Boiler Pressure Relief Valve Keeps Going Off [7 Easy Fixes]

A common problem that users with household heating systems encounter is that the boiler pressure relief valve keeps going off. The issue of the pressure relief valve often occurs due to a defected relief valve, clogged expansion tank, or a faulty heater coil.

In addition to these, malfunctioning thermostats, defective fill valves, damaged aquastat, and relief valve leakage issues also play major roles in the pressure relief valve blowing off. So, continue reading to know the solution to these problems.

Boiler Pressure Relief Valve Keeps Going Off [7 Easy Fixes]

There are 7 possible reasons that result in the water heater pressure relief valve blowing off. Here, we will discuss each and every reason in detail along with their solutions.

Note: You can also read the Utica Boiler troubleshooting guide.

1. Defected Relief Valve

The issue with the heater relief valve blowing off often occurs when the relief valve is faulty or damaged in any way.

If the pressure relief valve is faulty, then it will leak water and cause a flood around the water heater, resulting in an expensive repair.

How To Fix It:

Turn off the water heater and allow the water to cool down and reach its normal temperature.

Drain all the water from the heater and remove the discharge tube from the system as well. Examine the relief valve properly to identify the defect.

Replace the pressure relief valve with a new one and make sure that it is set correctly. Turn on the water heater and fill the tank to ensure that the valve is working perfectly.

2. Clogged Expansion Tank

Water and air get trapped in the water heater expansion tank over time and use. This trapped air and water cause an increase in pressure inside the tank which causes the pressure relief valve to go off.

How To Fix It:

Turn on the water heater and keep a close eye on the pressure gauge. If you notice that the pressure is rising at an alarming rate while the water is in the expansion tank, then you have a clogged expansion tank.

Turn off the heater and release all the water from the heater after cooling it down. Repair or replace the expansion tank and turn on the water heater. Check the pressure once again and check if the pressure relief valve is leaking or not.

3. Faulty Heater Coil

The heater coil inside the water heater heats up the water and over time, it develops a defect or stops working due to the accumulation of dirt.

This faulty heater coil forces the pressure into the boiler which in turn results in the pressure relief valve blowing off.

How To Fix It:

Switch off the water flow to the heater coil and keep an eye on the pressure gauge. If the pressure continues to increase even if the water flow is turned off, then the issue is with the heater coil.

Clean the heater coil of all water impurities and repair the defect. Turn on the heater and ensure that the pressure is at the correct level.

However, due to the sensitivity or danger regarding the internal parts of the water heater, we recommend the help of a professional in cases like these.

4. Malfunctioning Thermostat

The issue of the relief valve blowing off often occurs when the water temperature inside the heater is too high.

The thermostat setting often malfunctions, causing the water to overheat and generate an immense amount of pressure. The relief valve then blows off to release the excess pressure from the water heater.

How To Fix It:

Examine the thermostat and make sure that it is working properly. Check the water temperature and pressure to ensure that it is not overheating.

Repair the thermostat and make sure to turn off the water heater before working on the thermostat. Turn the heater back on and adjust the temperature set properly.

5. Defective Fill Valve

To ensure a safe functioning water heater, the fill valve of the heater is designed to reach a maximum pressure of 12psi.

However, defects in the fill valve often cause the boiler pressure relief valve psi to reach 30 or more. This causes the relief valve to go off and leak water, causing a flood around the heater.

How To Fix It:

Turn off the water heater and allow the water inside to cool down. Continue to drain the water until the pressure drops down below 12. Keep an eye on the water pressure and make sure that it doesn’t increase.

Replace the fill valve if the pressure continues to increase even after draining the water. Turn the heater back on and check the pressure once again.

6. Damaged Aquastat

The relief valve often goes off when the water temperature reaches too high. This happens when the aquastat inside the water heater gets damaged or defective and fails to control the temperature of the water.

How To Fix It:

Turn off the boiler and drain all the water once it has cooled down. Examine the aquastat properly and make sure that it is functioning accurately.

Repair or replace the defective aquastat with a new one and turn on the boiler. Make sure that the water is heating up at the right temperature.

7. Relief Valve Leakage

Last but not least, leakage in the relief valve is a common cause of the pressure relief valve going off.

The relief valve opens to let all the excess pressure out of the system in order to ensure proper performance. However, leakage in the valve will cause water to leak continuously, flooding the floor.

How To Fix It:

Turn off the heater properly and check the relief valve to make sure that there are no leakages. Repair or replace the valve and the pipe connected to it. Turn the heater back on and ensure that the relief valve is working properly.

How To Replace The Pressure Relief Valve

Replacing the pressure relief valve is highly important when it encounters a leakage or becomes faulty.

Now, there are a few steps that you need to follow in order to replace the valve. Here, we will discuss the steps on how to replace the pressure relief valve properly and easily. 

Step 1: Disconnect The Boiler

The very first of replacing the pressure relief valve is to disconnect the main connection to the boiler in order to stop the water from heating up.

Make sure that you switch off the connection to the water fill valve as well to stop the water from filling the boiler. Let the boiler cool down and wait for the temperature of the water to drop. 

Step 2: Drain The Boiler

Once the water has cooled down completely, turn on the boiler tap and drain all the water stored inside.

This step is essential in order to drop the boiler pressure to zero. Continue draining water until the pressure reading reaches zero. 

Step 3: Replace The Valve

The next step is to remove the faulty or leaking pressure relief valve from the boiler with the help of a pipe wrench.

Put the new pressure relief valve in place and tighten it properly in position. Make sure that the relief valve is placed in the proper position and will not come off. 

Note: If there is a drainage pipe connected to the valve, then disconnect the pipe before removing the old valve. Make sure to reconnect the valve after putting the new one in place. 

Step 4: Check The Valve

Last but not least, turn on the main connection to the boiler and the fill valve. Allow water to fill the boiler and heat up to check whether the valve is working properly or not.

Make sure that there are no leaks or any other issues with the pressure relief valve. 

FAQ:

How Often Should I Replace The Boiler Pressure Relief Valve?

The pressure relief valve must be replaced once every five years. However, replace or repair the valve immediately if you notice any damage or leakage.

How Much Does It Cost To Replace A Pressure Relief Valve On A Boiler?

The cost of replacing a pressure relief valve is about $20 to $40, depending on the model of the water heater. Replacing the valve professionally will cost significantly more money. 

How To Maintain A Water Heater Properly?

Check the water heater parts on a regular basis to ensure proper performance. Keep the temperature and pressure in check and make sure that it is within the limit.

Conclusion

Solving the relief valve blowing-off issue immediately is essential to prevent major problems in the future. At the end of the guide, you now know the reasons why the boiler pressure relief valve keeps going off and how to solve them.

Take help from the guide and solve the issue on your own whenever you encounter a blowing pressure relief valve.

If you have any questions about the water heater or pressure relief valve, leave a comment below. We will respond to your query soon with the best possible answer.