Therm-X-Trol ST-12 Thermal Expansion Tank (4.4 Gal Volume)


Brand: Amtrol

Mfr Part#: 141N43

Model: ST-12

UPC#: 642031395672

Availability: In Stock
Usually ships: within 1 business day
Qty Price
$54.95 / each
x4 $211.80 / box & Free Shipping
(4 x $52.95 / each)
  • Description
  • Literature
  • Reviews (2)
  • FAQs (2)

Amtrol ST-12 (Therm-X-Trol) is a water heater expansion tank, designed for use in domestic hot water heating systems to eliminate the potential hazards of water expansion.
Water heater expansion tank is commonly installed in a domestic hot water system that contains a backflow preventer, a check valve or a pressure reducing valve.

Amtrol ST-12 Advantages:
Eliminates the waste of energy and water, thus saving money;
Protects the water heater and plumbing fixtures from premature failure;
Reduces potential safety hazards associated with thermal expansion;
Prevents a dangerous pressure build-up in the system;
Prevents the relief valve from going off;
Therm-X-Trol brand is the #1 choice of Professional Installers;

Standards & Approvals:
NSF/ANSI 61®, IAPMO, SBCCI & City of Los Angeles listings.

Amtrol ST-12 Applications:
Residential water heaters, laundromats, dormitories, office/apartment buildings, restaurants, etc.

Technical Specifications:

  • Factory pre-charged 40 psig;
  • System connection: 3/4" male threaded;
  • Stainless steel system connection;
  • Max. operating temperature: 200F;
  • Max. operating pressure: 150 psi;
  • Expansion tank volume: 4.4 gallons;
  • Max. acceptance factor: 0.73;
  • Height: 15";
  • Diameter: 11";
  • Shipping weight: 9 lbs.


5-year manufacturer's warranty.
Therm-X-Trol ST-12 Thermal Expansion Tank (4.4 Gal Volume) has an average 5.0 out of 5 rating based on 2 user reviews.
This product came up to my expectations/
By Alex (from Twp. of Washington, NJ) on 11/28/2011
"The order was delivered extremely quickly 2 days after the order was placed. My plumber installed the tank in 5 minutes. The old tank was full of water. I was extremely satisfied !"
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reliable product
By mary (from pa) on 8/23/2011
great quality. and they have the best price
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Can this tank be mounted with the water line connection at the bottom rather than at the top?
Read 1 answer
Amtrol's manual does not have any restrictions concerning the mounting the tank under or over the line. The main condition is that it must be vertical in order to avoid stress on the connection point. So the answer is yes, as long as you level the expansion tank properly.
Answered on 8/31/2015 by PexUniverse Customer Service
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can it be mounted horizontalygs6bk
Read 1 answer
Amtrol allows only for vertical installation of this expansion tank.
Answered on 7/11/2012 by PexUniverse Customer Service
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