If your home has a water heater, it also has an expansion tank. The expansion tank is a small cylinder that helps to regulate the pressure in your water heater. Over time, the expansion tank can become damaged or worn out.
When this happens, you’ll need to replace it.
What Is This Tank? How to Replace and Maintain a Water Heater Thermal Expansion Tank
- The expansion tank is an important part of the water heater, as it helps to protect against excessive pressure in the system
- If the expansion tank becomes damaged or leaks, it will need to be replaced
- Here are a few steps on how to replace a water heater expansion tank: 1
- Shut off the water supply to the home and turn off the power to the water heater
- Drain the water from the tank by opening up the drain valve at the bottom
- Disconnect any pipes or fittings that are attached to the old expansion tank and remove it from its location
- Install the new expansion tank in the same location as the old one, making sure that all connections are tight and secure
- Turn on the power and water supply to the unit and allow it to fill up with water before turning on any appliances or fixtures that use hot water
Expansion Tank for Water Heater Required by Code
If you have a water heater, you may be wondering if an expansion tank is really necessary. The answer is that, in most cases, it is required by code. Here’s a closer look at what an expansion tank is and why it’s important to have one installed.
An expansion tank is a small holding tank that helps to equalize pressure in the water heater. When water heats up, it expands and can cause the pressure in the system to increase. This can lead to problems like burst pipes or leaks.
An expansion tank provides a place for this excess water to go so that the pressure remains balanced and under control.
Most jurisdictions require that an expansion tank be installed on any new or replacement water heater. So, if you’re planning on getting a new water heater or replacing an old one, be sure to factor in the cost of an expansion tank as well.
It’s usually a fairly inexpensive addition but it could save you a lot of headaches (and money) down the road!

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Can I Install an Expansion Tank Myself?
If you’re handy with tools and have some basic plumbing knowledge, then installing an expansion tank yourself is certainly possible. However, there are a few things to keep in mind before undertaking this project.
First, be sure to purchase the correct size expansion tank for your home.
These tanks are typically classified by the amount of water they can hold – so make sure you know how much water your home’s plumbing system can hold before selecting a tank.
Next, you’ll need to install the tank in a location where it can properly do its job. Expansion tanks must be installed upstream of the cold water shut-off valve and should never be installed in an attic or crawlspace (since these locations can get very hot or very cold).
The ideal location for an expansion tank is on a wall near your home’s main water line.
Once you’ve selected and prepared a location for your expansion tank, installation is relatively straightforward. First, shut off the main water supply to your home.
Next, connect one end of a lengths of pipe to the cold water shut-off valve and run it up to the expansion tank location. Secure the piping to the wall using brackets or clamps (be sure not to overtighten!). Finally, connect the expansion tank to the piping and open up the main water supply again.
That’s it! With just a little bit of planning and elbow grease, you can easily install an expansion tank in your home without having to call in a professional plumber.
Do You Have to Drain a Water Heater to Change the Expansion Tank?
No, you don’t have to drain a water heater to change the expansion tank. The expansion tank is there to absorb any excess pressure that may build up in the system. If you find that your water heater is starting to make strange noises or is leaking, then it’s probably time to change the expansion tank.
How Often Do You Change an Expansion Tank on a Water Heater?
An expansion tank is a pressure-reducing tank installed between the water heater and the main water supply line. The expansion tank prevents the water in the system from becoming pressurized when the temperature of the hot water rises. It also provides a place for the expanded water to go so that it doesn’t backflow into the cold water line and cause your fixtures to spew out scalding hot water.
The size of an expansion tank is determined by the volume of water in your system and the amount that your system’s pressure will increase when heated. Most homes with standard 40 or 50 gallon (151 or 189 liter) tanks will need a 2 gallon (7.6 liter) expansion tank.
The frequency with which you’ll need to change your expansion tank depends on its location, how often it’s used, what type of maintenance you perform on it, and what kind of environment it’s in.
If it’s located outdoors, it may only last 3-5 years before needing to be replaced due to weathering and corrosion. Indoors, properly maintained tanks can last 10-15 years or more.
If you’re not sure how old your current expansion tank is or whether it needs to be replaced, have a professional plumber inspect it as part of your regular maintenance routine.
How Much Does It Cost to Replace an Expansion Tank on a Water Heater?
An expansion tank is a small, pressurized tank that is installed in the cold water line near your water heater. The expansion tank helps to protect your home’s plumbing system from the damaging effects of thermal expansion. Thermal expansion occurs when water is heated and expands in volume.
This increase in volume can cause pressure to build up in your home’s plumbing system, which can damage pipes and fixtures. An expansion tank provides a place for this expanded water to go so that it doesn’t damage your home’s plumbing.
The cost of replacing an expansion tank on a water heater will vary depending on the size of the tank and the type of water heater you have.
Expansion tanks are typically priced between $40 and $200.
Conclusion
If your home has a water heater, there’s a good chance it also has an expansion tank. An expansion tank is a small tank that helps to maintain the water pressure in your home by compensating for the expanding water as it heats up. Over time, these tanks can become corroded or damaged, and will need to be replaced.
Here’s how to replace a water heater expansion tank:
1. Shut off the power to your water heater. This is usually done at the breaker box.
2. Drain the water from your water heater. There should be a drain valve near the bottom of the tank that you can open to do this.
3. Disconnect the old expansion tank from the cold water supply line and remove it from your home.
4. Install the new expansion tank in its place, connecting it to the cold water supply line with copper or plastic tubing (depending on what your home has). Make sure all connections are secure and there are no leaks before turning the power back on to your water heater!