Top 10 Best expansion tank in 2026

Last Updated - 6/23/2026

🏆Best Choice

EVIL ENERGY

EVIL ENERGY Coolant Overflow Tank, Aluminum Radiator Tank, Reservoir Expansion Tank Universal 1L Black

9.8

ChoiceComparer.com Score

9.8

/ 10

Outstanding

Main highlights

•[Size] The Male to barb fitting thread size is M14*1.5.can work with 3/8" ID fuel hose.Overflow tank storage volume1L.
•[Fitment]Universal coolant reservoir tank, fit for mostly of vehicles.Please measure before purchase to make sure there is enough space for installation.
•[Note]Tight closed cap, fully TIG welded and thread come with O-ring gasket, let coolant reservoir can keep a good closed environment and prevent coolant leakage.It is high recommended use Tetflon tape when install, it can enhance airtightness prevent interface leakage.
•[Function]When the coolant pressure in the radiator exceeds the pressure cap setting, the coolant is sealed through the pressure cap and flows through the overflow tube into the radiator coolant overflow tank.Bottom port is radiator overflow,the top port is the tank overflow.
•[Installation] Barb fittings and bottom drain plugs are supplied with O-rings to ensure a good seal and Teflon tape is recommended for installation.

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$31.99

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Eastman

Eastman 3/4 Inch Brass Swivel Expansion Tank Tee, Fits 2-10 Gallon Tanks, 26090Z

9.7

ChoiceComparer.com Score

9.7

/ 10

Outstanding

Main highlights

•EASTMAN EXPANSION TANK TEE: The 3/4 Eastman pressure tank tee offers a swivel design that allows for both vertical and horizontal tank orientation, providing flexibility and ease for any installation setup
•DESIGN: This expansion tank tee is designed to minimize potential leak points and is crafted from lead-free brass, ensuring a durable and reliable connection in your water system
•COMPATIBILITY: Suitable for a range of tank sizes from 2 to 10 gallons, this expansion tank tee is ideal for both domestic and commercial water systems. NSF/ANSI/CAN 61, NSF/ANSI/CAN 372
•DURABLE: This swivel expansion tank tee is built to withstand pressure up to 200 PSI, featuring an EPDM gasket for a secure seal that maintains performance under demanding conditions

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$20.39

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A-Premium

A-Premium Engine Coolant Overflow Recovery Reservoir Tank - W/Sensor & Cap [DOHC, 6Cyl 2.2 2.5 2.8 3.0L] Compatible with BMW E46-99-06-320i, 325xi, 328i, 330xi, X3, X5 & More, for# 17137787039

9.5

ChoiceComparer.com Score

9.5

/ 10

Outstanding

Main highlights

•[Vehicle Fitment]: ①Compatible with BMW (E46 Sseries) 320i 2001-2005 2.2L, 323Ci 2000 2.5L, 323i 1999-2000 2.5L, 325Ci 2001-2006 2.5L, 325i 325xi 2001-2005 2.5L, 328Ci 2000 2.8L, 328i 1999-2000 2.8L, 330Ci 2001-2006 3.0L, 330i 330xi 2001-2005 3.0L; ②fits BMW (E83 E53 Series) X3 2004-2010 2.5L/3.0L, X5 2001-2006 3.0L
•[Reference Number]: 603-535, 17137787039, 17111436413, 17117573781, 17132247553,EPK0018, EPT0018, FRT1901C, S49002
•[Specifications]: ①Pressurized: Yes ②(Cap)Maximum Pressure Rating: 30 PSI ③(Cap)Type: Spring Loaded Twist ④Materials: (PA)Plastic ⑤Mounting Hole Quantity: 1 ⑥Product Contents: [1] Cap & [1] Sensor & [1] Clamp; ⑦Height: 359.7 mm; ⑧Length: 121.3 mm; ⑨Width: 133.4 mm
•[Functions]: Using stable and outstanding (PA) plastic materials can withstand excessive heat and vibration. Helping to reduce oil dilution, cylinder bore wear, fuel consumption, exhaust emission, and improving efficiency of the heating system.
•[Customer Support]: 1 Year Unlimited-mileage Quality Guarantee; With brand-new and being sturdy and, this Coolant Reservoir is the ideal replacement. We extremely value your satisfaction and strive to provide you good shopping experience.

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$32.99

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Amtrol

AMTROL 102-1#30 EX-30 30 Extrol Expansion Tank

9.4

ChoiceComparer.com Score

9.4

/ 10

Excellent

Main highlights

•InLine well tank
•Watertight reservoir for expanded water
•Thick, heavy duty Butyl/EPDM diaphragm for long service life
•Sealed air cushion - factory pre-charged and 100% tested
•Strong, deep-drawn steel tank

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$61.00

$65.00

-6%

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Eastman

Eastman 2-Gallon Mini Thermal Expansion Tank, Stainless Steel Hammer Arrestor with 1/2 Inch Threaded Connection, 60008

9.2

ChoiceComparer.com Score

9.2

/ 10

Excellent

Main highlights

•EASTMAN THERMAL EXPANSION TANK: The Eastman Mini Thermal Expansion Tank is designed to absorb potential increases in pressure within the water heater, safeguarding your tankless water heaters from thermal expansion and preventing leaks and repairs
•DURABLE: Crafted with durable 304 stainless steel, this expansion tank ensures longevity and is suitable for both indoor and outdoor installation, providing a reliable solution for your water heating system
•VERSATILE: With its 1/2-inch MIP threaded connection, this thermal expansion tank offers flexible installation options and can be mounted in any orientation; features adjustable pressure making it a convenient addition to your plumbing system
•CAPACITY: The mini thermal hammer arrestor is ideal for tankless or point-of-use water heaters with a storage capacity of 2 gallons or less. Max pressure 150 psi; Max temperature 210 F
•EASY TO INSTALL: This expansion tank is designed for quick and easy installation, ensuring that your water heater is protected without the need for professional assistance

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$18.75

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Eastman

Eastman Thermal Expansion Tank, 2 gal, 3/4 in MIP Connection, 60022

9.1

ChoiceComparer.com Score

9.1

/ 10

Excellent

Main highlights

•WATER HEATER PROTECTION: Prevents excess pressure caused by thermal expansion in water heater systems
•DURABLE CONSTRUCTION: Built with a butyl rubber diaphragm and 304 stainless steel system connection
•PRE-CHARGED: Factory pre-charged at 40 PSI for reliable performance and ease of installation
•SPECS: 2 gallon capacity; rated up to 150 PSI and 210 degrees F; 3/4 in MIP connection
•WARRANTY: Backed by a 6-year limited warranty for added reliability

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$43.48

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ZhouDaShu

ZhouDaShu Expansion Tank Mounting Bracket for Hot Water Heater,Thermal Expansion Tank Holder with 2 Earthquake Straps,Support 5-Gallon Hot Water Tanks up to 13 inches in Diameter-1 Set

8.9

ChoiceComparer.com Score

8.9

/ 10

Great

Main highlights

•Expansion Tank Mounting Bracket:Using this expansion tank bracket you can install the expansion tank to the water heater unit. The expansion tank for hot water heater is able to securely mount the tank directly where you want to place the tank, and the hot water expansion tank bracket makes the water heater safer to use
•Quality Material: The mounting bracket for water heater expansion tanks is made of heavy metal with 2 stainless steel earthquake straps. The water tank bracket is durable, not easy to deform, waterproof, rustproof, anti-corrosion and reusable
•Simple Installation: The expansion tank holder is easy to install, first mount the water heater expansion tank bracket on the wall, then pass the 2 earthquake straps through the mounting holes while adjusting the earthquake straps, lock the position with a quick switch, and then fix the water heater tank on the bracket. It is recommended to place a stopper on the expansion tank mount bracket close to the tank to protect the edges of the tank mounting bracket from touching the tank
•Multi-purpose use: The expansion tank support bracket is suitable for water heater thermal expansion tanks, nitrogen tanks, propane tanks and other cylindrical drums up to 5 gallons or 13 inches in diameter, in order to meet the use of large-diameter water heater tanks, we provide longer straps, so you will need to cut off a part of it yourself when hanging a smaller diameter tank
•Tip: Please make sure your tank is the right size before purchasing the thermal expansion tank mounting bracket. Be sure to wear good gloves when using the hot water heater expansion tank bracket and stainless steel straps to avoid being cut by sharp-edged metal parts

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$15.99

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oiununo

Potable Thermal Expansion Tank 2.1 Gallon, 3/4" MNPT Connection, Compact Design for Water Heater, RV, Marine, Boat, Off-Grid Systems, Residential Plumbing & Solar Thermal (2.1 Gallon)

8.8

ChoiceComparer.com Score

8.8

/ 10

Great

Main highlights

•[Dual O-Ring Seal Leak-Proof Air Valve]: Our expansion tank features leak-proof air valve with double O-ring seals to prevent pressure loss and leakage in thermal expansion systems.
•[Thick-walled & Withstands High Pressure]: This water expansion tank feature thick-walled carbon steel construction with factory test pressure rating of 207 PSI. Withstands water hammer impact and cyclic pressure fluctuations (e.g., pump start/stop cycles), preventing tank bursting. While factory-tested to 207 PSI, our expansion tanks require operating pressures ≤150 PSI for sustained safety and service life.
•[Food-grade Materials]: The thermal expansion tank features a 3/4" MNPT connection constructed of food-grade type 304 stainless steel. Also, The expansion tank diaphragm is fabricated from food-grade EPDM rubber(C resistance ( -40~302℉ stability), ensuring compatibility with potable water systems.
•[Enjoy Steady Water Flow]: Our expansion tank will control pressure increases caused by thermal expansion to a level below the water heater relief valve setting, that prevent relief valve discharge and water hammer in piping systems. Also, extends service life of piping and water heater. In hydronic heating systems, expansion tanks can reduce pump runtime by 30% and minimize unnecessary cycling, achieving 15-25% energy savings.
•[For Various Water System Applications]: This expansion tank is ideal for modern, high efficiency systems including well water systems, hot water systems, solar thermal systems, marine, RV water systems and other pressurized water applications.

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$59.99

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Watts

Watts ETX-30 Non-Potable Water Carbon Steel Expansion Tank for Closed Loop Hydronic Heating System Piping, 1/2" MNPT Connection, Tank Volume 4.7 Gallons, Maximum Pressure 75 psi

8.6

ChoiceComparer.com Score

8.6

/ 10

Good

Main highlights

•WATER EXPANSION TANK: With a generous 4.5 tank gallon volume, the Watts Non-Potable Water Expansion Tank is designed for use in commercial and residential closed loop hydronic heating system piping to control the thermal expansion of hot water and maintain system pressure below the relief setting of the relief valve.
•DURABLE CONSTRUCTION: This tank is constructed from high-quality carbon steel with an epoxy finish, ensuring long-lasting performance. It is also equipped with a durable expansion membrane that minimizes the loss of the air charge.
•VERSATILE MOUNTING: This tank is designed for easy installation, mounting directly to the supply piping. It features a 1/2" MNPT system connection and a 0.302-32" charging valve connection (standard tire valve) to facilitate on-site charging.
•HIGH PRESSURE CAPACITY: Pre-charged at 12 psi, this expansion tank is built to withstand the demands of hydronic heating systems, boasting a maximum pressure rating of 60 psi. It works in tandem with hot water heaters to absorb increased water volume, preventing system overpressure and ensuring the longevity and efficiency of the heating system.
•EVERY DROP COUNTS: Water. It's in our name and close to our hearts. Since 1874, Watts Water Technologies has been delivering innovative technologies that make the world's most precious resource safe and accessible. Everything we design is made to keep the Earth's most precious resource safer, cleaner, and more useful for our customers. Our family of brands offers one of the most varied product lines in the world, with world-class, water-related solutions.

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$72.89

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Flexcon Industries

Flexcon Industries PH5 FLEX2PRO Thermal Expansion Tank - 2.1 Gallon

8.5

ChoiceComparer.com Score

8.5

/ 10

Good

Main highlights

•PH tanks feature a 100% butyl diaphragm and plastic liner to separate the system water from the tank’s air precharge
•The system connection has a stainless steel nipple to prevent corrosion, something so other manufacturer offers
•Tanks are finished with appliance quality paint which helps prevent external corrosion
•Volume: 2.1 Gallons

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$47.98

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