Safety valve with pressure control: types
Hot water is an integral part of a person’s comfortable life. However, there are often situations when either hot water barely flows from the tap, or there is no central water supply in the region at all. In such cases, it is necessary to acquire a water heater, or in other words, a boiler. In it, water is heated by electricity. And therefore - there is a danger to others. This can be either an explosion of an overheated water tank or a short circuit. In any case, you need to take security measures to prevent trouble.
Safety valve device
If we consider the storage water heater in terms of design features, it is a sealed tank in which water is heated by heating elements. When heated, steam is formed, and accordingly, the pressure inside the tank increases. Therefore, among other characteristics of any water heater, there is necessarily an indicator of the maximum allowable pressure.Usually for domestic boilers, this figure hovers around 10 Bar.
During the day, family members constantly consume water - wash, take a bath, wash dishes. Hot water takes place cold. At night, when everyone is asleep, the water heater again heats the water, and at the same time the pressure rises inside its case. There is no return flow of water into the system, since the taps are closed and pressure accumulates in the tank.
When the heating temperature reaches the parameters set by the user, the device is turned off by the thermostat. The pressure in the pipes of water supply to the heater is about 2.7-3 Bars, steam heated by the boiler is added to it, and as a result, the pressure in the body of the water heater reaches 3.5-4 Bars. This situation is quite acceptable and is within regulatory limits.
Despite the presence of automation in water heaters, it is quite possible that the thermostat does not work for some reason. In these cases, the boiling point of water inside the boiler rises in proportion to the pressure. For water, this parameter is 180 degrees. If the tank contains about 80-100 liters, then all this volume turns into steam and the boiler body may not withstand such pressure, as a result of which an explosion occurs.
To prevent such explosions in the hot water system, safety valves with pressure control are installed. Their tasks are the following:
- discharge of excess pressure from the boiler in manual and automatic modes;
- prevent the outflow of fluid into the plumbing system in the case when there is no water.
The principle of the safety valve
In fact, two valves are combined in the body of the safety valve.
One is a check valve, which is located on the side from which cold water flows. With a full tank of the heater valve prevents the flow of excess water from the mains. As the tank becomes empty, the pressure inside the boiler drops, and the valve begins to let in fresh cold water. As soon as the internal tank of the boiler is filled with water, the valve closes again. A spring-adjustable seat inside the valve prevents water from flowing out from inside the heater back into the pipeline.
The second valve is safety. When the boiler is operating normally, the valve is closed. If an overpressure occurs, the valve outlet channel opens under the influence of the spring and the fluid is discharged until the pressure is equalized.At the same time, correct adjustment of pressure relief valve pressure is important. The valve and valve glass are usually made of brass, the best body is considered to be bronze.
Installation of safety valve
- The valve is installed on the water inlet of the heater, designed to introduce cold water. Mounting it, it is necessary to monitor the correct location. For this purpose, a special arrow is shown on the pressure relief valve body with pressure control, indicating the direction of water movement. It should point towards the heater.
- At independent installation of the valve it is necessary to watch that it is casual not to block its channel. On some boilers, installation limiters are provided that allow you to screw it all the way. If there is no such option, then the valve is wound by 3-4 turns.
- After installation is recommended to look from the cold water inside his body to see his saddle. When lightly pressed on it, it should slightly move forward, thereby freeing the way for water. After releasing the saddle should quickly return to its place.Otherwise, there is a clear mistake during installation and the valve should be reinstalled.
Important: in no case should you use a check valve instead of a safety valve. In this case, the excess pressure inside the tank will not be relieved, but the function of preventing the outflow of water back into the pipeline will only work.
Safety valve check
To test the safety valve with pressure control, close all hot water taps and do not touch them until the end of the test.
- On the panel of the boiler set the temperature of water heating at around 80 degrees.
- As the temperature rises, a valve should flow out of the valve nipple or drop of liquid. If this does not happen, then you need to wait for the heater to turn off the thermostat.
- Then you should again raise the heating temperature to the maximum possible.
- After heating the water to a new mark, the liquid should again appear from the nozzle.
- If the water does not flow out or the boiler is not able to set a higher heating temperature, then the valve will most likely need to be replaced.
- After checking the valve on the fitting, it is better to put on the hose, the other end of which is put into the sewer.
If the water from the safety valve begins to flow immediately after filling the tank with water, it is recommended to replace it.
Operation of the device without installed a safety valve for a boiler, the adjustment of which is not foreseen, is prohibited, because it is dangerous to others.
How to choose a safety valve
Choosing a safety valve with pressure regulation, one should proceed, first of all, from its response pressure and characteristics of the heater itself. The response parameter is indicated on the valve body or in the instructions. It is not recommended to purchase parts that do not provide for the adjustment of this limit of action.
The valve should also have a lever for forced, manual discharge of water. When external examination it should not be defective threaded connections.
Also important is the location of the fitting on the valve, since it should be convenient to put on the drain hose.
Possible faults and solutions
It is not uncommon for a liquid to flow out of the nozzle during a cold water heater. This suggests that, most likely, there are foreign objects in the valve. This may be dirt, scum and so on. In this case, you need to open the drain completely with a special lever and rinse the mechanism thoroughly with merging water. After the clear water begins to flow through the hose, the lever can be closed. After that, the flow from the choke should stop. Otherwise, the safety valve for the boiler should be replaced.
If fluid is constantly flowing from the valve, then the spring is most likely weakened. Have to buy a new valve. Another reason for such a malfunction may be the insufficient volume of the expansion tank or its malfunction. A solution to this problem would be to install an additional tank at the outlet of the boiler.
If all the taps in the system are intact, and the water does not come out of the valve hole at all, the mechanism should be flushed.
After installing the parts and turning on the boiler, it is necessary to adjust the safety valve. For this:
- After reaching the set temperature of water, turn the knob or the adjusting screw until water begins to flow out of the valve opening.
- Part of the water drains from the tank. Cold water will immediately take its place. Accordingly, the temperature of the water inside the boiler will also fall.
- Turn on the limiting heating mode of the water heater. In this case, the water from the nozzle should begin to flow. Otherwise, loosen the spring until fluid appears. Then one more test cycle should be carried out.
- After that, the operating mode of heating is set to 60 degrees. Excessive heat should not be exposed to save heat exchanger.
Steam safety valves are adjusted according to the same principle.
Safety valve service
Periodically required to flush the valve from scale, rust and foreign objects. This is done by opening the emergency reset channel with a lever.
It is not recommended to drain all the water using a safety valve, as suspensions at the bottom of the boiler can get on the spring and interfere with its normal operation.
With constant care for the part, the water heater will last much longer and there will be no dangerous situations during its operation.