Water Heater Expansion Tank: What It Is & When You Need One
Basics of Water Heater Expansion Tanks
Have you ever turned on your faucet and noticed a sudden drop in water pressure, or heard strange sounds coming from your water heater? If your water heater has a water tank, these signs could indicate that your water heater is experiencing the effects of thermal expansion, a naturally occurring process that can lead to a buildup of pressure in your water heater and can cause damage over time.
Luckily, there’s an easy fix to this common issue: a water heater expansion tank or “thermal expansion tank.” This small, essential component can help protect your plumbing system, prevent damage that can lead to costly repairs and extend the lifespan of your water heater.
Keep reading to learn more about water heater expansion tanks, how to tell if you need one and tips for a seamless installation process.
What Is a Water Heater Expansion Tank?
At its core, a water heater expansion tank is a small container that connects to your cold water line. Water heaters with a tank—as opposed to tankless water heaters—naturally experience thermal expansion, which creates a buildup of pressure that can cause long-term damage to your plumbing system.
Water heater expansion tanks can help relieve that pressure by giving the resulting excess water a place to go. Since tankless water heaters heat water on demand, they typically aren’t negatively impacted by thermal expansion.
What Is Thermal Expansion and How Does It Affect Water Heaters?
To fully understand the benefits of adding a water heater expansion tank, it may help to learn the basics of how thermal expansion affects your water heater:
- Cold water flows into your water heater tank.
- Your water heater raises the temperature of the water inside the tank.
- As the water gets hotter, it expands, based on the principles of thermal expansion.
- Modern “backflow” regulations require plumping systems to have check valves.
These check valves prevent the excess water from flowing back into your plumbing system. - The water continues to expand, building pressure inside the tank.
- Over time, this pressure begins to damage the valves, plumbing or the water heater itself. If you’re hearing strange noises inside your water heater, you may be hearing the strain the water tank is experiencing from all the pressure.
- When you install a water heater expansion tank, the water expands and overflows into the tank. This relieves pressure and helps prevent your water tank and plumping system from being damaged.
As you can see, a water heater expansion tank is a simple but effective solution. A water heater expansion tank provides a dedicated space for expanded water, regulating pressure inside the tank to prevent costly damage and extend the lifespan of your water heater.
How to Tell If You Need a Water Heater Expansion Tank
Not every home needs a water heater expansion tank, but certain conditions make it a smart investment. Here are some common scenarios where an expansion tank is essential.
You may need a water heater expansion tank if…
- You have a closed plumbing system. If your home has a closed plumbing system with check valves that prevent water from flowing back into the main supply line, thermal expansion can cause significant pressure buildup. Installing an expansion tank can help manage this pressure, protecting your plumbing and water heater from potential damage.
- You notice common signs of pressure buildup. If you notice signs that indicate building pressure, your system may be stressed and could benefit from an expansion tank. Skip to the next session to view a list of common signs that may indicate a pressure buildup.
- Your water heater is fairly new. Newer water heaters are designed for higher efficiency, which can lead to increased pressure. Adding an expansion tank allows you to enjoy the benefits of modern, energy-saving water heaters without the risk of pressure-related damage.
- You want to upgrade the energy efficiency of your water heater. By managing pressure changes inside the tank, water heater expansion tanks can help your water heater operate more efficiently, leading to potential energy savings in the long run.
Signs of Pressure Buildup in Your Water Heater
Deciding whether your water heater needs an expansion tank often comes down to recognizing the signs of pressure buildup in your system. Thermal expansion can create excess pressure, which may lead to various issues over time.
Keep an eye out for these common signs that indicate it may be time to install an expansion tank:
- A noticeable, sudden drop in water pressure, especially when using hot water.
- Banging or knocking sounds coming from the water heater.
- Dripping or leaking pressure relief valves.
- Small leaks around the base of the water heater.
- The water heater frequently cycles on and off.
- Recurring need for pressure-related repairs.
If you notice any of these signs, it’s a good idea to consider adding an expansion tank to help protect your water heater and ensure the longevity of your plumbing system.
How to Install a Water Heater Expansion Tank
If you’ve assessed your water heater setup and decided to add a water heater expansion tank, it’s time to pick out a tank and begin the installation process. Proper installation is essential for ensuring your water heater operates safely and efficiently.
Follow the steps and tips below to get the most from this upgrade:
1. Determine the right size.
- Identify your water heater’s capacity. Check the label on your water heater to see if it lists its maximum capacity. Or look for the model number and find the instruction manual online.
Bring this information with you when it’s time to pick out an expansion tank. You’ll need to select a model that says it’s compatible with your water heater’s capacity.
- Measure your water pressure with a pressure gauge. You can find a pressure gauge at most hardware stores that measures the water pressure in your home’s plumbing system. Don’t skip this step—expansion tanks are rated based on both the water heater capacity and the incoming water pressure.
- Consult the manufacturer’s guidelines. Each manufacturer provides specific recommendations for sizing based on your system’s parameters. Be sure to review these guidelines to select the correct expansion tank. If you can find the model number on your water tank, you can usually find the corresponding user manual online.
🛟Safety Tip: If you’re unsure about sizing, consult a professional plumber who can assess your specific needs and recommend the appropriate tank size.
2. Find a suitable location for the new tank.
- Identify the cold water line. The cold water line is directly connected to your water heater. During installation, you’ll disconnect the waterline from the water heater and connect it to the expansion tank instead.
- Make sure it’s accessible: Choose a location that’s accessible for future maintenance or inspections. The tank should be positioned so that it’s supported and secure but also easy to reach.
- Choose a spot with plenty of room for proper placement. Avoid installing the expansion tank in a confined space that makes it difficult to inspect or service. A well-ventilated area is preferable.
You’ll need enough space to directly connect the water line to the expansion tank instead, which will then be connected to your water heater. The water will flow from the cold water line, through your expansion tank, and into your water heater.
This placement allows the expansion tank to absorb the pressure created when the water is heated, instead of pushing against the check valve on the water line.
3. Install the Expansion Tank
🛟Safety Tip: The Consumer Product Safety Commission (CPSC) recommends professional installation to ensure safety and compliance with local building codes. If you’re not experienced with plumbing, play it safe by hiring a professional for the installation.
- Gather the necessary tools. Before beginning, make sure you have the necessary tools, including a pipe wrench, Teflon tape and a pressure gauge. You’ll also need any connectors required to attach the tank to the existing plumbing.
- Shut off the water supply. Turn off the main water supply and drain the water heater to reduce pressure in the system. This step is crucial for safe installation.
- Attach the tank to the cold water line: Using the appropriate fittings, attach the expansion tank to the cold water line. Then, connect the expansion tank to the water heater. Be sure to use Teflon tape on the threads to ensure a secure, leak-free connection.
4. Test the Installation
- Check for leaks. Turn the water supply back on and inspect the connections for any leaks. Tighten any fittings as needed.
- Measure the system pressure. Use a pressure gauge to measure the system’s pressure after the expansion tank is installed. The pressure should be within the range recommended by the manufacturer.
🛟Safety Tip: If you notice fluctuating pressure or any unusual noises after installation, contact a professional to inspect the system and make any necessary adjustments.
Maintenance and Lifespan of Water Heater Expansion Tank:
- Inspect regularly. Every few months, check the expansion tank for signs of wear, corrosion or waterlogging. Regular maintenance can help prevent issues before they become serious.
- Replace as needed: Expansion tanks typically last around six years, but this can vary based on usage and water quality. Replace the tank if you notice any decline in performance.
🛟Safety Tip: Consider scheduling an annual inspection by a qualified technician to ensure your water heater and expansion tank are functioning correctly.
By following these steps, you can ensure that your expansion tank is properly sized, installed and maintained, helping to protect your water heater and plumbing system.
FAQ:
1. Is it mandatory to have an expansion tank with every water heater?
While it’s not always required, an expansion tank is highly recommended, especially if your home has a closed plumbing system. Without an expansion tank, thermal expansion can cause pressure to build up in your water heater, leading to potential damage.
Installing an expansion tank helps prevent these issues, protecting both your water heater and your plumbing system from unnecessary stress.
2. How do I know the right size of expansion tank for my water heater?
The correct size of the expansion tank depends on your water heater’s capacity and the incoming water pressure in your home. To ensure you choose the right size, check the manufacturer’s guidelines for both your water heater and the expansion tank.
If you’re unsure, consulting a professional plumber is a smart move. They can assess your system and recommend the appropriate expansion tank size based on your specific needs.
3. Can I install the expansion tank myself?
The CPSC recommends hiring a contractor to complete a professional installation to ensure safety and compliance with local building codes. If you’re experienced with DIY plumbing projects, installing an expansion tank might be within your capabilities.
However, because proper installation is critical for safety and efficiency, it’s in your best interest to hire a professional. A licensed plumber can ensure the expansion tank is correctly sized, installed and compliant with local building codes, giving you peace of mind that your system is protected.
Wrapping Up: Water Heater Expansion Tank Essentials
A water heater expansion tank is more than just an add-on—it’s a crucial component that helps safeguard the efficiency, safety, and longevity of your water heater. By managing the pressure caused by thermal expansion, an expansion tank can prevent costly damage and extend the life of your system.
Whether you’re upgrading to a more efficient water heater, noticing signs of pressure buildup or simply looking to protect your investment, adding an expansion tank is a wise, proactive choice.
Regular maintenance and professional inspections can further ensure your system operates smoothly, keeping your home comfortable and your energy bills manageable.
If you’re an EPB customer and you have questions about whether an expansion tank is right for your home, don’t hesitate to contact the EPB Energy ProsSM. We’re available for free consultations over the phone and by chat, where we’ll answer your energy questions, show you how to qualify for incentives on energy-saving home upgrades and help you find all the ways to save on your energy costs. Learn more.
