What is a thermal expansion relief valve?

The thermal relief valve relieves the over-pressure in a piping system of fluid due to temperature rise. In most cases, the thermal relief valve is used when a liquid is blocked in a pipe, and the pipe is exposed to sunlight. The pressure relief valve limit the system pressure to a specific set level.

Consequently, what is an expansion relief valve?

The Expansion Control Valve (ECV) is designed to relieve the increase in pressure caused by the water expansion during the normal heating cycle. This will relieve cold water, not hot water, during the heating cycle saving energy and increasing the life of the Pressure Temperature Relief valve (PTR).

One may also ask, what is an expansion valve on a water heater? A thermal expansion control valve is essentially a pressure relief valve installed at a water heater to prevent forming excessive pressures in the closed loop of water supply piping and water pressure tank when water is heated at the water heater.

Additionally, how does an expansion relief valve work?

As the water heater heats the water, it expands, which builds up pressure in what is now essentially a closed system. When the pressure builds up enough, the T&P relief valve on the water heater just does it's job and relieves the excess pressure by leaking a little water.

What causes a water heater relief valve to open?

Causes and fixes Pressure: If there is no allowance within the system to absorb the increase in pressure such as an expansion tank or a thermal expansion valve and all the taps are closed, the relieve valve will open and discharge water until the pressure drops to below the setting of the relief valve.

35 Related Question Answers Found

How often should you test pressure relief valves?

It is recommended that you test pressure relief valves at least once every six months, especially to reduce leakage caused by the buildup of minerals and corrosion. Scheduling pressure relief valve testing every six months enables you to troubleshoot issues and fix them promptly.

Do I need a pressure relief valve?

Installing a pressure relief valve (PRV) before your tankless water heater is not only required in some regions depending on where you live, but is also a very important safety feature. The increased water pressure opens the pressure relief valve and water can escape to the exterior.

How long does a pressure reducing valve last?

20 years

Why is hot water coming out of my overflow pipe?

Hot water systems

Water expands when heated, pressure builds up in the tank and is released through the overflow pipe. So water dripping or running from the valve can be a sign of a normal, functioning system. However, not all leaking overflow pipes are occurring due to normal pressure build up.

What does a pressure relief valve look like?

The pressure relief valve on your water heater will look like a small pipe extending away from the tank, normally aimed downward. As the name suggests, it helps to relieve the pressure that can build up in the water heater unit from the hot interior temperature.

Where is the pressure relief valve?

Where is the Water Heater Pressure Relief Valve? The T&P valve is usually located high on the side or on top of the tank. It's connected to a pipe that runs down the length of the water heater and stops a few inches above the floor.

How much does it cost to replace a pressure relief valve?

Pressure Relief Valve - $20-$200

A replacement valve costs around $20 and calling in a professional could bring your cost up to $200. This isn't a steep cost to ensure proper diagnosis and installation. The pressure relief valve is there as a safety measure in case the pressure inside the tank gets too high.

How do you adjust a pressure relief valve?

With a slotted screwdriver, turn the screw in the center of the knob clockwise, until flow can be heard escaping from the internal valve. Slowly turn the screw counterclockwise until the flow from the relief valve stops. Turn the screw an additional 1/8 to 1/4 turn counter-clockwise. Replace the silver cap in the knob.

What is the symbol for a check valve?

An arrow or the symbol for any type of check valve (a fluidic/pneumatic logic symbol) on the outside of the body indicates flow direction.

How does a pressure valve work?

What is a Pressure Reducing Valve? Pressure reducing valves are devices that work directly to slow down the pressure of water flowing into your home. They are installed on the main water line next to the shut-off valve. Water from the water main goes into the valve on one side.

How do you test an expansion tank?

How to Tell If an Expansion Tank is Working

Tap on the tank. It should be hollow about half way up.
Check the temperature by feeling the top and bottom of the tank. The tank should be warm on the bottom and cool on the top if it is working properly.
Use an air gauge to check the pressure inside the tank.
Check to see if your release valve is spurting water.

How do I fix a leaking pressure relief valve?

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.

Should I install an expansion tank on a water heater?

When is it required? An expansion tank is always highly recommended if you have a 'closed-loop system' caused by any kind of check valve or pressure regulating valve installed on your house's water supply line. A common analogy compares having high water pressure in your home to having high blood pressure.

What is a cold water expansion valve?

Cold Water Expansion Valves, Also Called Energy Saving Valves. The Cold Water Expansion has 2 roles in this situation, it's a safety mechanism that releases excess pressure from your hot water cylinder as it heats up to avoid over pressurizing protecting the system as a primary means of release.

What causes expansion tanks to fail?

The loss of air cushion in the expansion / compression tank means that at each heating-on cycle the system pressure can be too high, causing the temperature/pressure relief valve to spill. Air in the hot water heating system can cause loss of heat: air in baseboards radiators keeps hot water out - they don't get hot.

Why is my hot water heater leaking from the pressure relief valve?

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.

Where does an expansion tank go on a water heater?

Your expansion tank can be anywhere on your plumbing system and does not need to be installed in close proximity to the water heater. It is most commonly installed using a “T” at the cold inlet to the water heater. But, functionally, it can be installed anywhere on the cold inlet line.