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Amtrol ST-12 Thermal Expansion Tank

by Amtrol
In stock
Original price $68.79 - Original price $68.79
Original price
$68.79 - $68.79
Current price $68.79
Size: 4.4 Gallons

Nothing is more reliable than the Amtrol ST-12 Thermal Expansion Tank. This essential is built with high-strength steel and heavy-duty butyl and keeps your home water pressure in check by absorbing expanded water in closed hot water systems.

Key Features: 

  • Antimicrobial liner neutralizes bacteria on contact
  • Patented Turbulator water circulation device
  • Strongest tank design featuring deep-drawn steel and multi-dome construction
  • Heavy-duty butyl forms a thick diaphragm
  • Projection welded air stem to reduce leaks


Shell: High-strength steel
Diaphragm: Heavy-duty butyl NSF/ANSI 61
Liner: Antimicrobial
Air Valve: Projection welded
Air Valve Cap: Patented InSight Indicator Cap
Factory Precharge: 50 PSIG for in-line models, 40 PSIG for stand models
Max. Operating Temperature: 200º F (93º C)
Max. Operating Temperature for ST-1: 140º F (60º C)
Max. Working Pressure: 150 PSIG (10.3 bar)
Warranty: ST-1 through ST-12: 7-Year Limited, ST-25V through ST-210V: 1-Year Limited

Benefits and Advantages: 

The Amtrol Thermal Expansion Tank is designed to prevent excessive water and reduce damage to valves and plumbing fixtures at home.

Usage or Application: 

Applications include closed, potable hot water systems to control pressure build-up and protect the water heater. It also accepts expanded water as a system temperature rises and returns hot water when demand occurs.

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70 Years of Business

Family-owned and operated

Amtrol: The Name You Can Trust

Innovation, quality, and service—these are the building blocks that have supported Amtrol’s continued success since 1946. This titan of the industry has consistently produced revolutionary products, including the EXTROL and pre-pressurized well tanks. 

Amtrol tanks are beloved for their unparalleled designs and functionality, making them the top choice for commercial and home water tank needs. Enjoy Amtrol’s many efficient and high-performing features when you shop at NYDirect!

What Sets Amtrol Apart

Amtrol pioneered the manufacturing of expansion and pressure tanks. They stand above the competition by providing the following:

Product Innovation

For Amtrol, creating intuitive and incomparable product inventions is the name of the game. They continue to make significant waves in the hydronics industry with their ever-evolving Amtrol pre-pressurized tanks for both home and commercial use!

Quality You Won't Find Elsewhere

Water leaks, bacteria buildup, and other failures have nothing on Amtrol. Their products are built to last using high-quality materials, meaning they’ll persevere through even the toughest challenges. Amtrol is the name you know for a reason!

Pros in Handling Pressure

Amtrol has continued to thrive thanks to its unmatched customer service; it leaves clients happy after every interaction. You’re in good hands knowing their products are backed by an industry-leading seven-year warranty.

Types of Amtrol Products We Sell

At NYDirect, we offer a plethora of Amtrol tanks and products for your home or business:

  • Amtrol Expansion Tanks - These heavy-duty devices absorb expanded water within closed hot water systems to keep pressure in check. 
  • Amtrol Well Pressure Tanks - Solve all home water pressure problems with 150 PSIG of working pressure and an innovative hook ring and groove design.
  • Amtrol Water Pressure Booster System - Increase the inbound city water pressure by up to 50 PSIG in single and multi-family homes. 
  • Amtrol Smart Control - Get more control over your Amtrol water heaters with this intelligent device that eliminates post-outage resets.

Tips for Maintaining Your Amtrol Products

Amtrol products are efficient in delivering pressurized water and controlling heat expansion. However, like anything, they can suffer from wear and tear from frequent use. Make your Amtrol products last even longer with these maintenance tips:

  • Always read the product manual for the Amtrol pressure and expansion tanks before installing, repairing, or tinkering with them. 
  • Schedule yearly inspections with a licensed professional to check the tank’s precharge (and more frequently as your device gets older).
  • When checking the precharge of Amtrol expansion tanks, always start by isolating them and removing all water inside. 
  • Monitor the cap of your Amtrol tanks for discoloration, then contact a plumbing professional plumber if you notice it.

Why Shop Amtrol With Us

Trust NYDirect to deliver industry-standard Amtrol tanks and related products. We ensure you only get the best service you deserve:

Wide Selection

Our expansive online catalog has everything you need for commercial and home improvement. Enjoy the many unique features of Amtrol products!

Shipped Directly to You

We ship to you quickly and affordably. You won't have to worry about product damage because all items are packed carefully. Expect your order to arrive in mint condition!

Family Owned and Operated

NYDirect is a family-run business. We understand the issues experienced by homeowners and business contractors; we want to be part of the solution. Our professional team puts your best interests first to meet and exceed your expectations.

Get the Best Amtrol Products Today From NYDirect

Amtrol pressure and expansion tanks are the best for regulating water pressure in homes and commercial buildings. No other brand can match their performance, meaning Amtrol should be your first for these kinds of devices. 

At NYDirect, we believe you deserve quality products and services. Shop our Amtrol catalog today to find what you’re looking for—and expect whatever you order to arrive directly to your doorstep in perfect condition. It’s our family’s promise to yours. 

Do you have any questions about Amtrol tanks? Send us a message

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Amtrol ST-12 Thermal Expansion Tank