hot water heater safety valve leaking in stock

Temperature pressure relief valves play a vital role in protecting the safety of your water heater and your home. So when the relief valve starts leaking, Bay Area homeowners can be quite concerned. Today we’re going to answer the question, “Why is my water heater’s relief valve leaking?” and explain what you should do if it happens in your home!

When water is heated up inside of a water heater, thermal expansion causes the pressure inside of the tank to build up. If that pressure gets too high, your water heater runs the risk of exploding!

The temperature pressure relief valve is a safety mechanism that’s used to avoid this problem. If the temperature‘s  or pressure in your tank exceeds a certain level (often times 210 degrees and 150 psi), the relief valve opens up and allows some water to drain out of the tank. Cold water is then added to the tank in order to lower the temperature and pressure inside.

Your water heater’s relief valve can start leaking for one of two reasons: either the valve was triggered to open because of excessive temperature or pressure, or the valve itself is faulty. In the first case, the valve will drain water out of the discharge pipe as explained above. This may seem like a “leak,” but it’s really just the relief valve doing its job.

If the problem is a faulty valve, then you might have an actual leak. The valve might not seal properly, for instance, or the valve can get stuck and remain open (allowing water to continuously drain out).

No matter what caused your relief valve to start leaking, you should contact a professional plumber like Cabrillo as soon as possible. If the valve is frequently being triggered, we can determine why the temperature or pressure is getting too high in your water heater and fix the problem. If the valve has a leak, we can replace it with a new relief valve (a very common water heater repair).

If you have any questions about why your water heater’s relief valve is leaking, or if you’d like a plumbing system serviced or installed in your home, contact Cabrillo, your Bay Area plumbing, heating and air conditioning contractor.

The water heater is known for its high heat and high pressure. The water heater temperature-pressure relief valve (TPR Valve), protects us from this high heat and pressure. So what is the TPR valve, why does it leak, and what should you do about it?

The TPR valve, also called, a pressure relief valve is a specialized valve at your water heater. This valve is typically on the top or side of your water heater.

The valve functions by releasing water if your water heater becomes too pressurized. Since heated water expands, the water heater can become a ticking time bomb if we were to continually build pressure in your water heater.

As seen in the featured image, a TPR valve is required to have a discharge pipe/tube. This tube should be aimed straight to the ground and never go up. This is because hot water will come out of the TPR valve as it releases water. Therefore, extremely hot water should discharge to the ground for safety.

Additionally, if a pipe were to go up, water will have to work against gravity to empty. So, it is possible a slow drip of the TPR valve will collect water in the tubing and ultimately rust out the valve rather than empty it to the floor.

Be one nominal size larger than the size of the relief valve outlet, where the relief valve discharge piping is installed with insert fittings. The outlet end of such tubing shall be fastened in place.

Typically, the solution to this is through a bladder tank, also named an expansion tank. The expansion tank works by allowing more room for the heated water to expand too. Depending on your location and home, an expansion tank might be required by code.

However, if you find the relief valve to continue to leak even after replacement, you should contact a plumber for assistance. A licensed plumber will be able to evaluate your system and decide on installing an expansion tank or other solutions.

Water heaters come equipped with a temperature and pressure relief valve, also known as a TPRV. This valve allows water or steam to escape from the water heater if the temperature or pressure gets too high. This prevents a water heater from exploding or turning into a missile.

When a TPRV at a water heater leaks, it’s usually a simple fix; just replace the valve. These valves cost less than $15 and replacing the valve is a basic job. There are plenty of videos on YouTube showing how to do this, and the whole project probably won’t take more than fifteen minutes.

If you replace a TPRV and it starts leaking again, it probably means the valve is doing its job; it’s relieving excess pressure. When this happens, the fix gets a little bit more involved, and some troubleshooting is in order.

The TPRV on a water heater is set to discharge at 150 PSI or 210° Fahrenheit.  These numbers will be printed right on the valve, or on a tag attached to the valve.  See below.

If a pressure relief valve for a boiler is accidentally installed on a water heater, it will leak like crazy from the start. These valves may look identical, but they’re set to go off at 30 psi, not 150 psi.

The easiest way to do this is to get a gauge with a garden hose thread, connect it to an outside garden hose faucet, and open up the faucet. If that’s not an option, you can also use the hot or cold spigot for a washing machine. You should expect the pressure to be somewhere in the 40 – 80 PSI range with no other water running. If the pressure is over 80 PSI, it should be corrected. That’s too high for your system. The solution is to have a pressure regulator installed. Get a plumber to do that, as they’ll need to install an expansion tank at the same time. I’ll come back to those in a minute.

If the pressure is within the acceptable range, you probably have an intermittent problem with excessive pressure that can be easily re-created. Go run a bunch of hot water at your plumbing fixtures until you’ve exhausted the hot water supply on your water heater, and keep running the water for another few minutes. If you have several fixtures open, this should only take about ten to fifteen minutes. Now stop running water at all of your fixtures and wait.

You’ve just replaced the hot water in your water heater with cold water, which will cause your water heater to run for a while. This will cause the water to expand significantly until the water heater thermostat is satisfied. That might take about an hour or two. In most situations, this water will expand back out through the cold water inlet, all the way back to the water supply coming into the house. The municipal water supply for the house acts as a gigantic expansion tank… and nobody notices. This is illustrated in the diagram below.

A closed system exists when water can’t leave your house. One way for this to happen is to have a check valve installed on the water supply coming into the home. I don’t see a lot of these in Minnesota, but I do see them periodically.

The other way to create a closed system is to have a pressure regulator installed that contains a built-in check valve. With either of these installed, water can’t leave the house. When water expands and can’t go anywhere, pressure in the system increases. Watch your pressure gauge to verify this. Once the pressure gets to 150 PSI, the TPRV should do its job and leak.

When a closed system exists on the water distribution piping in a home, an expansion tank needs to be installed somewhere on the plumbing system. This is a simple and straightforward fix; an expansion tank will give the water somewhere to go when it expands, and the TPRV on the water heater will stop causing problems.

Expansion tanks are required when a closed system exists, both by water heater manufacturers and by plumbing codes. The Minnesota State Plumbing Code requires an expansion tank when a pressure regulator is installed (608.2):

An approved expansion tank shall be installed in the cold water distribution piping downstream of each such regulator to prevent excessive pressure from developing due to thermal expansion and to maintain the pressure setting of the regulator.

A water system provided with a check valve, backflow preventer, or other normally closed device that prevents dissipation of building pressure back into the water main shall be provided with an approved, listed, and adequately sized expansion tank or other approved device having a similar function to control thermal expansion.

A leak from your water heater’s pressure relief valve is a major concern, especially if it’s the first time dealing with this problem. While some people tend to panic and get help immediately, others may just shrug their shoulders and assume that the leak is a common occurrence. However, there are many causes of leaks in water pressure relief valves. And all these must be addressed immediately given the high risks of property damage and hazards that can occur if the issue is ignored.

The pressure relief valve gives steam and water a chance to escape when either the pressure or temperature in the water tank gets too high. A malfunctioning valve can cause the water heater to explode and is the major cause of water heater explosions. In water heater pressure relief valves, the valve is set to open when the pressure exceeds 150 psi.

A leaking valve is not always a broken valve. In some cases, a water heater’s pressure relief valve may leak because it is functioning as intended. As excess pressure is relieved out of your water heater system, some water may leak. This necessitates the need to test the pressure in your water heater.

The process is not complicated. However, if you are not comfortable checking the water pressure, you can always contact your technician. To test the pressure, use a pressure gauge and attach it to either the cold-water pipe or the hot water pipe. However, one of the easiest places to connect the pressure gauge is the outdoor hose faucets. For this, ensure you purchase a pressure gauge that is designed for garden hoses.

Turn off all water outlets and faucets. The pressure reading should be between 40 psi- 80 psi. If the gauge shows a psi reading of 150 and above, then the cause of the leak could be high pressure. If the water pressure is normal and the leak is persistent, then high water pressure is not the cause of the leak.

If you get a high-pressure reading, then you could be dealing with a closed plumbing system issue. This means that when the water is heated, the pressure increases as it should. But with nowhere to go, the valves open to relieve the pressure. Luckily, this can be solved by installing an expansion tank that gives the pressure an outlet other than a pressure relief valve.

Although rare, your water heater’s pressure relief valve could be leaking as a result of excessively high temperatures. However, the water has to be near the boiling point. To check the water temperature, ensure you turn on the hot water faucet. Run the water for one minute and use a meat thermometer to take the temperature reading. The temperature should be around 120 degrees. If more than this, then you need to have the water heater checked. The water temperature would need to be close to 212 degrees to set off the relief valve.

While this is an uncommon occurrence, it is not far-fetched. Your technician could have used a pressure valve for another appliance since they have the same function. However, these other pressure relief valves are set to go off at a lower psi. For instance, boiler pressure valves go off at 30 psi. If installed in a water heater, you are likely to get leaks immediately after installation. As such, if you have had your water heater for years and only experienced the leaks after a long period, then this is an unlikely cause of the leak.

A slight leak may occur if your water heater’s pressure relief valve has not been opened for a while, say a few years. While this leak is normal and may not be an indicator of a problem with the water heater system, you may need to replace the valve if the leak becomes more serious. It is cheaper to replace the entire valve than to repair it and have to deal with the same problem later on.

A leak in your water heater’s pressure relief valve could also be caused by a faulty pressure relief valve. While pressure relief valves barely break down, excessive wear and improper installation can cause extensive damage. Unfortunately, a faulty pressure valve can not be repaired and must be replaced. However, the cost of pressure valves is affordable and ranges around $30.

Know your water heater and how it functions– Water heaters can be intimidating, especially for people with less technical know-how.  Understand what every part of the system plays in heating water such as the water shutoff valve, drain valve, thermostat, and pressure relief valve. This eases the maintenance routine and ensures you have a fair understanding of any malfunctions.

Insulate the pipes and the water heater– By insulating both the cold water and hot water pipes, you get to prevent condensation while also reducing heat loss. Also, insulating the water heater helps to keep water hot when surrounded by cold air.

Carry out regular maintenance– Inspect your water heater monthly, ensuring that all valves and pipes are in good shape. This also helps you catch corrosion and leaks early enough before they turn out to be bigger problems. And every year, carry out a water heater flush. Given that you cannot pinpoint all problems, have a qualified technician inspect the system annually.

Regardless of the possible cause of a leak in your water heater’s pressure relief valve, please contact a qualified plumber as soon as possible. And if you think it’s a problem that you can solve without getting help, ensure you have a qualified plumber confirm that the system is performing optimally after. Water heater issues should not be taken lightly as they can cause more issues, even explosions.

If you’ve been having issues with your water heater recently, you might find that you’re paying high energy bills, not getting access to hot water when you want it, or your water pressure is low.

Fortunately, by understanding how relief valves work, you can solve whatever problem you’re having with the one on your water heater. In this article, we’ll review everything you should know about this valve.

A water heater pressure relief valve, also referred to as a T&P valve, pressure relief valve, or water heater temperature valve is a safety feature that you can find on any water heater. The reason it’s there is to keep you safe in case the water pressure is too high.

Without this safety feature, your water heater could end up breaking. You could potentially end up with burns if the high water pressure is dangerously high.

This valve also ensures that there aren’t any leaks in your water heater, which would lead to low water pressure when you want to use it to wash the dishes or take a shower.

The water heater pressure relief valve is in place so that it can relieve excess pressure and temperature in a water heater if either of these is too high. Because this everyday appliance is a closed system, thermal expansion occurs in water heaters.

Here’s how it works. Whether your water heater is heated by electric elements or a gas burner, both the metal tank and the water inside expand when the hot water temperature is somewhere between 120 and 140 degrees.

It’s totally normal for the water and water heater to expand to a certain extend. After all, this is what naturally happens when the temperature rises.

However, when the temperature is 210 degrees—or the pressure is 150 pounds per inch (psi)—this is far too much pressure and heat in the water heater. If it’s the case, you should change your hot water heater temperature.

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.

On the micro-level, the functioning of this valve works like this. The relief valve itself has been set up by a professional or pre-designed to open when the temperature or pressure reaches a dangerous level.

When functioning properly, it will open as it’s designed to when the levels of heat or pressure are high. The liquid comes out through this auxiliary route, relieving the heat and pressure within the water tank.

This specific state that the water heater is in is called the “blowdown.” Usually, the “blowdown” is defined by professionals (and is used in the design or set up of the valve) as a specific pressure percentage.

The “blowdown” is usually somewhere between 2 and 20%. Once the pressure has reached the “blowdown” amount, the pressure relief valve will close again so that you can use the water heater as intended.

If you’ve been noticing any issues with your water heater pressure relief valve, then you need to know where it is on your water heater. Usually, you can find it on the top or side of this appliance. It’s a valve that’s connected to a plastic or metal discharge tube that points up.

The water heater pressure is already installed when you receive your water heater (or buy a home that has one already). It’s actually welded onto the tank; you’ll see a threaded inlet where it is.

This is for safety reasons. Everything has been done according to standards that have been mandated by plumbing codes. So if you’re having any issues with the valve, you’ll have to call a professional to have it fixed.

This said, if you’re only having issues with the discharge tube, this is easy to replace. You won’t have to drain or power down your water heater, and you can deal with it yourself.

This said, considering that there might be other issues causing discharge tube problems—issues connected to high water pressure or temperature—it’s safest to have a professional deal with this too.

If you suspect there’s a problem with your water heater pressure relief valve, you can do a test. This is actually good idea if you don’t have any problems at all, as this type of maintenance will protect your water heater—and yourself.

To get started, identify where the relief valve shut off is. Usually, you can find it upon the cold water feed, which is on top of the water tank, on the right side where the inlet is.

Finally, release the level so that it quickly snaps into the original position. If it doesn’t snap quickly into this original position, then your water heater valve isn’t working and needs to be replaced.

When your water heater pressure relief valve isn’t functioning properly, it’s usually for one of to two reasons. It either sticks so that it doesn’t properly open or close, or it has a leak, which means that it’s continually dripping, lowering your water pressure.

If your valve is sticky, then it becomes stuck in a closed (downward) or open (extended position). If it’s closed, then the valve won’t be able to relieve the heat or pressure that builds up in the closed water heater system. There could be a rupture as a result.

Sometimes, you can easily fix this problem by opening and closing the valve lever a few times. However, if it continues to stick, then you’ll need to replace it.

Your water heater is leaking? Make sure that it doesn’t come from the valve before replacing it. If your pressure relief valve is leaking, then this maybe because it isn’t seated properly in the tank’s threaded opening. This is quite a common issue if you’ve recently replaced your old valve with a new one. To fix this issue with this cause, you have to take several steps.

If the lever snaps into its original position and it’s still leaking, you need to turn off the gas valve by turning it to the off position. Then, shut the water off so you can replace the valve safely.

If a water pressure issue is what is causing the water heater pressure relief valve to not work, then it might be dangerous for you to change the valve yourself. Generally speaking, it’s a good idea to hire a professional to protect yourself.

Now that we’ve reviewed everything you should know about a water heater pressure relief valve you might have realized that you need to replace your water heater valve. However, to be as safe as possible, you want to hire a professional.

The pressure relief valve on your water heater is an essential component to providing year-round comfort and keeping you and your family safe. Without this component, your water heater could overheat—causing it to break down. View our tips to become familiar about how this relief valve works and how to spot common issues.

You will find a water heater pressure relief valve on just about every standard hot water heater. Once the pressure and/or temperature inside your water heater gets too high, this component relieves the excess pressure. This decrease helps the temperature to return to a safe and stable level. The relief valve also prevents water leaks and keeps the water pressure from getting too low.

A valve is a one-way pipe that allows elements to pass through it. Here’s how a water pressure relief valve works: when the internal temperature of your water heater increases to a certain point, the appliance will naturally expand.

This expansion, however, should be limited. When the temperature gets too high, the relief valve opens to expel excess hot water and steam from the water heater so it doesn’t overheat.

You should always know where to find the pressure relief valve on your water heater in the case of an emergency. This device is typically located on the top or side of the appliance and is attached to an upward-pointing discharge tube.

If your water heater’s pressure relief valve has gone bad, you’ll probably know it. Here are the five most common signs that you need to repair or replace this device.

The most obvious and dangerous sign that your water heater pressure relief valve has gone bad is if it causes flooding in your home. If you experience this problem, cut off the water supply and have a professional come out to fix it.

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.

As the water heater pressure relief valve ages, it can start to corrode and make the water in your unit dirty. If this becomes a consistent problem, have a technician take a look at the valve. You’ll likely need to clean, repair, or replace it.

Since the pressure relief valve removes excess hot water from your unit, it will naturally leak some water from time to time. But if it leaks excessively and often, you’ll need to take a look at the valve.

While it’s normal for some water to leak from the pressure relief valve, the unit itself should never leak water. This can happen when the valve doesn’t properly relieve pressure from the unit and, in response, the tank ruptures.

If you’re looking for safe, reliable, and high-quality water heater repair and water heater installation services in the Northern Virginia area, call our team of technicians by phone at (703) 543-9649. With 50 years of experience in the HVAC and plumbing industries, we have become the trusted choice for achieving premium home comfort. In addition, our team of licensed plumbers offer other types of plumbing services such as sink installation, sump pump repair, gas line installation, and sewer line replacement. Our team of technicians won’t let you down. Schedule an appointment with one of our technicians today.

A leaky water heater is nothing to take lightly. Over time, the leaks could cause water damage to the flooring and any surrounding items in your utility area, and they’ll only get worse over time. If your water heater is leaking from the bottom, this almost always indicates a serious problem with your unit.

Wondering why your hot water tank is leaking, and if you should call a professional like G&C Plumbing and Heating to troubleshoot and repair your unit? Read on, and learn about the most common causes of hot water heaters leaking from the bottom.

The T&P (Temperature & Pressure) relief valve is a safety feature found on all commonly-sold hot water heaters. It releases excess pressure from the tank through a tube directed at the floor – if the pressure gets too high in the tank, water will typically be sprayed through this tube as the pressure is relieved.

If you check your discharge tube and it’s wet, the T&P valve is probably the culprit. It may be faulty, and activating even when the pressure inside the hot water tank is normal. You’ll need to call a plumber to replace the valve and ensure your tank stops leaking.

In rare cases, though, your T&P valve may be functioning properly – and there may be too much pressure in your hot water tank. Pressure may build if the hot water tank is heating water too high (exceeding 140-145° F), which could happen with a faulty temperature regulator. Your hot water heater may be at risk of bursting if it exceeds its rated PSI, so contact a plumber for help immediately.

Another common cause of water heaters leaking from the bottom is a drain valve that’s not completely closed or is faulty and is leaking. The drain valve is used to drain out the tank to perform maintenance or repairs on the water heater, and is also used to drain sediment that gathers at the bottom of the tank.

If your drain valve is leaking, it may not be damaged. It’s possible that it’s just not completely closed. You may have knocked the handle loose at some point, loosening the drain valve slightly and allowing some water to drip out. Check the knob or handle and ensure it’s completely tightened.

If the water stops dripping, congratulations! Your water heater is in good shape. But if the leak continues, the valve itself is faulty and will need to be replaced either by you (if you’re handy) or by a plumber. The leak will only get worse with time, so we recommend handling the issue as soon as you can.

The final – and most common – reason that your hot water heater may be leaking from the bottom is due to damage to the tank itself. If your hot water tank is leaking, that means it’s suffering from an internal, structural problem that is allowing water to leak out and pool at the base of the tank.

The most typical cause of a faulty tank and internal tank leak is a failure to remove sediment from the hot water tank. This is particularly common in areas with very hard water. You should flush your tank and remove sediment every six months.

If you don’t, the efficiency of your water heater will begin to suffer. And over time, the sediment can contribute to corrosion and cracking of the tank shell, leading to a leak that will allow water to pool around the base of the unit.

In the case of internal damage to the hot water heater, you’ll almost always need to replace the unit completely. If you think that your hot water tank is compromised but you’re not certain, it’s a good idea to hire a plumber to take a look at it – that way, if the issue isn’t with the heater tank, you can avoid the expense of purchasing a brand-new unit.

A leaky water heater is a big deal. If your water heater is leaking, it’s likely in need of urgent repairs. Read about if your water heater is leaking around the top.

Contact the pros at G&C Plumbing and Heating. We can examine your hot water heater, determine the root cause of the problem, and recommend the appropriate maintenance and repairs – or install a new water heater to replace your damaged unit. Contact us now to get the help you need.

Now we are really getting down to business. Once your water and power source are turned off, it"s time to find the source of the leak so you can correctly troubleshoot and repair it. Try identifying where the water builds up and clean it up. Then, the next day, if you notice an accumulation of water in the same place, you now know where to start troubleshooting your hot water heater leaking.

Do you notice a water leak at the top of your water heater? Inspect the two pipes located on the top of your water heater. They are called the cold water inlet pipe and warm water outlet pipe. These pipes bring water into the tank to be heated and then out into your home for use. If their fittings or connections are loose, this could be the source of your leak. In this case, you can tighten the pipes with a pipe wrench.

If you see water seeping down the side, it may be your Temperature and Pressure Relief Valve, also known as the T&P valve. Every water heater has a T&P valve. This is a safety feature that is meant to release water if too much water pressure builds up. If you see water leaking from the T&P valve, first make sure the temperature is not set too high. If the temperature is too high, it may cause excessive pressure and trigger this safety mechanism. According to the Department of Energy, the temperature of your tank-based water heater should be 120 degrees Fahrenheit. However, if the temperature has not been set too high and leakage persists, you may have a faulty valve. If so, you need to consult an expert to replace it.

At the bottom of the water heater, you can find a drain valve. The purpose of this valve is to drain the water heater for maintenance. If you see water leaking from the bottom of your water heater, check that the drain valve is completely closed. If it is still leaking, it may be loose. By using a pipe wrench, you can try tightening the drain valve slightly. It is important to not over tighten the valve, as this would cause it to leak more. You may need to replace your drain valve if it continues to drip after you troubleshoot it.

If you have an unexplained pooling of water near the base of your water heater tank, it may be the result of a crack in your hot water tank. Unfortunately, a hot water heater repair will not be enough; you will need a new water heater replacement.

If there’s a leak at your temperature and pressure relief valve, first test to ensure it’s operating correctly. If it isn’t working properly, replace it.

If the T&P valve is operational, check to see if you have a pressure-reducing valve, usually near the main water shutoff. If a pressure-reducing valve or other form of check valve is present, you’ll need to add a potable expansion tank.

This article describes the causes of leaks, drips, or discharges from pressure relief valves, temperature/pressure relief valves, or TP valves found on heating boilers, water heaters, or the simpler pressure relief valves found on water pressure tanks.

We list the wide variety of possible TP Valve leaks and how to find and fix each of those problems, including how to fix a leaky pressure relief valve or leaky TP valve on a boiler, water heater, or water tank - what are the possible causes of leaks at these safety devices. Safety Hazard Warnings About Dripping or Leaking Pressure Relief Valves.

How to use an expansion tank to relieve high water pressure. T&P Valves Installed on Gas Sidearm Heaters: special problems. Closed Hot Water System & Thermal Expansion Problems.

So if you see water actually spilling or even if it"s just dripping at the temperature/pressure relief valve on your heating boiler or water heater, the cause needs to be found and fixed promptly, and it may be appropriate to install a new T&P valve (also called TPR valve) after those repairs are complete.

Gas sidearm heater TP valves: The T&P valve is installed on a sidearm gas heater that is causing an overheat condition at the sensor point of the valve (This thermal expansion is discussed

Expansion tank defects or problems: if the expansion tank or compression tank on a hydronic heating system boiler or on other thermal expansion systems is itself defective (waterlogged, leaky, damaged internal bladder) system pressures will be excessive due to otherwise normal pressure & temperature variations during system operation, resulting in spillage at the relief valve.

Leaks into the heating boiler or water heater: leaks into a heating of water from a higher pressure building source can cause recurrent TP valve leaking. For example, if the tankless coil in a heating boiler is leaky, higher pressure water inside the tankless coil may leak out of the coil into the heating boiler.

Similarly, an internal leak in the heat exchanger coil of an indirect water heater can send water from the water heater"s potable water into the coil and thence into the heating boiler.

This same leak problem can cause high water pressure in a heating boiler that is used to heat water in an indirect-fired water heater. In that case, a coil containing boiler water (typically at 12-29 psi) that develops a leak may accept higher building pressure water from the building water supply to the indirect water eater tank (or cylinder) that is typically between 20 psi and 70 psi.

Diagnose this problem by observing that when the boiler is left OFF and its own water feeder is left OFF but building water supply is left ON into the tankless coil on the boiler or ON into the indirect water heater, boiler pressure will creep up several hours. With a reader we discuss this possible TP valve leak cause in the FAQs section of this article.

Watch out: under normal conditions, because building water supply pressures are above boiler pressures, an internal leak in the tankless coil or indirect water heater"s heat exchanger coil will cause boiler pressures to rise. But there can be exceptions in the direction of water leakage, as we explain

A deteriorated gasket inside the relief valve or corrosion on the valve seat can cause leaking at the valve; we find this mess occurring when someone lifts the "test lever" on a older P/T valve that has not been tested or operated for some time. A brittle piece of gasket can be spit out of the valve and it will then keep leaking.

The wrong T&P valve has been installed or set to too-low a working pressure. (Proper set pressure is at least 20-30 psi above the working pressure of the equipment to be protected).

Thermal expansion problems: A closed water system with thermal expansion and no means of relief can cause leaks at the pressure/temperature relief valve, such as

Can occur on a hot water heater (hot water cylinder, calorifier, hot water tank) with some building piping arrangements, particularly where a check valve or pressure reducing valve are used.

See THERMAL EXPANSION TPR VALVE LEAKS for an explanation of why thermal expansion leaks occur at the relief valve on hot water systems & what to do about it

Can occur also a hot water heating boiler (used for building heating) at which the boiler"s thermal expansion tank has become waterlogged or has a ruptured internal bladder.

Water expansion pressure (thermal expansion) increases in any closed plumbing system, particularly where a check valve installed close to the water heater.

Watts suggests installing a bypass model water pressure regulator that lets the excessive pressure head back to the street main or building water supply system - a solution that only works if the supply pressure is lower than the T&P relief valve spill pressure - which it usually is.

Water hammer: The building plumbing system suffers from water hammer. Water hammer in buildings causes surging in the water piping that in turn can cause leaks at pressure/temperature or other pressure relief valves, particularly at the pressure safety valve found at water pressure tanks.

Water heater temperature too high: The water heater temperatures are excessive. For example on an electric water heater a malfunctioning control can overheat the water e.g. the water heater thermostat is not working properly and is not shutting off the heat source when it should -

Water pressure too high: The building water supply pressure is too high or periodically water pressure fluctuates and is too high at times. Pressures over 70 psi in a typical building tend to cause leaks at plumbing fixtures and higher pressures are likely to cause or contribute to leaks at TPR valves.

Water pressure reducing valve / water feed valve problems: On a hot water hydronic heating system, if the water pressure reducer/feeder valve is not working properly it may over-feed water into the heating system causing overpressure.

Combinations of factors causing TP Valve Leaks: OK so this is more than 12 causes of TPR valve leaks, but keep in mind that the temperature/pressure relief valve leak causes listed above can also occur in combination. For example high incoming water pressure alone may not cause a TPR valve to leak but if we add water hammer then the valve may be leaky.

As our photo shows (above left), mineral salts left behind as hot water evaporates from the mouth of a pressure or temperature relief valve can completely clog the spring that is intended to allow the relief valve to open under excess (unsafe) pressure.

The impaction of the relief valve spring with copper and calcium salts in this photo means that the valve is almost certainly not going to open should the heater"s internal pressure become unsafe.

The drip shown at the mouth of this relief valve demonstrates that a relief valve can drip and leak for a long time without anyone observing this dangerous condition.

Technical note: why must the TP Valve point "down"? Take a look at the photo above. If a relief valve is dripping the deposit of minerals inside the valve will accumulate still more rapidly if the valve points to the side or upwards. The result is a clogged valve as we explain above - a dangerous situation that risks an explosion.

Watch out, serious safety hazards can be caused by dripping at the TP discharge line: often the dripping is caused by thermal expansion of hot water.

For details please see THERMAL EXPANSION TPR VALVE LEAKS - an explanation of why thermal expansion leaks occur on hot water systems & what to do about it

Also see HOT WATER PRESSURE EXPANSION RATE - for an explanation of just how much pressure increase to expect when heating water. In explaining why the relief valve on a water heater may be dripping

With a sidearm gas heater a common problem is frequent T&P valve opening even though there is very little hot water in the hot water storage tank. That"s because an overheated condition exists right at the sensor point of the T&P valve - most of the overheated water is "congested" at the top of the tank.

This problem can be caused by undersized circulation piping between the sidearm heater and the water tank. Undersized piping between the sidearm heater and the tank (supply or return) amounts to a restriction of the circulation area (or volume).

When this "too small" circulation area or volume is combined with a heater whose BTU input rate is higher than that undersized volume can carry, proper circulating does not occur through the tank nor through the sidearm heater coils themselves - the "congestion" referred to above occurs.

In turn this congestion (think of it as a hot water traffic jam) causes overheating right where the T&P valve sensor is located, thus causing the valve to spill hot water repeatedly.

Because there is just a small volume of "too hot" water where the valve is located, the valve opens, spills the small amount of hot water, then is cooled and closes after just a short interval.

[The system we used for years used 1 1/4" diameter copper piping - Ed.] Non-ferrous piping is preferred to reduce the chances of clogging from rust debris - a clue that warns us that even 3/4" piped gas sidearm heaters can clog from rust or scale formation and will then exhibit this problem if the piping is iron.

With an automatic gas storage heater installation, either the heater thermostat is acting abnormally (not shutting off when it should) or stacking temperature conditions are causing this TP leak. - paraphrased & adapted from information from the Watts Regulator Company. [10]

RELIEF VALVE LEAKS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

[1] "Residential Electric Water Heater Installation Instructions and Use & Care Guide", American Water Heater Co., October 2001, American Water Heater Co., Johnson City, TN, [manufacturer of residential & commercial water heaters, also manufacturer of Polaris/Commercial water heaters], Tel: 800-999-9515, web search 1/12/2012, original source: americanwaterheater.com/support/manuals/res-elect.pdf [copy on file] [Technical review requested 1/25/2011]

[3] Pounds of lime deposited vs. temperature and hot water usage: see Purdue Bulletin #74 (also provided by A.O. Smith in the article below). Purdue"s chart shows the number of pounds of lime deposited per year as a function of the water usage in gallons per day, with an assumed 10 grains of water hardness.

[4] "When, Why, and How to Remove Water Scale from Tank Type Glass-Lined Water Heaters (for non glass-lined tanks, consult water heater manufacturer)" PDF provided by A.O. Smith Water Products Company - hotwater.com/lit/training/4800r9.pdf 800-433-2545 - 01/07/2009.

[6] A.O. Smith"s Form No. 4778* All about Deliming Coil-Type/Tube-Type Commercial Water Heaters and Hydronic Boilers *Normally supplied when ordering Part No. 4930 Motorized Deliming Pump Kit

[7] "Building Owner Water Heater Safety Notice", Building Department, City of Colleyville TX, web search 09/24/2010, original source: http://www.colleyville.com/dmdocuments/Building%20

Water heater safety is imperative to the occupants of a building or structure. If improperly installed, water heaters can be detrimental to the structure, as well as being potentially fatal to its occupants. The proper installation of a water heater is so important that according to Texas State Law all water heater installations must be inspected by a state licensed plumbing inspector.

[8] Rheem Electric Water Heater "Owners Guide and Installation Instructions", (Australian models) rheem.com.au/images/pdf/owners_dom-elec_121996C_0707.pdf

[9] Watts, 815 Chestnut Street, North Andover, MA, USA 01845-6098, web search 09/18/2010 original source: http://www.watts.com/pages/learnAbout/reducingValves.asp?catId=64

[11] "Four hurt as water heater explodes", Elaine Porterfield, Paul Shukovsky, Lewis Kamb, Seattle Post Intelligencer, 28 July 2001, web search 25 Sept 2010, original source: http://www.seattlepi.com/local/33094_boom28.shtml

In small scale testing, the Mythbusters started with a small six gallon water heater and disabled all of its safety features under the theory of poor installation or neglect. While the water heater eventually ruptured, it did not explode like a rocket. The Mythbusters then upgraded to larger thirty gallon water heater which exploded with significantly greater force, sending the water heater several hundred feet into the air. In order to confirm the stated myth, the Mythbusters obtained a full size fifty two gallon water heater and built a shack around it with a roof that followed standard California building codes. The water heater eventually exploded, shooting through the roof five hundred feet into the air and disintegrating the shack. In light of these results, and the fact that there is documented evidence corroborating the myth, the Mythbusters deemed it confirmed.

Because of built in safety devices most water heaters safely operate day in, day out without any major problems. But don"t let the excellent safety record of water heaters lull you into forgetting about the explosive potential of these marvels of convenience. When a water heater explodes, it releases a tremendous blast force which can easily demolish a building.

Randall Hilton and crew, with help from the Service Roundtable has prepared this video of a water heater explosion as a demonstration of the explosive power of a simple water heater. The hot water tank explodes using the steam pressure that any water heater can generate when the thermostat and temperature pressure relief valve (T&P valve or PT valve) malfunction. We were impressed by how far the tank flew after the water heater exploded. Click on the links below to view the video. Then, visit the Q&A page for warning signs as well as simple steps which can help you prevent your own water heater from exploding.

TECHNICAL REFERENCE GUIDE to manufacturer"s model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop Weldon & Associates

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I have did everythings you said but my valve still run water when I cut it back on. Even if the valve is cold it still run and have a lot of pressure. What should I do.

Maybe from now recommend turning the main supply line off. Today we changed a relief valve on a heater in an attic. The plumbing had been crossed. The shutoff was on the cold inlet side of the heater but the cold water was coming in to the hot side. Dip tube changed and c and h crossed. Not good is a understatement. Just an idea but thats how I will approach it from now on. Turn off main. Real fun going behind a sorry plumber

I had a leak from pressure valve which finally just blew across room. I replaced valve but when I turned the main water valve back on only upstairs water runs. I didnt turn anything else off but the gas and delmarva told me how to do that. for three days I have no water on 1st floor, but have water in basement and second floor. Help!

I have attempted to change the TPR valve b/c it has a slow leak, I have followed all the steps, however I am unable to remove(unscrew) the TPR valve. I had a 250lb man use his weight and a pipe wrench to try and remove the valve in order to replace it with a new one. A cheater won’t work b/c that 250lb man bent the relief valve drain pipe threads. Can I try to use WD-40 or some other trick of the trade to get the TPR valve off w/o damaging anything?

I replaced my old hot water tank about 2 years ago because no one I called could not get the overflow pipe to stop leaking, even after replacing the valve twice! Within 2 weeks of installing the new one…it started leaking too. As I forestated, that was 2 years ago…and it is still leaking. I am really frustrated about how to stop this leaking. The valve has been replaced on this once, and as of today, a plumber, who is a friend of ours lowered the pressure…?? and within an hour after he left, the leaking started again! What else can I do?? Thank you.

Am going to replace the valve, there are two to choose from, both have the same pressure specs, but one has a longer plastic rod or shaft protruding out the back of the valve, apparently into the tank. What does this rod do and what difference would it make between the longer and shorter versions (besides about $4.00) ?

Bought a brand new n gas heater. When all installed noticed water leaking from outside overflow pipe. Replaced pressure valve but cannot screw new pipe all the way. Threads are not grasping all the way. Have changed PV twice. PV seems to not fit properly are PV universal?

Hi I have a problem with pressure relieve valve for water heating system , the valve next and connected to tank above the furness ,leeks only when heating system is working , is that because of a lodging …? in the tank above the furness.

When water is coming out of the pressure relief valve on your water heater, it could signal that too much pressure is building up inside the water heater (which is what the valve is designed for) due to the burner or element not cutting off, in which case the water heater needs to be repaired or replaced. Or it could be a sign that the pressure relief valve itself is not closing properly, in which case all you need to do is replace the pressure relief valve on the water heater.

Out of dire necessity, I bought a new Hot Water Tank three weeks ago, the drip tube has leaked since installation. Replaced pressure relief valve twice with no change. Replaced Hot Water Tank (what a chore!) and the relief valve still leaks. We are on public water and never had any issue with pressure. I had a plumber do the last replacement of the valve and he says its impossible to keep leaking. And burner is working fine. But, it does leak! What can I do?? Is there a “wrong” way to install a drip tube? Should I try another tank?

That depends on whether the pressure relief valve is leaking around the threads where it attaches to the hot water tank or if it is leaking out of the inside of the valve itself. In either case, start by replacing the pressure relief valve, using a different brand in case the valve itself is defective. Make sure the threads on the valve seal to the tank without leaking using plumber’s thread compound. If the valve is leaking around the threads into the tank, the threads on the tank might be the problem. Good luck with your project!

Hello. I have a new hot water heater AND expansion tank (both less than two years old). There has always been water leaking from out of the side discharge tube but less than a gallon per week. Four months ago I had to replace the pressure guage, expansion tank, and both pressure values in my furnace. The hot water tank continued to leak at a slow rate. It was easy to keep up with. Today the water is pouring out of the discharge tube. About a gallon per hour. I turned off the heater and flipped the valve to release about four gallons of water. The leaking has stopped but I haven’t turned the hot water heater back on. I researched on line and discovered the main water line pressure may be too high. I can live with a slow leak but how do I fix the current problem? Do I need to completely drain the hot water heater? Thank you.

We noticed some time ago the hot water system overflow pipe was leaking water. It is under the house. I put a hose on the end of it to catch the water as I live in the country and am on water tanks water is vital. to my horror it driping at a fast rate. Loosing about a bucket in an hour or two. I also noticed the pressure relief value is hissing and a very small amount of water is coming from it. I have now turned off the (I think) input value but water is still coming out of the overflow pipe. I would pressume once the level of water in the tank goes down it will stop leaking. this tank is 18 years but most of its life it was turned off as its installed in a weekender. We now live in permanently. Are we wasting time getting a plumber or should we buy a new one???

It’s hard to say without actually examining your hot water tank whether the problem lies with the tank itself or the pressure relief valve. If the hot water worked okay and wasn’t excessively hot or steam didn’t come out when you turned on a faucet, the problem is probably with your pressure relief valve. Replacing the valve is a simple job for a plumber and doable for a DIYer that has some experience with plumbing. If you have turned off the cold water valve going into the tank, water should not continue to come out when you open a hot water faucet other than possibly a small drip.

Pressure relief valves have tapered pipe threads which require either Teflon tape or pipe joint compound (pipe dope) to seal properly. When using Teflon tape, be sure to use the recommended type for your application, and wrap it around the pressure relief valve in a clockwise direction (when looking at the inner end of the valve). If removing the valve and resealing it doesn’t stop the leak, there may be damage to the threads on either the valve or tank. Try replacing the relief valve to see if that stops it. If the valve still leaks, the threads in the hot water heater are probably damaged. I don’t know an easy fix for that, but you may want to have a plumber look at it to see if it can be fixed. Good luck with your project!

i turned off the water to water heater,opened the relief vavle on the side or the water heater. then i drained the water heater, now it leaks outside from the brass overflow,i need help its only two years old. can someone give me a tip on how to stop this type of leak?

The relief valve on my water heater is dripping, but stops when I shut off the main water line. It drips agian once the water line is turned on. The hot water that comes out of all the faucets in the house also seem hotter than normal. Could this be why the valve is leaking?

It’s possible that the water pressure in your house is too high due to a faulty thermostat on your water heater that’s causing it to superheat the water (try turning down the water heater to see if it lowers the hot water temperature), but the problem is probably a bad seal in the pressure relief valve. If so, the valve will probably need to be replaced. Good luck with your project!

My hot water heater is leaking from the overflow valve located on the side of my gas heater, my tub is half full but the water is cold, it probably has been weeping for months. My water seems to be very hot but my showers do not last long with hot water. Last night I actually had steam visible coming out of my faucets. The heater was manufactured in 2002, it is a State Select Product. The heater kicks on mainly once Hot water is used and the flame seems to be working fine in this reguard. Is this a hjeater going bad or is there a fix for the issues mentioned.

If you have steam coming out of the faucet, it sounds like the thermostat on the heater is not working right and allowing the water to get too hot, which could cause the pressure to build up in the lines to a dangerous level and may even rupture the pipes or cause the glue in plastic pipes to come loose. Since the hot water runs out quick, my guess is that your tank is also full of sediment. You could try draining the tank to remove the sediment and replacing the pressure relief valve, but it sounds like you’re due for a new water heater to me. Good luck with your project!

Thanks Ben Erickson, I actually went ahead and replaced the Pressure relief valve. Bad news, The valve is leaking again within the first use of the hot water. I did drain the tank and it yielded White particles, almost looked like chlorine or even pvc like cuttings. I will try the Thermostat next. I do have a expansion tank in the crawl space pretty far away from the heater, could the tank be bad thus forcing the Pressure valve to weep?

The only reasons I know of that would cause the pressure relief valve to leak are if the valve itself is defective (such as the gasket seal being bad) or if the pressure in your system is too high. You might want to have the utilitiy company or a home inspection service check your water pressure (both hot at the tank and cold at a faucet outside).

Thanks again Ben, the leaking has no signs at the threaded connection it is coming only out of the overflow stem pipe. no hint at the face of the tank. When I purchased the valve the service agent mentioned the cold water expansion tank could be bad. So you do not think the temp control mechanism is the problem here?

Ben, I should note, the valve starts leaking in the mid to end portion during the re-heating process. The cold water in-bound pipe gets very hot, once the water is used in the house the pipe then becomes very cold. Then after the flame process stops the drip from the overflow stops, this is not a consistent drip it only occurs during the heating up cycle.

Ben, I replaced both the water heater and the cold water Expansion tank, the exp-tank was shot, the heater was full of sedimant and leaking inside the unti as well. Thank You for responding to my problems, I will be back with future dilemmas, this is a great link, Enjoy The Presidents Day Holiday.

I have pooling from the inlet fittings on top of my (gas) hot water tank. I tried to tighten the fittings and they still leak. Do I need to replace the fittings.

We have a water leak. The plumber has narrowed it down to the hot water heater. With all water valves shut off (toilets, sinks, ice maker, washer and hot water heater), the meter stops running. When the cold water valve for the hot water heater is turned back on by itself, the meter runs. No visible water in or around the water heater. Currently using around 1 gallon of water per hour.

Turning off the cold intake valve to the water heater not only turns off the water to the hot water heater, but also to all the hot water pipes in the house. If the water heater itself isn’t leaking, the leak must be either in the hot water pipes or the hot water side of a faucet. If the pipes run in an attic, basement, or crawlspace, follow each of the hot water pipes and look for leaks. If they’re buried under the house, look for damp or wet soil in the crawlspace, if they’re embedded in a concrete slab, it will be hard to find the leak and impossible to fix it if you do without rerouting the pipe. Good luck with your project!

i was told there too mush pressure in the tank i told them there not hot water yet and still leaks out of the values i guess 2 things but not sure please help…will draining a tank reduce pressure an why is there pressure come from if no hot water yet…..and will a baldder tank help….thanks garth

we have replaced the pressure valve on our water heater 4 times now and as soon as we do it keeps hissing and releasing water. We have an expansion tank and back flow preventer. We have been in this house for 5 years and this problem just started a year ago. The water heater was manufactured in 2004 – does this mean we should get a new water heater? Uggghhh!

The pressure valve on our water heater is flowing freely. Our house used to be on well water and on the cold water inlet line to the water heater there is a reverse-flow valve, but we are now on rural water. I suspect that this valve is causing, or increasing the leak from the water heater, is this possible? Do I need a reverse-flow valve or can I remove it? Would it be better to add an expansion tank?

Our hot water heater started leaking from the temp/pressure release valve pipe. A slow steady leak. We lowered the hot water temperature setting significantly and after about 1-1.5 hrs it stopped leaking. We slowly increased temperature over 2 days to see if it would leak again and then it did once we got close to previous temp. Since then (2-3 weeks)we have had it lowered to a lukewarm temp. and no further leaks. Is this likely a problem with the valve? the thermostat? the hot water heater is 10 years old.

If the water coming out of the tank isn’t excessively hot and the water pressure in your house isn’t overly high, the problem is probably a defective pressure relief valve. Depending on the type and model of pressure relief valve, they are generally set to open at pressures over 125 to 150 p.s.i., or temperatures over 210 degrees F, pretty extreme conditions. Since a pressure relief isn’t very expensive (usually under $15) I would start by replacing it to see if that solves your problem. Good luck with your project!

I have Bradford White gas water heater. The relief valve is on the side. I removed the plastic cover around it and leak is right from under the valve where insulation of the heater is. I can clearly see relief valve connecton to the heater and it’s not leaking. Does that mean I have tank corrosion on the side or there are some other pipes installed under the cover that might leak ?

have Bradford White gas water heater. It is leaking right at the connection into the water tank? Possible corrosion. Will we need to replace the T&P valve also or just remove and seal the connection better??

I have a slow leak from my relief valve…about 1 cup worth in a weeks time. i have replaced the valve twice and continue to get the slow leak. i have no other issues with the water heater pressure or heat wise…the water heater is about ten years old. is it time to call a plumber?

If the leak is coming from inside the pressure relief valve, replacing it with one rated for the PSI of the water pressure in your house should fix it. If the leak is coming from the threads around the pressure relief valve, then you need to use the proper thread sealant or tape when installing the valve. If the threads around the valve are still leaking after sealing them, there may be a problem with the threads on the relief valve opening in the water heater, and you would probably need a plumber to fix it. Good luck with your project!

hi, i have a hot water that is leaking from the drain in the side of the hot water heater, how do i get it to stop.If you can tell me step by step what to do. It has been leaking for about a week. It is hot water coming out of the drain.

I have electric hot water heater and cut it down very low and in the vacation mode since I was going to be gone about 2 weeks. I came home and cut it to about 125 or 130 probably and now it is hissing and just a couple drops of water I could feel around the pressure valve. Should I panic and call a plumber right away or did it do this because it had been set so low for 2 weeks? I cut it down to about 100 when the hissing started.

Over the past month, my water heater has been leaking through the relief valve, but it is not a steady drip. It only seems to happen late at night (midnight – 7am), and is not a constant release, but more bu