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Water Heater Pressure Too High? Adjust That T&P Valve

If you've noticed your water heater's T&P (temperature and pressure) relief valve dripping or even spraying water, it likely means the pressure inside your hot water tank has gotten too high. This is a warning sign that something needs adjustment to avoid safety hazards or costly water damage.

What Causes High Water Heater Pressure?

There are a few root issues that create abnormally high pressure in your hot water system:

Excessive Thermal Expansion in Closed System

Heating water causes it to expand in volume. In a closed system with no place for expanding water to go, the pressure steadily rises. If there is no thermal expansion tank or the tank is waterlogged, pressure can spike over the T&P valve's limit causing it to open.

hot water heater pressure relief valve keeps opening

Water Pressure Entering Home Over 150 PSI

Most T&P valves are set to open above 150 PSI. If your home's water pressure exceeds this threshold, the valve will leak trying to protect the tank from excessive pressure damage until the pressure drops below 150 PSI again.

Waterlogged Tank

If too much water enters the tank, perhaps due to a stuck open fill valve, the extra volume of water pushes up on the existing water - raising pressure beyond the valve's limit.

Sediment Buildup

Over time, mineral deposits and sediment can accumulate at the bottom of the tank. This limescale debris can prevent the T&P valve from fully closing and resealing, resulting in small pressure leaks.

Symptoms of High Pressure

How do you know if pressure is too high in your hot water system? Here are some key signs:

Dangers of Ignoring a Leaking T&P Valve

It may be tempting to cap or plug a leaky T&P valve. However, this safety mechanism opens for an important reason - to prevent catastrophic tank failure from extreme pressure spikes. Ignoring this warning sign can have serious consequences like:

Instead of disabling this essential safety valve, the goal is to properly adjust the underlying root cause of high tank pressure.

How To Adjust Water Heater Pressure

For Thermal Expansion

To handle expanded hot water volume in a closed system, you need to give that water somewhere to go. This is done by:

  1. Fully draining the tank
  2. Installing an thermal expansion tank

The expansion tank provides extra air-filled space to absorb heating induced water expansion without pressure buildup. Just make sure the new tank isn't already waterlogged itself.

For High Home Water Pressure

If water pressure entering your home is consistently over 150 PSI, a whole house pressure reducing valve is needed. This special valve lowers your home's water pressure down below the T&P valve's pressure limit. With pressure entering the tank safely reduced, the relief valve won't need to open.

For Waterlogged Tank

To resolve excess water volume, you'll need to:

  1. Drain the tank down to the proper fill level
  2. Adjust or replace the fill valve if stuck open

Removing the excess water alleviates pressure on the existing water, giving the T&P valve enough space to close properly.

For Sediment Buildup

To clear out accumulated mineral deposits:

  1. Flush the tank by draining fully then refilling
  2. Clean or replace the T&P relief valve itself

This should allow the valve to fully seal again once pressure drops to normal.

When To Replace a T&P Valve

If your T&P valve is over 10 years old, shows visible corrosion, no longer seals properly, or continues leaking after resolving pressure issues - replacement is likely needed. The spring mechanism inside that forces the valve open and closed can weaken over time. Replacing an aging valve restores normal function.

Preventing High Pressure Problems

Once resolved, there are some maintenance tips to prevent repeat high pressure situations:

Taking these preventative steps reduces the chances of that T&P valve leaking again!

If your water heater's pressure relief valve is dripping or spraying water - crucial safety adjustments are needed. Left ignored, high tank pressure can eventually cause explosion hazards. By properly addressing the root issue whether expansion, water volume, home pressure, or deposits - you can safely stop that leak and keep your T&P valve working properly.