You can test your water heater pressure relief valve by opening it slightly with a bucket underneath to catch dripping water. Don't force the valve open if you feel resistance. You'll know that your valve is working properly if you can see or hear water and gas escaping.
Excessive noise: If your hot water heater is rattling or emitting a high-pitched whistling noise, it's likely the sound of steam trying to escape the tank, which is a sign of far too much pressure pressing against the inner walls. This means the relief valve isn't doing its job and may need replacing.
Leaking and Strange Noises
PRV valve leaking usually means there's a hole in your valve. If you see pressure relief valve leaking, flooding, or if you hear strange noises coming from your PRV, it's time for a replacement.
If you notice excessive noises coming from your unit, there's a problem. Two common water heater sounds are rattling and whistling, both of which result from built-up steam that can't escape the unit. If the steam can't escape properly, that means the pressure relief valve isn't working.
Contaminants, like dirt, lint, rust, sludge, or even the misalignment of the valve can cause the pressure relief valve to stick. At this point, you might see that your system is above pressure, or you'll notice other pressure relief valves in the system releasing to make up for this valve's malfunction.
Under normal conditions, the useful safe service life of a pressure relief valve is 10 years from the original date of manufacture. However, the safe useful life of the valve may be shortened by certain environmental conditions and other factors. At times, replacement may be necessary much sooner.
Once the valve releases the pressure, it can be reset within seconds by moving the reset handle.
WARNING: Under normal conditions, the useful safe service life of a pressure relief valve is 10 years from the original date of manufacture. However, the safe useful life of the valve may be shortened and replacement required in less than 10 years depending on the environment in which the valve lives.
If your water heater pressure relief valve is working, this is when it will open. This releases steam and hot water from the discharge tube, making your water heater operate safely again.
The valve opens when the pressure inside the tank exceeds the preset limit, usually 150 psi (pounds per square inch), or the temperature goes above 210 degrees Fahrenheit.
To open the valve, you simply flip the lever up. After doing this, hot water will flow into the pipe and out into the discharge spot. Opening the valve on occasion will help ensure that it is working properly. Opening it will also help release any excess pressure that is built up inside the tank.
A relief valve opens when static upstream pressure is higher than the opening pressure, and it opens in proportion to the pressure increase. This type of valve is more often used with incompressible fluids.
A pressure relief valve regulates pressure increases in a functioning system. A pressure safety valve rapidly reduces the system's pressure to a safe operating level.
In operation, the pressure relief valve remains normally closed until pressures upstream reaches the desired set pressure. The valve will crack open when the set pressure is reached, and continue to open further, allowing more flow as over pressure increases.
A safety valve is a pressure relief device used to prevent the over-pressurization of a system. On the other hand, a relief valve is a device used to relieve pressure from a system that is already overpressurized. The function of a pressure relief valve is to protect a system or component from excess pressure.
Pressure relief valve replacement costs an average of $220 between parts and labor, or anywhere from $50 to $300.
Pressure Relief Valve – $20 to $200
If you notice that the valve is consistently leaking, it may mean that the tank's pressure is too high, or you might simply have a faulty/clogged valve. The cost of a new pressure relief valve is about $20, and repairs may total to $200.
When an undersized expansion tank is installed in a system the volume of water will be more than it is designed to handle. This will cause an increase in system pressure; triggering the relief valve to open in order to prevent damage to the pipeline.
Since the pressure relief valve vents at the top of the tank, you could wait until the tank is full before closing it, but it's better to close it when you start refilling the tank in case you forget.
If the PRV is improperly adjusted, or has failed, it can result in a pressure loss or even no water downstream.
Pressure relief valves sometime develop a drip when opened for the first time in years. Try opening and closing it a few times to see if it will seat itself. If you have a large leak or the drip doesn't stop on its own in a day or two, the valve will need to be replaced.
The price of pressure reducing valves starts at around $50. You can expect to pay around $350 for a professional plumber to install a new pressure reducing valve.
The most common cause of high pressure in a hot water heater is the excessive buildup of steam or air within the tank.