Best Water Heater Expansion Tanks in 2023

Do you want to protect your plumbing system from thermal expansion risks? Then, investing in a high-quality water heater expansion tank is something to consider.

If you have a closed plumbing system, a tank water heater will put pressure on your pipes due to thermal expansion. The water heating process in a closed system can cause this problem. Both boilers and water heaters may have a risk of damage if you haven’t taken preventive measures.

So, you can buy a water heater expansion tank as a safety device to solve this problem. But which device is perfect for your needs? We’ve carefully made some picks to help you choose the best thermal expansion tank.

Top 5 Water Heater Expansion Tanks

1. Amtrol T-5 THERM-X-SPAN Expansion Tank

Amtrol T-5 THERM-X-SPAN Expansion Tank

  • Capacity – 2 gallons
  • Material – Steel
  • Weight – ‎4.8 pounds

Amtrol is a reliable brand known for designing water heater expansion tanks and other related accessories. The Amtrol T-5 THERM-X-SPAN is an affordable device that ensures easy installation: the tank helps minimize energy and water waste, so your water meter will show a comparatively low consumption. Even with modern plumbing codes, you can use this tank without concerns.

Amtrol has used a steel shell to design the T-5 expansion tank. The tank includes a rubber diaphragm and a plastic liner, and the brass system connection gives you lasting value. The operating temperature should not be above 200 ℉, and the working pressure needs to be around 150 PSIG.

You can find a pre-pressured inflatable balloon, but you may need to manage a little amount of pressure to hit your target for the tank size you have.

  • Well-designed expansion tank
  • Threading in good shape
  • Secure relief valves
  • No insight indicator cap

2. HIGHCRAFT GUU7 Thermal Expansion Tank 

HIGHCRAFT GUU7 Thermal Expansion Tank

  • Capacity – 2.1 gallons
  • Material – Carbon steel
  • Weight – ‎5.29 pounds

HIGHCRAFT GUU7 is another high-quality water heater thermal expansion tank to protect your heating system. It prevents dangerous pressure accumulation inside the plumbing system and reduces the risk of leaks. While the carbon steel material has increased durability, there is a polypropylene liner and polyester coating that protect your tank.

There is a plastic screw-on cap at the bottom to safeguard the valve stem and manage diaphragm air pressure. The maximum temperature of the thermal expansion tank can be up to 210 ℉, while the operating pressure is 150 PSI.

You can save water and energy with HIGHCRAFT water heater tanks.

  • Perfect construction
  • Rust-resistant
  • Leak-proof
  • Some customers advised there was a dent on the thermal expansion tank

3. PROFLO PFXT5 2 Gallon Thermal Expansion Tank

PROFLO PFXT5 2 Gallon Thermal Expansion Tank

  • Capacity – 2 gallons
  • Material – Carbon steel
  • Weight – ‎5 pounds

You can choose this thermal expansion tank if you have a potable hot water system. Like other safety devices, the PFXT5 is capable of controlling pressure buildups to make your water heater long-lasting. As the PFXT5 is a diaphragm-type tank, it works like a bladder tank: it’s intended to keep air and water separate in the vessel.

The tank is made of high-grade, durable stainless steel, and is rust and corrosion-resistant. The factory pre-charged pressure is 40 PSI, and the maximum pressure handled by the tank is 150 PSI. The size of the end connection is 3/4″ SS NPTM.

  • No relief valve spills
  • Increases the life expectancy of your water heater
  • Quality build
  • No issues found

4. Zurn XT-8 – Thermal Expansion Tank

Zurn XT-8 - Thermal Expansion Tank (1)

  • Capacity – 2.1 gallons
  • Material – Steel
  • Weight – 5.1 pounds

If you’re looking for a thermal expansion tank for residential applications, Zurn® XT is the right choice. The XT series products are known for their reliable design and good acceptance volume. Due to the epoxy coating, the tank is thermal resistant. Whether it’s a scorching sunny day or the weather is chilly, the tank will have no damage because of this coating.

The pre-pressure rating is similar to what we’ve found in other thermal expansion tanks. The maximum temperature that can be endured by the tank is 200 ℉. Steel has been used for the tank due to its wear resistance and good thermal expansion capability.

Inside the tank, there is a polypropylene liner to protect the material from water damage. So, try out this tank to keep your heater safe from water pressure.

  • Best for installing on potable water lines
  • Low-lead law compliant
  • Well-tested design
  • Not easy to install, according to some users

5. BackStop A101 Thermal Expansion Tank

BackStop A101 Thermal Expansion Tank

  • Capacity – 2 gallons
  • Material – Stainless steel
  • Weight – 5 pounds

Designed to protect your hot water system, this thermal expansion tank has a reliable construction with the residential diaphragm model. You have to install the tank between the water heater and backflow preventer to accept the potable hot water. The pressure of the systems will be below the settings of the relief valves.

The tank is designed for indoor use. However, 304 stainless steel construction ensures high durability. The manufacturer has integrated a butyl rubber diaphragm, as this material is flexible and has low gas permeability. The MIP connection has a dimension of 3/4″.

  • Made of quality material
  • Prevent over-pressurization
  • Pre-pressured
  • No complaints

Guide to Buying the Best Water Heater Expansion Tank

A water heater expansion tank works as a secondary tank designed for safety purposes. It lets you alleviate excess pressure and overflow by preventing damage to water heaters.

Different Types of Thermal Expansion Tanks

  • Bladder expansion tank – This looks almost like a regular steel tank. However, it has a membrane to keep air and water separated. Additionally, it prevents the system from absorbing air and reduces the risk of corrosion on your water heater tank. There’ll be no water-logging problems due to this tank.
  • Compression tank – This is a plain, steel tank installed on the air separator. The main purpose of this tank is to ensure some space for the expanded water, because of the higher temperature. When heated, water volume increases. The expansion tank allows the system to provide more space for this water.

Thermal Expansion Tank Size

Sizing is a vital aspect for those who buy thermal expansion tanks. You may think of buying oversized expansion tanks because they don’t cause too much pressure. However, if you’ve chosen a smaller model, you may find a lot of problems.

Smaller expansion tanks cause strain on your system: a water heater won’t last long if the tank is too small. Hot water will be out of control and will be discharged from the relief valve. To protect your water heating machine, choose a thermal expansion tank of the right size.

Water Heater Capacity

Another thing to be checked while buying a thermal expansion tank is the heater capacity. Most manufacturers clearly mention the capacity of the tank. Check the label before purchasing the tank: the water heater capacity ranges from 40 to 55 gallons.

Supply Pressure

Measured in PSI, the water heater pressure is another significant factor for buyers. The PSI may range from 50 to 60. It will help you pick the right thermal expansion tank.

When to Install a Thermal Expansion Tank

You need to check for a few common signs to decide between buying a thermal expansion tank. You could purchase a thermal expansion tank when:

  • The water heater has high pressure.
  • You hear a rattling noise or odd sound from the heater.
  • Water drips or leaks from your system.
  • Your system is too old.

Tips and Tricks for Using Thermal Expansion Tanks

The biggest challenge in adding an expansion tank to a water heater is to find room. You’ll need to use different pipes and accessories to install the tank: the copper line may need to be replaced for this purpose. You need to add extra pipes and elbows to the water pipe. Remember to make sure you have enough room for this.

To prevent overheating, it’s better to install your tank 1 to 2 feet away from the water heating system. Some professional plumbers recommend using a new dielectric union while adding a tank to the water heater.

When buying and installing a thermal expansion tank, keep in mind:

  • The piping connection and the expansion tank should be vertical to each other. This will alleviate stress on the connections of your tank.
  • Tanks are mostly available in pre-charged condition. However, don’t assume that it’s the right pressure: taller pipes need higher air pressure.
  • When the water temperature is 45 ℉, the diaphragm expands.
  • There’s no need to have multiple connection points for the same piping.

Remember these details when buying a thermal expansion water tank.

Best Brands of Water Heater Expansion Tanks

  • Amtrol – Amtrol is a well-known brand that’s gained popularity for designing different residential and commercial plumbing accessories. It has a special Quality Management System to provide flawless products for customers.
  • HIGHCRAFT – HIGHCRAFT is another brand known for maintaining superior craftsmanship. Its inventory includes diverse types of plumbing products like water heater expansion tanks, faucets, pipe hangers, and compression fittings.
  • BackStop – BackStop is a trusted American brand that maintains NSF and IAPMO standards to design every tank. It has diaphragm-type water heater expansion tanks with a 6-year warranty.
  • Zurn – Zurn aims to provide you with the most innovative products. Its product line includes a multitude of items, ranging from backflow preventers to automatic control valves.
  • PROFLO – PROFLO is a US-based plumbing supply company that provides highly engineered products. You can buy different waterworks supplies from this brand.


Should we choose a bigger expansion tank to avoid water pressure effects?

It’s always important to buy a thermal expansion tank of the perfect size. Still, if you have doubts, you can invest in a larger model instead of a smaller one. The larger unit is capable of handling a high volume of hot water and excess pressure.

Can an expansion tank fail?

Yes, an expansion tank can fail. Failure will lead to high water pressure, which will affect the air cushion inside the tank. It means that during every heating cycle, the water volume pressure can result in stress on the pressure relief valve.

Ultimately, you will find a leakage problem. Also, you will notice corrosion, rattling noises, and pipe bursting.

What is the average lifespan of thermal expansion tanks?

The average life expectancy of a water heater expansion tank is eight to 12 years. To make a tank long-lasting, ensure your household water volume pressure corresponds to the expansion tank’s air pressure.

Should I buy more than one thermal expansion tank if I have multiple water heaters?

If you have a single-connected system for multiple heaters, buy multiple thermal expansion tanks for your heating systems. Alternatively, you may purchase a single adequately sized expansion tank for the incoming water pressure.


We’ve provided a brief guide on how to pick the best water heater expansion tank. The small tank is designed to absorb cold water and minimize the excessive pressure caused by a water heater.

While buying the tank, check the material used for constructing it. Also, ensure there’s a proper lining and coating to make the tank rust-resistant.

Choose a thermal expansion tank to prevent damage to your plumbing system. Compare different models of these water heater tanks and make your decision.

With years of experience under his belt, Adam decided to put his water heater knowledge to work. By providing high-quality content and expert guides, Adam hopes to help anyone looking for expert water heater advice.