevsky valve or air vent, some of the liquid will inevitably leave the system. In a closed circuit, in this case, a pressure drop will occur, to which the automatic make-up of the heating system should respond;
- Micro leaks. Loose pipe joints and loss of sealing even at a small level will lead to a gradual decrease in the volume of water. It is difficult to identify such defects, but it is necessary. The automatic make-up valve of the heating system will only work after the pressure has dropped to a minimum level;
- Carrying out repair or maintenance work;
- The formation of corrosion on the walls of metal pipes, which leads to their thinning and, as a result, an increase in the internal volume. At first glance, this is an insignificant factor. But if the feeding of a closed heating system is not installed, the pressure will gradually decrease and air locks will begin to form.
What should the heating system make-up device consist of? It all depends on the type of heating circuit. Also, the design of adding a coolant to the system is influenced by its characteristics: pressure, temperature mode of operation, line diagram, number of heating circuits, etc.
For the central system, a refill unit with a pump must not be installed. This will lead to a change in the parameters of the entire circuit, which will affect the efficiency of work.
Make-up of an open heating system
The peculiarity of an open or gravitational heating system is the absence of increased pressure in the pipes. Therefore, an improved design of the expansion tank can be an indicator of a decrease in water in the system. It should be located at the highest point of the line.
In this case, the replenishment of the heating system of a private house is carried out only when the liquid level in the tank decreases. This will be signaled by the lack of water pressure in the control pipe. Usually its outlet is installed in the bathroom or in the kitchen. To prevent a constant flow, a shut-off valve is installed - a tap.If there is no flow during control opening, the system must be filled with water.
To do this, you need the next element of replenishment of the heating system for a private house - a node connecting the highway to the water supply.
Structurally, the assembly should consist of the following elements:
- Ball valve - designed to open (close) the supply of tap water to heating;
- Filter... Since the quality of water does not always meet the requirements, it is necessary to clean it from impurities and debris. Subsequently, they will become the main reason for the formation of limescale;
- Check valve - prevents the movement of water from the system into the water supply. This situation can happen in the absence of water in the water supply line.
With this circuit, you can make up a closed heating system. However, an air vent must first be installed to remove excess air. For the correct addition of water, it is necessary that the heating medium heating level be minimal. This is especially true for systems with natural circulation. There is a high probability of the return movement of the cold liquid to the operating boiler. This can lead to damage to the heat exchanger due to the sudden temperature drop.
The simplest device for replenishing the heating system can consist of a conventional storage tank. However, in this case, the liquid level in it will have to be monitored visually.
Make-up of a closed heating system
For a closed system with increased pressure, the above scheme will not work. In this case, it is necessary to install an automatic make-up of the heating system. The principle of its operation is to add a coolant when the pressure indicator decreases below the minimum level. You can make the simplest scheme yourself. It includes a ball valve, a pressure gauge and a pressure reducer for the heating system. The latter is the main element in this system. The principle of its operation needs to be told in more detail.
It consists of the following components:
- Regulating block with spring on the stem and diaphragm. Located at the top of the structure;
- Stop pad to restrict the flow of liquid from the make-up pipe;
- A non-return valve that prevents the flow of coolant into the water supply system.
Using the regulating block, the value of the minimum pressure in the heating system is set. In this case, the coolant acts on the membrane, preventing the stem from dropping down. As soon as the pressure drops below the critical level, the stem will drop under the action of the spring. Thus, the damper will open and water from the water supply pipe will flow to the heating. After the pressure has returned to normal, the stem will return to its original state and the fluid flow will stop.
Installation of the heating system make-up reducer is carried out on the return pipe before entering the boiler, for further heating the water in the heat exchanger. This is due to the minimum value of the internal pressure in this section of the system. If a circulation pump is provided in the system, the installation of the automatic make-up of the heating system is carried out in front of it. Otherwise, during the operation of the pump, surges in the pressure of the coolant are possible, which will lead to a false operation of the pressure reducing valve.
To regulate the flow rate of water to make up the heating system, a valve with a locking platform must be used. In this case, the volume of water passing can be from 5 to 12 l / min, depending on the set value.
Possible problems when feeding a closed system
At first glance, such an automatic make-up unit for the heating system is ideal for a closed system with forced water circulation. However, in the practical application of the block, you may encounter the following problems.
Reduced pressure in the water supply
According to the standards, the pressure level in the water supply network should not exceed 4 atm. The same value for heating is usually no more than 3 atm. Those. theoretically, when the valve seat is opened, a high-pressure flow from the water supply will flow into the heating main. However, in practice this does not always happen. This is especially true for autonomous water supply systems. If the pressure in the water pipe is lower than in the heating pipe, the coolant will not flow, but will decrease from the system.
To solve this problem, it is necessary to install a check valve, and also a pump to feed the heating system is required. The latter will create the required level of pressure in the supply line. To turn it on, you will need to install a few more additional elements along with the heating system make-up valve:
- Pressure gauges with switching relays connected to the pump;
- Pressure relief valve opening sensor;
- Storage tank.
This unit of automatic feeding of the heating system will work as follows. If the valve opening sensor is triggered and the pressure on the pressure gauge is below the critical one, the circulation pump is automatically turned on to feed the heating system. In the absence of water in the water supply system, it will come from the storage tank.
Membrane sticking
This problem is typical for long-term operation without turning on the automatic make-up of the heating system. Regardless of the material of manufacture, slight limescale deposits will appear on the inner walls of the gear unit. It will prevent the valve from opening, leading to an emergency.
To avoid this, before starting the system, and then at least once a month, open the stem manually. This will make it possible to make sure that the system is working, and will also help prevent a critical drop in the level of hot water in pipes and radiators.
It is best to use stainless components to organize the make-up of the heating system. Valves, pumps, units installed according to the scheme will then last much longer. Brass products are somewhat inferior in their performance to stainless steel.
Installation and packaging tips
The normal operation of the machine for replenishing the heating system largely depends on the installed elements and its location on the diagram. It is necessary to repeat once again that the assembly of the unit should be carried out only on the heating return pipe. Otherwise, false alarms of the system are possible, which is incorrect.
Bypass
In the automatic make-up of any heating system, breakdowns of individual components are possible. There is a likelihood of a decrease in the coolant or the impossibility of adding it to the pipeline in another way. Therefore, the unit should be installed on a bypass.
With such a make-up scheme, during its breakdown or the need for preventive maintenance, it is possible to manually supplement the heating system. However, this must be done very carefully, since there is a high probability of exceeding the critical volume of water in pipes and radiators, which will lead to a sharp increase in pressure.
Procedure:
- We close the stopcocks on the mains of the heating system make-up valve.
- We open the shut-off valves on the bypass, ensuring the flow of water.
- We monitor the value on the pressure gauge, which is located not on the feed line of a closed system, but after it directly in front of the pump or boiler.
- As soon as the pressure reaches the desired level (from 1.5 to 3 atm.) - we shut off the bypass valves.
Before performing these actions, you need to suspend the heating of the water so that its temperature drops to a minimum level. Otherwise, the probability of failure of the heating boiler increases.
Filtration
Since the above schemes provide for the addition of tap water, it is necessary to provide for the installation of a filter system. By default, almost all gearboxes for feeding the heating system are equipped with mesh elements. However, they are designed only for the retention of foreign impurities of a large fraction. It is best to install a complete pre-cleaning system for the coolant.
In this case, you can purchase a household kit for drinking water purification, since it performs the required functions. At the same time, the operation of the automatic make-up unit for the heating system will be much more efficient:
- The likelihood of limescale deposits on pipes and radiators will be reduced;
- The percentage of air in the liquid will decrease, which will have a beneficial effect on the absence of corrosive processes;
- The frequency of mandatory flushing of the heating system will increase.
Following these rules, you can not only optimize the water consumption for feeding the heating system, but also increase the efficiency. If antifreeze is used in heating, it is necessary to add a storage tank with it to the make-up circuit of a private house system. With the help of an additional pump, the coolant will be supplied to the system. It is important to constantly monitor the level of antifreeze and replenish it periodically.
In the video, you can familiarize yourself with an interesting scheme for feeding heating in the presence of an indirect heating boiler:
