New hot water heater pressure relief valve keeps opening

Although a water heater has a lot more reasons to leak if it's been neglected for several years and had time to rust through, a newer water heater can leak as well. If you've just had a water heater installed and it seems to be leaking, don't panic. Most of the reasons a new heater will leak aren't catastrophic.

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Further Information:
Why would the pressure relief valve open?
What causes too much pressure in water heater?
How do I stop water coming out of my pressure relief valve?

Here are four possible explanations.

1. Poor Connections

If your water heater was installed in a hurry or has a loose or otherwise faulty fitting, a poor connection could be to blame for your leak. In addition, plumbing materials can experience damage from issues such as expansion and contraction caused by temperature changes, wear and tear caused by pressure, and more.

The connections, joints, gaskets, and other components that hold your plumbing system together can experience problems from these and other issues, and that includes the connections where pipes meet your water heater. If this is the case, adjusting the connections should stop the leaks.

2. Faulty Relief Valve

Water heater tanks have temperature and pressure relief valves that help them release any excess pressure caused by the hot water in the tank. However, if a valve is faulty for whatever reason, it may simply keep leaking even when it doesn't need to relieve any pressure.

In this scenario, your valve may simply need to be replaced. Your plumber can come out to diagnose any issues with the valve.

3. Non-Faulty Relief Valve

A leaking temperature pressure relief valve isn't necessarily faulty. These valves are designed to open up if the temperature inside the tank is too hot or the pressure goes over 150 PSI. So it could just be leaking because of too much pressure in the tank.

If your plumber tests the pressure and finds that it has gone too high, you may need both a new relief valve and an additional modification (such as an expansion tank) to prevent future pressure problems.

4. Leaky Spigot

The drain valve spigot at the bottom of your water heater tank is designed to allow flushing out of the tank every year or so. But in some cases, whether because the spigot is faulty or because something gets jammed inside, this spot may begin to leak. Typically this isn't a catastrophic issue for a water heater.

Your plumber can come out and check whether flushing the spigot out to release any debris fixes the issue. If not, he or she will proceed to the next troubleshooting steps and may either repair the valve or replace it completely.

5. Early Failure

This is unlikely, but you should keep in mind that your water heater tank could simply fail earlier than expected for some reason. A faulty product caused by a manufacturing defect, for example, or some other issue could mean that the wall of your tank has simply sprung a leak. In this case, the whole heater will need to be replaced.

The good news is that if you just recently had it installed, a failed tank should still be under warranty, which means you may not be on the hook to pay for a replacement. Of course, this assumes that you've kept the warranty valid (through proper installation and maintenance and so on).

These are just some of the potential causes of a leak if your water heater is still nearly new.

Remember, just because the leak may be an easy fix doesn't mean you should ignore it. Call us at AERO Plumbing if you notice that your water heater has started to leak. We offer emergency service so we can help you with your leaking heater no matter what time of the day or week it happens.

The pressure relief valve on a hot water heater can leak over time.

I just flushed my hot water heater as you mentioned and now the pressure relief valve is leaking. Is this something I can replace on my own, or should I call a plumber? —Leighton

Hi Leighton,

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. Whether you can replace it yourself will depend on your skill level, but as far as plumbing repairs go, it’s not that difficult. If you do try to fix it, here are the basic steps involved:

First, turn off the gas to the water heater, or flip the breaker if it’s electric.
Close the cold water cut-off valve going into the water heater.
Open the valve at the bottom and the pressure relief valve for a minute to drain a little water out of the tank and relieve the pressure.
Remove the overflow pipe from the pressure relief valve. If it’s been glued or soldered in place, it may have to be cut off.
Use a pipe wrench to unscrew the old pressure relief valve.
Wrap Teflon tape around the threads of the new valve, and screw it in until tight, orienting the overflow pipe opening away from the tank.
Reattach the relief valve drain pipe using Teflon tape on the threads. If you have to replace the drain pipe, use pipe (and glue) that is rated for hot water (such as CPVC rather than PVC).
Open the cold water cut-off and check for leaks around the relief valve.

Good luck with your project,

Further Information:

Water Heater Maintenance (video)
Closing Pressure Relief Valve When Draining Hot Water Tank (article)

Why would the pressure relief valve open?

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.

What causes too much pressure in water heater?

Why is My Water Heater Building Up Too Much Pressure? If your water heater is building up too much pressure there's likely three reasons. Either the temperature is set too high, there's a malfunction, or the water heater doesn't have an expansion tank.