Safety valve for heating system
The water heating system includes several groups of elements. And some of them the inhabitants do not attach much importance. Take, for example, a safety group consisting of a heating system safety valve and an expansion tank. It may seem that both elements do not play the most important role. But you can't do without them. It is not for nothing that they were assigned to the security group, which means that special attention should be paid to their selection and proper installation.
Consider each device separately and find out why it is needed and what functions are assigned to it.
Safety valve
The name of the device speaks for itself. Its main function is to relieve unforeseen loads that may arise under certain circumstances. Plus additional adjustment of the coolant flow.
By the way, it can be installed on any section of the pipeline. At the same time, it is not the place that is important, but the convenience of service, if such a need suddenly arises.
Types of safety valves
- The simplest option is brass sleeve fuses. Their design is simple - threads are cut on both sides, and the valve is a spring-loaded stem with an EPDM gasket. This is a direct-flow model, the valve of which opens under the pressure of the coolant flow. Back pressure closes the line. This is one of the cheapest devices, but it lasts a very long time, which is time-tested.
- There is another brass version, but with a more complex design, where the pipes are connected in perpendicular planes. It uses a stainless steel stem and spring. Install it directly after the circulation pump. The principle of operation of such a device is quite simple. The pressure of the coolant compresses the spring, which begins to put pressure on the rod. He opens the channel through which the coolant is squeezed out of the system, saving it from pipe ruptures and other elements. By the way, the maximum temperature that the valve can withstand is 120C.
- There are a large number of varieties of check valves, which are also included in the safety group. Their main function is to prevent the backflow of the coolant from occurring if the pressure suddenly drops in the system.
There are several main types - disk, ball, flag and others. But they are all divided into spring-loaded and springless. With the first, everything is clear - there the main emphasis is on the counteraction force of the spring. The second type is when the return of the locking element occurs under the action of its own mass.
- Three way valves. This type of valves is installed in heating systems where low-temperature circuits are provided. For example, when there is a condensing boiler in the circuit. Currently, manufacturers produce this type of valve with manual or electric switching. In the second case, it is necessary to connect the device to an alternating current network with a voltage of 220 volts.
Three way valves
Let's take a closer look at three-way valves, because consumers rarely encounter them, and they are simply unknown to many. There are three holes in their design - two outlets and one inlet. The coolant flow is regulated by a damper, which can be in the form of a rod or a ball. The rotational movement redistributes the flow of the moving fluid.
We have already mentioned condensing boilers, but three-way valves are not only used in these systems. Very often they are used when different heating systems operate from one heating boiler. For example, "warm floors" and conventional radiators. It is clear that for a warm floor it is not necessary to heat the coolant to a very high temperature. But what if there is only one boiler, and it heats hot water to the standard temperature for the entire system?
In this case, the three-way valve performs several functions at once:
- First, it separates the plots.
- Secondly, it delimits the flow density by branches.
- Thirdly, with its help, the heat carrier is mixed from the supply and return lines, before the latter is supplied to the “warm floor” heating system. That is, water will flow into underfloor heating at a lower temperature than to radiators.
A few recommendations. Get a servo model. This will relieve you of the need for constant monitoring of the temperature of the coolant. Such a device is automatic and operates from a sensor mounted in a low-temperature circuit. A change in temperature entails the operation of a shut-off device that opens or closes the water supply from the return line. So everything is simple.
And the last. The actuator may be included with the valve or sold as a separate item. And the valves themselves are made of steel, cast iron or brass. The latter are used in residential heating systems.
Expansion tank
Indirect heating boilers with expansion tank
First, let's find out what it is. This is a small container that is built into the heating system and filled with air. It is designed to relieve the pressure of the coolant when it expands when heated.
There are two main systems that are directly connected to the expansion tank - open and closed. An open system is used if the coolant in the heating circulates naturally. That is, there is direct contact of hot water with air. The point of contact is the expansion tank.
In this case, the expansion tank performs two functions at once:
- Hides the expanding volume of the heated coolant.
- Allows you to remove the air that accumulates in the heating system. That is why in an open circuit all lines are made at a slight angle.
The closed system is characterized by complete sealing of the joints. The tank in this case is no exception. It works for its intended purpose, that is, it contains an increasing volume of hot water. And what will happen if the pressure limit of the tank suddenly exceeds the maximum? The system from closed will become open, that is, somewhere there will be a break. It can be a pipe or the same tank.
Both designs have very serious differences. For example, it is a container with a lid. But the latter plays the role of a cover from debris and in no way provides sealing. In addition, this design does not save the coolant from evaporation, so it is periodically added. The closed version is a sealed container with a membrane inside. It is she who creates a barrier that does not let oxygen into the heating system of a private house.
As you can see, the selection of an expansion tank is not as difficult as it might seem at first glance. Here it is important to consider the type of heating system and the volume of the coolant. After all, it is believed that the volume of the expansion tank should be about 10% of the total volume of the coolant.
Where to install the expansion tank
Where to install the tank for the system
This is not the most difficult question, but still there are some nuances in it. If your house has an open heating system with natural circulation of the coolant, then the expansion tank is installed above all other heating elements.
In a closed system, the tank can be located in the area where the circulation pump is installed. Thus, the issue of the laminar pressure indicator is solved, since it is in this area that it is the largest. But in the case of air outlet, this tank does not play a role. Yes, and in a closed system it does not matter. But if problems still arise, they can be solved by installing Mayevsky cranes on radiators.
- It has been said more than once that the volume of the expansion tank should be equal to 1/10 of the volume of the coolant. Of course, sometimes it is difficult to accurately determine the last indicator, so an approximate calculation is carried out, to which a few percent of the stock is added.
- In closed tanks there is already a slight pressure that is created in the factory. It is equal to 1.5 kg / cm 2. The pressure in the heating system reaches two atmospheres (kg / cm 2). You can increase the pressure in the tank by pumping air into it through a special nipple, which is present in the design of the tank.
- On sale today you can find tanks of different colors. The red ones are for heating, and the blue ones are for plumbing.
- Installation is carried out in such a way that the coolant enters it from above. In this way, air can be prevented from entering the piping system.
- If the installed safety valve works very often, then you made a mistake with the tank volume in the smaller direction. But do not immediately dismantle it and change it to a new larger volume. You just need to install another smaller one next to it.
- In modern gas boilers, especially wall-mounted ones, expansion tanks are already included. Therefore, before purchasing the latter, make sure it is available or not.
Another question that is often heard on construction forums concerns the manufacture of do-it-yourself expansion tanks. There are no objections to this. It is only important to correctly observe the parameters of the tank. But remember that homemade containers can only be installed in an open heating system. They can be made from metal sheets or plastic containers with thick walls. The main thing - no leaks at the joints.
Expansion tank boiled
Heating system with pump circulation
This is already a serious matter. This sometimes happens if amateurs are engaged in the installation of the heating system.
There are two reasons:
- Incorrectly selected diameter of the pipe of the main line. It must be at least 32 millimeters. It is optimal if the radiators crash without breaking the line, but are connected in parallel to it.
- If there is no slope of the branches. Usually, a so-called accelerating collector is installed after the boiler. A vertical riser rises from it, on which an expansion tank is installed. All other highways are laid at a slight angle. If something is broken, the tank will surely boil.
What to do if this problem arose, and the alteration is too costly or does not want to be carried out? Option one - install a circulation pump on the return line near the boiler. He will feel great in an open heating system.
Conclusion on the topic
As you can see, the safety group is a necessary element that directly affects not only the operation of heating, but also the efficiency indicator. Eliminate one of them, and you will have a box of problems that cannot be solved in other ways. And if possible, it is very expensive.