Hot Water Tank Pressure Relief Valve Leaking - Causes and Repairs

If you have a hot water tank in your home, one important component is the pressure relief valve. This small valve plays a critical safety role in regulating excess pressure and temperature in the tank to prevent explosion hazards. However, relief valves can fail over time and begin leaking water, causing a range of problems.

We'll start by explaining what the valve does, then outline common signs of leaks, main causes, associated dangers, troubleshooting tips, repair or replacement solutions, steps for prevention, and when it's time to call in a professional.

Main Causes of a Leaking Relief Valve

There are several common triggers that can cause a relief valve to start dripping or leaking water:

Excessive Water Pressure

Consistent water pressure above 80 PSI can overcome the relief valve's pressure setting and cause it to leak. Periods of high pressure force the valve open when it shouldn't, allowing water to escape.

Mineral Buildup

Over time, mineral deposits from hard water can collect inside the valve, preventing it from sealing properly closed. This mineral buildup is a prime cause of drips and leaks.

Failed or Faulty Valve

Like any other mechanical component, relief valves can simply wear out or fail. A broken internal spring, worn out rubber gasket, or separated diaphragm will cause loss of seal integrity and leaking.

Thermal Expansion

As water is heated, it naturally expands in volume. With no place to go this added pressure can leak out of the relief valve. Lack of a thermal expansion tank exacerbates this issue.

Dangers and Problems of a Leaking Valve

It's important not to ignore a leaking or dripping hot water tank relief valve. Some serious consequences can unfold if left unaddressed:

• Water damage to floors, walls, and other home infrastructure
• Reduced efficiency and loss of hot water capacity
• Increased risk of mold growth
• Mineral stain damage on surfaces
• Higher energy bills from heat loss

Troubleshooting the Leak

Before attempting any repairs, start by troubleshooting the root cause of the leak:

Locate Exact Source

Verify that water is in fact coming from the relief valve and not another component like an inlet pipe fitting.

Inspect Valve & Pipes

Look for mineral buildup or corrosion, and check the valve's gaskets for wear and tear.

Check Water Pressure & Thermal Expansion

Use a pressure gauge on your main home supply line. Anything over 80 PSI could cause issues. Also check if you lack a thermal expansion tank.

Test Valve

Manually activate the pressure relief lever and check that the valve opens then reseats properly without leaking.

Assess Age & Condition

If your relief valve is more than 5-7 years old, replacement may be the fix if other issues are ruled out.

Repairing or Replacing the Relief Valve

Once the source issue is identified, you can proceed with fixing the problem:

Adjust Home Water Pressure

Install a whole house pressure reducing valve if pressure exceeds 80 PSI.

Flush Valve & Pipes

Vinegar flush to dissolve mineral buildup deposits inside valve and connected piping.

Replace Valve Seal/Gaskets

Consider replacing worn rubber gaskets if the metal valve body remains in good shape.

Install Thermal Expansion Tank

Adding an expansion tank on the cold water supply line can remedy pressure relief dripping issues.

Replace Defective Relief Valve

If troubleshooting tips don't solve the problem, replace the entire pressure relief unit with a new valve.

Preventing Future Leaks

You can take several proactive steps to avoid needing relief valve repairs down the road:

• Maintain proper water pressure around 50-60 PSI
• Drain and flush tank annually to remove mineral deposits
• Ensure proper thermal expansion controls in place
• Replace relief valve every 5-7 years as routine maintenance
• Check and test valve 1-2 times per year

When to Call a Professional

In certain circumstances it best to call a licensed plumber for assistance with a leaky relief valve:

• Help diagnosing root cause if troubleshooting proves difficult
• Adjusting home main water pressure
• Replacing defective pressure relief valves
• Evaluating and servicing full hot water heater system

FAQs

What PSI should a relief valve be set at?

Most residential pressure relief valves are preset to open between 75-150 PSI. Typical rating is 150 PSI and 210degF.

Where is the relief valve located?

It is installed directly on the hot water tank itself, near the top. May have a discharge pipe directing water to a drain pan or floor drain.

Is a small leak a concern?

Even a minor drip can signal issues with water pressure, thermal expansion, or valve failure - so don't ignore it. Address the problem early.

What type of new valve should I buy?

Look for a valve with the same pressure rating (150 PSI), capacity (BTUs), and thread type. Brass or stainless steel bodies last longest.

Dealing with a leaky hot water tank pressure relief valve can seem frustrating, but armed with the right information you can troubleshoot the issue and take appropriate repair steps. Leverage the valve testing, flushing, component replacement, and preventative maintenance tips outlined above to stop the leak and minimize risk of a hazardous pressure explosion.

Stay safe, save water and energy, and preserve your water heating system performance by promptly addressing relief valve dripping problems as soon as you notice them. With proactive valve replacements and annual tank flushing, you can avoid unplanned mid-life leaks and keep pressure regulated properly for maximum operational efficiency and safety.