How do I know if I need a new expansion tank?

Author: Jackson Becker  |  Last update: Tuesday, August 19, 2025

Check the Air Valve All expansion tanks feature an air valve that looks similar to the valve on the tires of a car. You can check whether your tank is in good condition by bleeding some air from the valve. If air comes out, your tank is working. However, if water bleeds out, there is a rupture in the tank bladder.

How can you tell if an expansion tank is bad?

If air comes out, your expansion tank is working. If nothing or water comes out your tank is bad and needs to be replaced. When a hot water expansion tank works correctly, you will probably see no problems with leaks and other issues.

When should I replace my expansion tank?

Expansion tanks will normally wear out after anywhere from 5-10 years. To extend their service life as much as possible, it's vitally important to match your expansion tank's air pressure to your house's water pressure.

How much should it cost to replace an expansion tank?

A water heater expansion tank costs $150 to $450 on average, with a national average of $325. The total cost depends on the size and type of tank. A water heater expansion tank costs an average of $325 to install, and most people pay between $150 and $450 for the task.

What is the rule of thumb for expansion tanks?

The general rule of thumb for proper capacity of expansion is 12% of total coolant volume for draw down and 6% of the total volume for thermal expansion. Drawdown capacity is the amount of coolant that can be lost before air reaches the water pump and is introduced into the system.

What is a thermal expansion tank, and why do you need one?

What is the life expectancy of an expansion tank?

However, on average, an expansion tank can last 5 to 10 years or even longer if properly maintained and inspected regularly. It is recommended to check the expansion tank for signs of damage or wear, such as leaks or rust, at least once a year and replace it if necessary.

Do you have to drain a water heater to replace an expansion tank?

Whether you're adding a new expansion tank to an existing water heater or you are replacing a water expansion tank, you will need to drain your water heater. Various pipe connections have to be made and you don't want water to end up all over the floor, so drain the water heater before your work begins.

What happens when a well expansion tank fails?

Potential for Water Damage:

Water damage to the surrounding region may result from a leaky tank or an overused pump that finally breaks. It might damage your house's walls, flooring, and foundation, necessitating costly repairs.

Who fixes expansion tanks?

You must call a plumber immediately if you notice any water leaking from your expansion tank. They will evaluate the issue and ensure it is properly repaired or replaced before further damage occurs.

Do expansion tanks lose pressure over time?

With time, the water absorbs air, and when that happens, the tank loses some of its pressure. Addressing this problem and restoring your air pressure means recharging the tank.

How do you tell if you have a closed water system?

If your home has a Backflow Prevention Device, Pressure Reducing Valve (PRV), re- circulating pump with check valve, or anything else that prevents backflow of water installed, its plumbing system is considered "closed".

When should I replace my expansion valve?

Replacing Your AC Expansion Valve

The more you use your air conditioner, the faster your expansion valve wears out. However, with moderate use and regular air conditioner maintenance, the valve should last 5 to 10 years. Always replace your expansion valve quickly.

How do I know when to replace an expansion tank?

Signs It's Time to Replace an Expansion Tank

If the tank is no longer effectively maintaining or controlling this pressure, it indicates a malfunction. Loss of pressure control could mean that the internal air bladder or diaphragm has ruptured, or that the tank has lost its pre-charge.

Should my expansion tank be full of water?

Your expansion tank should be half full of water and air. Using a metal object, tap the top and bottom half of the tank. The sounds should be quite different, which indicates that your tank is filling up the way it should.

How do you check a well expansion tank?

4 Steps To Check The Pressure Tank Of A Water Well
  1. Turn the power to the wells pump off by flipping the designated breaker at the electrical panel to the off position.
  2. Drain the pressure tank. ...
  3. Locate a pressure gauge (tire gauge) Use the gauge to check the tank's pressure.

What is the life expectancy of a well expansion tank?

Average Lifespan

The typical lifespan of well pressure tanks is 10 to 15 years, though this can vary depending on the tank's quality and maintenance. Higher-quality tanks can last 5 to 30 years, with the average being around 15 years.

How much does it cost to replace a well expansion tank?

Replacing a well pressure tank costs $500 on average, but it can cost between $300 and $700, depending on the tank's size, capacity, and labor costs for professional installation.

Can I replace my own well pressure tank?

Chances are it's time to replace your water well pressure tank. While this may sound like a job for a professional plumber, this is also something you can do yourself at home if you're handy with DIY plumbing.

How to test for a bad expansion tank?

A simple yet effective way to assess the condition of your expansion tank is by giving it a light tap. If the tank produces a hollow sound, it indicates that the tank is still in good working order. On the other hand, a thudding or dull sound suggests that the tank has been compromised and may require attention.

How often should you drain an expansion tank?

Water will get inside of the system, of course, which means that you are going to need to drain expansion tank to make sure that the pressure that the tank absorbs is always at an optimum. This task shouldn't take very long, and should be done a couple of times a year by you or a professional.

Can I replace my own expansion tank?

If you're not experienced working with gas or electric heating systems, you shouldn't run the risk of causing a serious incident by attempting to work on your hot water expansion tank. There's a reason that people need a license to carry out such work, it's dangerous and can cause major problems.

How do I know if my expansion tank cap is bad?

Overflowing Reservoir

To prevent the tank from overflowing, the radiator cap should normally release a little pressure from the system. A faulty cap will not release the pressure from the system, leading the reservoir overflowing.

What PSI should an expansion tank be set at?

Expansion tanks are pre-charged with a 40 PSI air charge. If the inlet water pressure is higher than 40 PSI,the expansion tank's air pressure must be adjusted to match that pressure but must not be higher than 80 PSI. *Highest recorded inlet water pressure in a 24-hour period of regulated water pressure.

How do I check my tank level?

Using a dipstick or measuring tape: This is a simple and inexpensive way to check the liquid level in a tank. A dipstick or measuring tape is inserted into the tank, and the level of liquid is read from the markings on the dipstick or tape.

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