Incorrect operation, surges and pressure drops can cause malfunctioning of the heating system. The consequences of situations of this type are critical: breakage of parts, destruction of a structure, a serious threat to human life. A simple safety valve in the heating system will help to avoid unsafe risks. Therefore, it is worthwhile to understand their varieties, the principle of action, the features of the choice.
Operating principle
The main valve element is a steel spring. Due to its own elasticity, it controls the pressure on the only membrane that blocks the external outlet. The membrane is located in the saddle and is supported by a spring, the end of which rests against a metal washer. It is securely fixed on the stem, attached to a plastic lever.
The safety valve for heating works as follows:
- Under normal conditions, the membrane is in the seat, completely blocks the passage.
- As soon as the coolant overheats, it begins to expand, creating increased pressure in a closed hydraulic system. The latter is often compensated by an expansion tank.
- If the value of the backwater rises to the value of the valve actuation (most often 3 bar), the spring is compressed, the diaphragm opens the passage. The boiling coolant is automatically dumped until the spring closes the passage hole.
- In the event of a breakdown, the excess pressure can be relieved manually. Then you should turn the handle at the top of the safety mechanism.
The discharge mechanism is installed on the main section not far from the heating unit. The recommended distance is 0.5 m.
If the boiler operates at high power (the coolant temperature reaches 95 ° C), then the operation of the protective device happens cyclically. This has an extremely negative effect on the safety device: due to loss of tightness, it leaks.
Varieties of valves
The following types of mechanisms are suitable for installation in a heating system:
Reset
According to the principle of the simplest safety device, a relief valve for heating functions: the gases or heat carrier formed, after reaching the overpressure limit, press on the membrane and leave the system.
Lever-cargo
Suitable for pipes with a diameter of 0.2 m and larger. In heating systems in which the heat source is a boiler, lever-cargo valves are not installed. These mechanisms use a weight to increase the effect on the membrane. In order to determine the pressure force, upon reaching which the valve is put into operation, adjustment is carried out by changing the weight of the load.
Back
An emergency device of this type is mounted to relieve excessive pressure. Additionally, it allows the coolant to move through the pipes only in one flow, determined by the project.
Spring loaded
The most demanded device used for an autonomous heating system. The device is durable, simple design: the stem is pressed by a spring. Adjust the parameters of the device triggering with a possibly present control mechanism.The force of impact is determined by the degree of compression.
Ball
It has a very simple design: the hole is closed with an ordinary steel ball (by weight force). The opening pressure of the valve is calculated in advance, it directly depends on the diameter of the hole and the weight of the ball.
Air
The purpose of such a valve is to free the system from the gases that form, which create traffic jams and prevent the heating from working properly.
Valve Installation Requirements
The device for removing excessive water pressure is installed taking into account the expansion tank in the heating system. The safety valve is triggered after the volume of the diaphragm tank is exhausted. The mechanism is placed on a pipeline connected to the boiler nozzle. The approximate distance is 20 - 30 cm.
In this case, it is imperative that the following conditions be met:
- If the valve is installed separately from the safety group, it is first necessary to install a pressure gauge in order to monitor the pressure.
- Do not install gate valves, taps, pumps between the valve and the heating unit.
- A pipe is connected to the valve (outlet pipe) to drain the excess coolant.
- It is recommended to install the protective mechanism at the highest point of the heat carrier circulation system.
- The protection device needs to be replaced after seven to eight operations due to loss of tightness.
The safety relief valve of the heating system is an important element of autonomous closed-type heating, completely regardless of the type of boiler. Even if the latter includes its own security group, experts recommend installing another one on the circuit itself.
Recommendations when choosing
Before purchasing specific safety equipment, it is required to study in detail the technical parameters of the boiler plant. It is highly recommended that you carefully read the manufacturer's instructions for the boundary parameters of the equipment.
The following criteria play a major role in the selection of the required valve:
- heating unit performance;
- allowable pressure in the system for the heat output of the heating equipment;
- valve diameter.
In addition to the above, it is necessary to check that the pressure regulator of the protective mechanism has a range suitable for the parameters of the heating unit. The response pressure should exceed the operating value of the normal functioning of the system by 25-30%.
The valve diameter must match the size of the inlet. Otherwise, under the influence of hydraulic resistance, the valve will not be able to fully perform its functions.
It's not bad if the device is made of brass. It has a small coefficient of thermal expansion. This characteristic excludes the destruction of the body under excessive pressure. The control unit is made of materials that are resistant to high temperatures, which retain the required rigidity even in case of contact with boiling water.
Reasons for valve actuation
A working safety device will never go off without a reason. Each actuation of the valve must be examined to determine the provoking factor. There may be several of them. Although they are not always serious, everyone is subject to verification.
- Unstable operation or failure of the heating boiler thermoregulation system. The alarms are usually frequent, the water spill is abundant.
- Expansion vessel problems. This may be the initial setup. Hidden reasons: malfunction of the nipple, breakage of the membrane. In such cases, there are sudden pressure surges in the system, which leads to short and frequent valve openings.
- The limit value of the pressure in the heating system. The defense mechanism leaks slightly.Such manifestations are present, since the accuracy of the spring device is ± 20%. To avoid such situations, you should more accurately configure the system and select the appropriate equipment.
- Valve wear. After several trips, the performance of the protective device decreases. Therefore, it is better to replace it with a new one or repair it.
- Malfunction of the spring. This happens over time, even in the absence of alarms. Sometimes undermining occurs as a result of coolant seeping around the stem. Repair or replacement cannot be avoided under similar circumstances.
You can check the health of the safety valve using the red handle. If you turn it clockwise, water should appear on the normal valve. The leak stops immediately after the crank stops rotating. If this does not happen, you need to twist again. When this does not help, the replacement of the protective device will be required.
The safety device for pressure regulation is considered to be quite reliable due to its design features. On the eve of the choice, first of all, you need to pay attention to the quality characteristics of the material, you should not buy a cheap product. Correct setting of the valve according to the permissible boiler pressure is very important.
