10 Best Water Heater Expansion Tanks
There are many reasons to get a water heater expansion tank, but the most important and common reason people use them is to help reduce water pressure in the home (which can cause a range of issues).
When water is heated in a traditional water heater, it expands, increasing the pressure within the water heater tank. This is referred to as thermal expansion and it can cause problems in your plumbing system.
With a water heater expansion tank, you can reduce the amount of pressure, increasing the life of your appliances and plumbing.
Why You Might Need a Water Heater Expansion Tank
Some people have what is called an open water system. In this type of system, excessive pressure is pushed back into the city water system, reducing the amount of strain this pressure may put on a home’s plumbing.
However, closed water systems are a lot more common. In closed water systems, water isn’t pushed back into the larger city water system.
With a water heater expansion tank, the extra volume of water, caused by expansion during the heating process, has a place to go.
In essence, this is a backup system for homes with high water pressure as a means to help reduce the stress and pressure put on your plumbing and appliances.
10 Best Water Heater Expansion Tanks
We scoured the internet to select our picks for the best water heater expansion tanks available on the market.
We narrowed down the myriad of options to our top 10 choices. All the models we review here are high-quality, highly-rated, and designed to provide enhanced pressure relief to help extend the life of your water heater and plumbing system.
As an Amazon Associate we earn from qualifying purchases.
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
1. Amtrol ST-12 Thermal Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
Amtrol is a trusted and reputable maker of a range of water heater expansion tanks, accessories, and other products. Their ST-12 Thermal Expansion Tank is an affordable, high-quality expansion tank and is our top choice for the best water heater expansion tank available on the market.
The tank is easy to install and is suitable for use with most standard-sized water heaters. The expansion tank will help reduce the amount of water and energy waste often inherent with traditional water heaters.
The tank will reduce the amount of pressure in hot water heater tanks and the rest of the plumbing system, which will help to extend the life of your plumbing, fixtures, and appliances.
Additionally, the expansion tank will reduce the amount of pressure build-up that can often occur in various places throughout your plumbing system that can cause a wide range of issues.
It is a 4.4-gallon expansion tank that meets modern plumbing codes and will enhance backflow prevention.
It can increase the amount of usable hot water by returning held water to the overall system when the main tank gets low. Not only does this reduce wasted water and energy, but it can also allow you to get more hot water out of your system than you would be able to without the expansion tank.
Specifications:
- 4.4 gallons
- 2.2 pounds
Key Features:
- Suitable for use with most standard-sized hot water heaters
- Easy to install
- Reduces the amount of pressure in the plumbing system
- Reduce water and energy waste
- Reduce pressure build-up
- Meets modern plumbing codes
2. Falcon Stainless EXPT-2 Thermal Potable Water Heater Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
Falcon Stainless is a trusted and well-known maker of a range of home plumbing and water heater supplies, accessories, and expansion tanks. Their EXPT-2 water heater expansion tank is a high-quality, well-made water heater expansion tank that won’t break the bank in the process.
The tank is made from 16 gauge stainless steel and finished with urethane paint, which reduces corrosion and chipping, which can reduce the life of an expansion tank. The tank is suitable for use with standard-sized water heaters with up to a 50-gallon tank.
This is a diaphragm-style system that features a butyl bladder and polypropylene liner for better operation and a longer lifespan for the expansion tank. The unit has a steel clench ring for regular movement and prevents the bladder from pressing against the tank wall when it is full.
This tank is 100% pressure tested for enhanced safety and functionality. It is easy to install and operate and has a long lifespan. It comes with a 5-year limited warranty for added peace of mind with your purchase.
Specifications:
- 2.1 gallon
- 4.9 pounds
Key Features:
- Suitable for use with hot water heaters up to 50-gallons
- Diaphragm-style system
- Made with 16 gauge steel to reduce corrosion
- Steel clench ring keeps bladder in place
- 100% pressure tested
- Easy to install
- 5-year limited warranty
3. Watts 4.5-gallon Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
Watts is a well-known and highly reputable company that is best known for making a wide range of plumbing-related appliances and accessories. Their product line ranges from pipe fittings and check valves to water heater expansion tanks.
Their 4.5-gallon expansion tank is very well-made, versatile, long-lasting, and affordable. It is large in capacity and works well with water heaters with tanks of up to 50-gallons. It can be used with any type of direct-fired water heater, which includes most traditional systems.
The tank will control the amount of thermal expansion in your hot water system, reducing the amount of pressure that builds up within the hot water heater tank and other parts of plumbing. The system uses a diaphragm made from butyl, for long-lasting use.
The tank also has a durable membrane that separates the excess water from the air cushion that is a huge part of the tank.
The system is designed to keep water pressure below 80 psi, above which, damage to plumbing and fixtures can occur and the life of the plumbing shortened. The tank is easy to install and can also help reduce the amount of water and energy wasted by water heaters alone.
Specifications:
- 4.5 gallons
- 8.78 pounds
Key Features:
- Suitable for use with water heaters up to 50-gallons
- Long-lasting
- Controls thermal expansion automatically
- Diaphragm system
- Easy to install
- Reduce energy and water waste
4. Amtrol ST-5 Thermal Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
Amtrol is such a well-known and respected brand that we have numerous options from this brand on this list. Their ST-5 is an excellent option for people who live in smaller homes or have a hot water heater that is less than 50-gallons.
The tank uses a bladder style expansion vessel and is made from high-quality stainless steel to reduce corrosion. The system is made in the USA from the finest materials and will stand the test of time.
The tank will return water to the hot water system when using hot water or when the main tank gets low. The unit will prevent the relief valve from going off, causing further issues. The tank is easy to install and can be installed horizontally or vertically.
This tank is lightweight and easily reduces built-up pressure and will help to eliminate water and energy waste as well. It comes with a 5-year limited warranty for added peace of mind for your purchase.
Specifications:
- 2 gallons
- 4.6 pounds
Key Features:
- Suitable for smaller homes and water heaters up to 50-gallons
- Made from stainless steel to reduce corrosion
- Made in USA
- Returns hot water to the system when needed
- Easy to install
- Can be installed horizontally or vertically
- Reduces water and energy waste
- 5-year limited warranty
5. Amtrol 7.4-gallon Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
We now review one more option from Amtrol as we go through our choices for the best water heater expansion tank.
Their 7.4-gallon expansion tank is an affordable, high-quality option for people with larger homes who need an expansion for a hot water heater that is larger than 50-gallons.
This is a diaphragm system that helps to reduce energy and water waste while also reducing built-up pressure that can result in closed systems. The unit is well-built from the finest materials to help reduce the potential of corrosion, also increasing the lifespan of your plumbing and fixtures.
The tank is made in the United States and made in an ISO-registered facility that supports American workers and sticks to a high standard of manufacturing.
The unit is easy to install and also comes with a 5-year limited warranty to give you more confidence in your purchase.
Specifications:
- 7.4 gallons
- 4 pounds
Key Features:
- Suitable for use with water heaters over 50-gallons
- Diaphragm system
- Made from corrosion-resistant materials
- Made in the USA
- Easy to install
- 5-year limited warranty
6. Falcon Stainless EXPT-4 Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
Falcon is a trusted, reputable, and high-rated manufacturer of quality water heater expansion tanks. This EXPT-4 model is a high-capacity expansion tank that is well suited for homes with large water heaters up to 120-gallons.
The tank is made from 16 gauge solid stainless steel and painted with urethane paint to help reduce the risk of corrosion which reduces the life of your expansion tank and the surrounding system.
The unit is a diaphragm system that is 100% pressure tested and is highly effective at reducing the amount of pressure in your system. It helps reduce the amount of water and energy wasted in your hot water system.
The tank also has a steel clench ring that makes sure the diaphragm doesn’t press up against the walls of the tank. This helps enhance the life of your expansion tank.
The tank comes with a 5-year limited warranty to give you enhanced peace of mind in your purchase.
Specifications:
- 2.8-gallon tank
- 9 pounds
Key Features:
- Suitable for use with larger water heaters of up to 120-gallons
- Made from 16 gauge stainless steel to reduce corrosion
- Diaphragm style
- Reduces water and energy waste
- 100% pressure tested
- 5-year limited warranty
7. Highcraft 2.1-gallon Hydronic Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
Highcraft is a well-known and trusted maker of a range of plumbing appliances and accessories. Their product line ranges from kitchen faucets and tank supply lines, to water heater expansion tanks.
This tank is well suited for use with standard-sized hot water heaters less than 50-gallons. It is well-made from carbon steel to reduce the likelihood of erosion.
The unit is a diaphragm style made from SBR rubber with a polypropylene liner for enhanced lifespan. The tanks reduce pressure build-up and will return hot water to the system when needed. The unit is a low profile tank that is easy to install and stands the test of time.
The tank is factory leak tested and NSF61 Certified for added peace of mind.
Specifications:
- 2.1 gallons
- 4.6 pounds
Key Features:
- Suitable for use with tanks up to 50-gallons
- Made from carbon steel for reduced chance of erosion
- Diaphragm style
- Low profile tank
- Factory leak tested
- NSF61 certified
8. Eastman 4.5-gallon Thermal Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
Eastman is a reputable and highly-trusted, well-rated company that makes a wide range of plumbing-related appliances and accessories. Their product line ranges from water heaters, drain accessories and valves, to water heater expansion tanks.
This tank is well suited for use with standard-sized water heaters up to 50-gallons. The tank helps to prevent pressure build-up as well as preventing hot water from back flowing into cold water intakes and lines.
The thermal expansion tank is well-made and comes pre-charged at 40 psi but can be adjusted to meet the specific needs of your plumbing system. The unit is a diaphragm style system made from butyl rubber for enhanced lifespan.
The unit also features stainless steel fittings and is made from materials that are corrosion-resistant. The tank is equipped with a standard 3/4-inch male iron pipe connection and comes backed by a 6-year limited warranty.
Specifications:
- 4.5 gallons
Key Features:
- Suitable for use with water heaters up to 50-gallons
- Prevents pressure build-up and prevents hot water backflow
- Comes pre-charged at 40 psi but can be adjusted
- Diaphragm style
- Diaphragm made from butyl rubber
- Stainless steel, corrosion-resistant fittings
- 6-year limited warranty
9. Flexcon 4.8-gallon Thermal Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
Flexcon Industries is a well-known and trusted manufacturer that is best known for making water heater expansion tanks and related accessories. Their 4.8-gallon tank is well suited for water heaters up to 50-gallons.
This tank is a diaphragm style system made from butyl rubber with a plastic liner that separates the diaphragm and water from the air cushion in the expansion tank.
This tank is made from the highest quality material and is finished with corrosion-resistant paint for enhanced lifespan. The system will reduce the amount of pressure build-up and reduce the waste of hot water and energy in the process.
The tank comes with a 1-year limited warranty for more peace of mind in your purchase.
Specifications:
- 4.8-gallons
- 8.75 pounds
Key Features:
- Suitable for use with up to a 50-gallon water heater
- Diaphragm style system
- Diaphragm made from butyl rubber and a plastic liner
- Painted with corrosion-resistant paint
- Reduce hot water and energy use
- Easy to install
- 1-year limited warranty
10. Water Worker 2-gallon G5L Expansion Tank
Last update on 2024-04-18 at 12:20 / Affiliate links / Images from Amazon Product Advertising API
Water Worker is an up and coming brand that is known for making high-quality plumbing solutions and accessories. Their product line ranges from pre-charged well tanks and plumbing accessories, to water heater expansion tanks.
Their 2-gallon G5L Expansion Tank is a high-quality, well-made expansion tank that is suitable for use with water heaters up to 50-gallons.
The tank is made to the highest standards and meets all the requirements of the National Sanitation Foundation (NSF) under ANSI/NSF STD 62 guidelines. This means their products are made with the best materials and to the highest standards.
This is a diaphragm style tank with seamless construction so it flexes rather than stretches. Both the diaphragm and the interior liner separates water and air and is built for added strength.
The unit features a high-gloss enamel finish that reduces the risk of corrosion. The tank comes pre-charged at 25 psi, but it can be adjusted to meet the specific needs of your home.
The tank is easy to install and backed by a 5-year limited warranty so you can have greater confidence in your purchase.
Specifications:
- 2-gallons
- 4.99 pounds
Key Features:
- Suitable for use with water heaters up to 50-gallons
- Meets ANSI/NSF STD 62 guidelines
- Diaphragm system
- Seamless diaphragm design so it flexes instead of stretching
- Corrosion-resistant paint finish
- Pre Charged to 25 psi but can be adjusted
- 5-year limited warranty
Water Heater Expansion Tank Buying Guide
When choosing the best water heater expansion tank to meet your needs, there are a couple of things you will need to take into consideration. The most important factors to consider are cost, size, and the type of expansion vessel used.
Water Heater Expansion Tank Cost
You can get a high-quality, well-made water heater expansion tank for less than $150.
In fact, most water heater expansion tanks cost between $40 and $60. But don’t just buy the cheapest one. Make sure to get one that’s compatible with your water heater!
What Size Water Heater Expansion Tank Do You Need?
You want to make sure that the hot water expansion tank you get is up to the job you want it to do.
In order to know what size expansion tank you need, you will first need to know how large of a hot water heater tank you currently have. There are many places online that will show you what size expansion tank you need given the water heater you have. Here’s a good place to start.
A rule of thumb is that it is better to get too large of an expansion tank than too small of one. When in doubt, buy larger than you think you need and you’ll be ensured that it will serve the job you need it to.
Types of Expansion Vessels
There are three expansion vessel types that are used with water heater expansion tanks. These include compression type, bladder type, and diaphragm type.
Compression types are also called plain steel and do not have a bladder. It is the oldest style of water heater expansion tank. There is an air cushion above the water in the tank and it will need to be controlled for the heater to operate optimally.
Bladder type expansion tanks use a bladder that separates the water from the air cushion. The bladder will expand and contract based on how much water is in the expansion tank.
Diaphragm type is an expansion tank that has two sections that are separated by a rubber diaphragm. Water is stored in the diaphragm and it will expand and contract as needed.
Each type of expansion vessel has its pros and cons and what will work best for you will depend on the type of water heater you currently have, your budget, the amount of extra pressure in your water system, and more.
Here’s a very helpful video explaining each vessel type:
Frequently Asked Questions
Do I need a water heater expansion tank?
There are many reasons that people use water heater expansion tanks. One of the most common reasons that people get expansion tanks is when they have issues with water pressure.
Sometimes, water heater systems have check valves for regulating pressure. An excessive amount of pressure can cause issues with plumbing, including reducing the life of your plumbing.
Expansion tanks can be used to reduce the amount of pressure in the plumbing system and in some places, are even required.
How long do water heater expansion tanks last?
It really depends. If you choose the properly sized tank to match your water heater, expansion tanks typically last between 5-10 years.
If you use an expansion tank that isn’t large enough for the job, or you fail to properly maintain it, it isn’t going to last as long.
Given how affordable they are, and how expensive water heaters are, it makes sense to use and replace these systems when needed.
