Safety valve for the boiler – protection against explosion

In a person’s home, having hot water is a convenient and enjoyable feature. However, there are instances in which there is neither a central communication system nor a barely warm liquid flow. A water heater must be purchased. Electricity and nearly boiling liquid are combined in this device. As such, precautions have to be taken to avoid harm.

Purpose

A storage-type heater’s tank is a hermetically sealed reservoir that holds heated water. Vapor is produced and pressure increases during this process. For this reason, the unit has a maximum pressure indicator among its technical features. In most cases, 10 bar is used for household appliances.

The hot water runs out and the tank fills with cold water after every family member has taken a bath, shower, and cleaned the dishes in the evening. The water heater heats the water while people are sleeping, which increases the pressure inside the casing. There is no backflow into the system and all taps are closed. Consequently, the boiler’s internal pressure increases.

Upon attaining the predetermined heating threshold, typically between 60° and 65°, the thermoregulator ought to deactivate the device. Simultaneously, there is 2.7–3 bar of pressure in the water supply system and approximately 4 bar of pressure in the heater’s body due to the steam generated by the heated tank. Everything is within normal bounds.

Assume for the moment that the sensor has not been activated. Physics states that the boiling point increases with increasing pressure. 180 degrees Celsius is the parameter for water at 10 bar. About 80–100 liters of liquid were once inside the tank; now, all of that mass has condensed into steam. There will be an explosion if the casing breaks. In this case, the boiler’s safety valve can provide protection. There are two purposes for this mechanism:

1. It prevents spontaneous drainage of liquid from the heater into the system when there is no water in the utilities.
2. Releases overpressure from the tank in automatic and manual modes.

Operating principle

Two valves are housed in one housing.

• The first check valve is located on the cold water supply side. As the tank is emptied, the pressure in the water supply becomes higher than in the tank and the inflow pressure pushes the seat away from the inlet port. Clears the path for water to enter the boiler. When the appliance is full and the pressure in the appliance and the pipes equalizes, the spring returns the seat back into place, thus blocking the outlet from the boiler back to the water supply network.
• The second, safety valve for the boiler, is closed during normal operation of the appliance, but in case of overpressure, the jet from the unit acts on the valve, the calibrated spring is pressed and the outlet channel is opened to discharge the excess liquid.

Installation

1. The device is mounted directly on the inlet pipe of the water heater.
2. The direction of fluid flow must be observed during connection. For this purpose, there is an arrow on the valve body, which should point towards the boiler.
3. Some models may have an internal setting stop. This safety valve can be screwed onto the boiler as far as it will go. If this option is not available, then screwing the mechanism should be made no more than 4 turns. Violation of this rule may result in narrowing of the safety channel.
4. With the mechanism mounted on the heater, look inside the heater casing on the cold water side of the heater. The seat of the check valve should be visible. Try pressing it lightly with a blunt object. If installed correctly, the barrier should feed forward and return to its original position when released. If the seat does not move, the work has been carried out incorrectly.

Caution! A basic check valve should not be used in place of a boiler safety valve. Only the tank empty warning feature will function in this situation. There will be no release of the excess pressure.

Checking

It will take several hours to finish this procedure. Throughout the duration of the test, the hot water taps cannot be opened.

• Once the heater is fully connected and filled with water, set the control panel to a heating limit of about 80 o"clock on the control panel .
• As the temperature rises, close to the maximum, a trickle or drops of liquid should appear from the connection.
• If this does not happen, wait for the thermostat to turn off the water heater.
• Depending on the specifications of your model, raise the limit to the highest possible limit.
• When the heating process is finished, liquid should drip out. If there is no leakage, or if the appliance is able to reach a level of more than 80 o, it is recommended to have the valve checked in a workshop or to replace it with a new safety mechanism.
• Put a hose over the connection of the defective mechanism and secure it with a hose clamp. The second end must be led into the sewer.
• In the case when water starts to flow immediately after filling the tank the device is defective, it must be replaced with a new mechanism.

It is not permitted to operate the boiler if the safety relief valve is not installed.

Selection

The primary guideline to follow when selecting this device is the match between the mechanism’s pressure and the heater’s specifications. The housing or the documents that go with it specify this parameter. It is preferable to avoid purchasing models with predetermined action limits.

Take note that a forced drain lever is present. Verify the quality and absence of thread defects by inspecting the threaded connections.

The location of the drain plug should make it easy to attach a hose to it.

Possible faults and remedies

1. If water leaks out of the emergency drain hole when the boiler is cold, it means that foreign matter has probably gotten into the valve. Open the drain fully with the lever and allow the liquid to flush the mechanism abundantly. When clean, clear liquid flows through the hose, close the outlet with the lever. The flow should stop, otherwise the unit should be replaced.
2. Water is constantly leaking from the valve. Such a failure indicates that the spring pressing the seat has become loose. Since this part is a calibrated part, a new valve must be purchased. An extraneous cause of this trouble can be a significant increase in pressure in the cold water supply system, but this is unlikely and will be noticeable when using other plumbing appliances. Unfortunately, there is another possibility of this defect – the absence or insufficient volume of the expansion tank in the boiler. The best option to eliminate the problem is to replace the water heater with another manufacturer"s product. If this solution is not possible, install an additional expansion tank at the outlet of the heater.
3. If there is no liquid coming out of the connection at all, and all taps are in good working order and there are no leaks in the hot water distribution system – flush the device as described in p. 3.1 or replace the mechanism.

Adjustment

Once you’ve bought a manual boiler safety valve, install the device following the above instructions.

• Perform a complete installation, connection and filling of the water heater.
• Turn the appliance on close to the maximum setting according to the manufacturer"s instructions.
• As soon as the set temperature is reached, turn the adjusting screw or knob, depending on the valve model, until water starts to flow out of the connection.
• Drain some of the liquid from the tank. This will free up space in the tank, which will fill with cold water. Consequently, the temperature inside the heater will drop. Once again, turn on the boiler"s limit mode. Water will now flow out of the discharge channel automatically. If this does not happen, loosen the spring until a thin trickle appears. Check with another cycle of draining and reheating.
• Set the operating mode to about 60 o"clock . It is not advisable to constantly use higher temperature settings unless absolutely necessary. This can provoke increased wear of the heat exchanger.

Maintenance

The boiler safety valve needs to be flushed during use in order to get rid of scale, rust particles from the pipes, and other foreign objects in the water, depending on how much hot water is used. This requires periodically using a lever to open the emergency drain channel.

The water heater should not be emptied using this mechanism. Particles that fall to the bottom of the tank and get trapped there after going through the bleed spring will stop the system from working correctly.

We stress the vital role safety valves play in averting boiler explosions in our article "Safety Valve for Your Boiler: Protection Against Explosions." An essential part that relieves excess pressure and protects both your boiler and your house from possible hazards is the safety valve. Homeowners can successfully shield their families and property from the risks associated with boiler explosions by being aware of how safety valves operate and making sure they are installed and maintained correctly.

You can use hot water safely and confidently by making sure the safety valve is functioning properly and by adhering to all usage guidelines for the water heater.