Model # 141N43

Internet #204296372

Amtrol Therm-X-Trol ST-12 Expansion Tank
0642031395672

Amtrol

Therm-X-Trol ST-12 Expansion Tank

$6715 /each

Product Overview

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 Applications: Residential water heaters, Laundromats, dormitories, office/apartment buildings, restaurants, etc.
store icon Loading Buying Options...
package icon Loading Buying Options...
Sorry, but we ran into issues loading these options. Please try refreshing.

Frequently Bought Together

Product Overview

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 Applications: Residential water heaters, Laundromats, dormitories, office/apartment buildings, restaurants, etc.
  • Eliminates the waste of energy and water, thus saving money
  • Protects the water heater and plumbing fixtures from premature failure
  • 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
  • A professional plumber should check the complete system, including the Therm-X-Trol, yearly and more frequently as the system ages
  • Click here to check out our buying guide on water heaters

Product Overview

Model #: 141N43
Internet #: 204296372

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 Applications: Residential water heaters, Laundromats, dormitories, office/apartment buildings, restaurants, etc.

  • Eliminates the waste of energy and water, thus saving money
  • Protects the water heater and plumbing fixtures from premature failure
  • 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
  • A professional plumber should check the complete system, including the Therm-X-Trol, yearly and more frequently as the system ages
  • Click here to check out our buying guide on water heaters

Info & Guides

You will need Adobe® Acrobat® Reader to view PDF documents. Download a free copy from the Adobe Web site.

Compare Similar

Price
$33.60 /each
$41.85 /each
$67.15 /each
Name 2 gal. Thermal Expansion Tank 2 gal. Air Expansion Tank Therm-X-Trol ST-12 Expansion Tank
Brand Eastman Amtrol Amtrol
Ratings (10) (0) (23)
Product Width (in.) 8 7.5 9
Product Height (in.) 12.5 12.75 15
View Product View Product View Product

Specifications

Dimensions

Product Depth (in.)
11
Product Height (in.)
15
Product Width (in.)
9

Details

Finish
white
Finish Family
White
Product Weight (lb.)
11lb
Returnable
90-Day

Specifications

Dimensions

Product Depth (in.)
11
Product Height (in.)
15
Product Width (in.)
9

Details

Finish
white
Finish Family
White
Product Weight (lb.)
11lb
Returnable
90-Day

Questions & Answers

does it matter if this is installed with the air cap on the top and the screw in fitting on the bottom?

I have one of these that was installed 18 years ago with the air cap on the top and the cold water supply fitting on the bottom. (opposite of the product photo). Im just curious if it matters which orientation it goes.
Asked by: diyguy
It can be installed in any position, preferably in a cold water line on the HOME SIDE of the check valv....
Answered by: Petchu
Date published: 2017-09-05

is this st-12 expansion tank always filled with water, and how would you know if it is bad?

Asked by: Dewey
The rubber diaphragm in the tank separates the air and the water. Excessive water pressure compresses the air. When the line pressure drops the air forces water back into the system. To answer your question, if you get water out when you check the air pressure at the Schrader (air) valve, the diaphragm has failed and the tank needs to be replaced.
Answered by: scotner
Date published: 2017-07-14

Can the ST-12 be mounted horizontally

Asked by: Sid
The manufacture says no but let me explain why because once you understand there reasoning you may choose to do it, as I have, by taking the proper precautions. This unit absorbs pleasure by allowing water to enter it.. This means there is a potential for this tank to completely fill with water. As water is roughly 8 lbs per gallon this means the tank could get pretty heavy. So heavy in fact that it could snap the pipe. So the manufacture recommends to mount them vertically to reduce the stress on the pipe, it has nothing to do with the way it works. There have been times where I have had to cut these tanks in on jobs where a change in water meters caused the customer to experience thermal expansion problems. On some of these jobs there was just no way to fit the tank in vertically. So I have put them in horizontally. in those situations I have take the precaution of adding support to the tank. I have run metal perforated strapping from the ceiling down under the tank and then back up to the ceiling. So essentially making a cradle.
Answered by: BrandAnswers
Date published: 2017-10-12

How many psi max is it?

Asked by: Hao
The st-12 will operate to 150 psi.......
Answered by: Petchu
Date published: 2017-09-05
  • y_2017, m_11, d_22, h_2CST
  • bvseo_bulk, prod_bvqa, vn_bulk_2.0.3
  • cp_1, bvpage1
  • co_hasquestionsanswers, tq_19
  • loc_, sid_204296372, prod, sort_[SortEntry(order=NUM_ANSWERS, direction=DESCENDING), SortEntry(order=SUBMISSION_TIME, direction=DESCENDING), SortEntry(order=LAST_APPROVED_ANSWER_SUBMISSION_TIME, direction=DESCENDING), SortEntry(order=LAST_APPROVED_ANSWER_SUBMISSION_TIME, direction=DESCENDING), SortEntry(order=BEST_ANSWER_FEEDBACK_COUNT, direction=DESCENDING), SortEntry(order=POSITIVE_ANSWER_FEEDBACK_COUNT, direction=DESCENDING), SortEntry(order=NUM_ANSWERS, direction=DESCENDING)]
  • clientName_homedepot
  • bvseo_sdk, java_sdk, bvseo-3.1.1
  • CLOUD, getContent, 100ms
  • QUESTIONS, PRODUCT

Customer Reviews

Therm-X-Trol ST-12 Expansion Tank is rated 4.6 out of 5 by 23.
Rated 4 out of 5 by from 4 Star Review Rating provided by a verified purchaser
Date published: 2017-11-08
Rated 3 out of 5 by from Performs as expected... Performs as expected
Date published: 2017-09-05
Rated 5 out of 5 by from I replaced my old Amtrol expansion tank after 17years. I bought the same model Amtrol and had no... I replaced my old Amtrol expansion tank after 17years. I bought the same model Amtrol and had no problems installing it. It was very easy. I hope this one last as long as my other one did. I also replaced the hot water heater so that everything works well together. Very Happy.
Date published: 2017-02-22
Rated 5 out of 5 by from Product was delivered quickly and is a perfect fit for my water heater. Product was delivered quickly and is a perfect fit for my water heater.
Date published: 2016-12-29
Rated 4 out of 5 by from 4 Star Review Rating provided by a verified purchaser
Date published: 2017-04-04
Rated 5 out of 5 by from Easy install and directions are great! The thermal expansion tank was very easy to install as were the directions to follow. The thermal expansion tank was a replacement for a unit which was worn out. The tank was a near identical replacement for the exixting unit. I would highly recommend this product if you have a hot water heater that has a back flow preventor installed somewhere in line to allow the water to expand. Othewise you may create a situtation where the pipes may burst due to over pressure.
Date published: 2013-12-10
Rated 4 out of 5 by from Larger Tank Required for many installations Any time the house water pressure exceeds 60 psi, and many do, mine was 80 psi past the water softener system, the plumber should install a 5 gallon expansion tank, not a 2 gallon! Most plumbers do no measuring of system pressure, slap a 2 gallon tank up, and do not match the air pressure in tank to system pressure. I am now set at 65 psi after installing gauge and pressure reducing valve and THAT IS BOTH TANK AND SYSTEM PRESSURE! Wonder why your pre-charged 2 gallon tank with only 30 psi from the factory fails after 2 to 3 years? Tank and system pressure have not be matched. PLUMBERS NEED TO GO TO SCHOOL ON THIS ONE!! Hot water tank mfg'rs specify that exceeding 60 psi and above get 5 gallon expansion tank, not 2 gallon. Larger rubber badder can withstand higher air pressure in 60 psi plus systems.
Date published: 2014-02-25
Rated 5 out of 5 by from Works as advertised After installing a solar hot water system that utilizes a 120 gallon tank, I started having elevated water pressure (at times) in the house. I was also getting pipe "hammering," and was afraid I'd end up with a broken pipe. My previous hot water heater was a 50 gallon unit which must have had the same issues, but to a much lesser extent. I never noticed the problem until the larger tank was installed. The Amtrol thermal expansion tank seems to have solved the problems. It's been in for about two weeks now, and haven't had a single high pressure episode, or any pipe hammering since. The unit appears to be of very high quality, and I had no problems installing it...very simple. I ended up making my own mounting bracket for the unit. There are commercially available brackets made, but the Home Depot did not carry them, or offer them on their website. To save the cost + shipping from the other suppliers, I built a simple unit out of plywood, and a couple of large hose clamps.
Date published: 2014-01-11
  • y_2017, m_11, d_22, h_2
  • bvseo_bulk, prod_bvrr, vn_bulk_2.0.3
  • cp_1, bvpage1
  • co_hasreviews, tv_0, tr_23
  • loc_, sid_204296372, prod, sort_[SortEntry(order=RELEVANCE, direction=DESCENDING)]
  • clientName_homedepot
  • bvseo_sdk, java_sdk, bvseo-3.1.1
  • CLOUD, getContent, 103ms
  • REVIEWS, PRODUCT