---
product_id: 8847368
title: "ST-12 Thermal Expansion Tank"
brand: "amtrol"
price: "฿12431"
currency: THB
in_stock: true
url: https://www.desertcart.co.th/products/8847368-st-12-thermal-expansion-tank
store_origin: TH
region: Thailand
---

# Energy-efficient design Water-saving tech Safety pressure control ST-12 Thermal Expansion Tank

**Brand:** amtrol
**Price:** ฿12431
**Availability:** ✅ In Stock

## Summary

> 💡 Smart Solutions for Modern Living!

## Quick Answers

- **What is this?** ST-12 Thermal Expansion Tank by amtrol
- **How much does it cost?** ฿12431 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.co.th](https://www.desertcart.co.th/products/8847368-st-12-thermal-expansion-tank)

## Best For

- amtrol enthusiasts

## Why This Product

- Trusted amtrol brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Safety First:** Avoids dangerous pressure build-up in your plumbing.
- • **Reliable Performance:** Manufactured by AMTROL, a trusted name in home solutions.
- • **Lightweight & Compact:** Easily fits into your existing setup without hassle.
- • **Save Money, Save Water:** Eliminates waste, maximizing your resources.
- • **Protect Your Investment:** Prevents premature failure of your water heater.

## Overview

The AmtrolST-12 Thermal Expansion Tank is designed to enhance the efficiency of your plumbing system by preventing pressure build-up, saving water and energy, and protecting your water heater from premature failure. Weighing just 2.2 pounds and measuring 8 x 11 x 15 inches, this compact tank is a must-have for any eco-conscious homeowner.

## Description

Amtrol ST-12 THERM-X-TROL Expansion Tank, 4.4 Gallon (141N43) What Is Thermal Expansion? With modern plumbing codes mandating backflow prevention, thermal expansion can cause pressure buildup in domestic water systems. When demand is put upon a potable water system, hot water is drawn from the water heater. Cold water from the supply line enters the water heater to replenish it. The colder water is heated to replace the hot water used. With the installation of a backflow preventer, check valve or pressure reducing valve on the supply line, the water heater and the system piping form a closed plumbing system under pressure. As the water is heated, thermal expansion occurs. Pressure increases until the relief valve opens and the expanded water "spills" from the water heater. This "spillage" results in wasted BTU's and a potential safety hazard for the homeowner. Closed Potable Hot Water system without THERM-X-TROL Backflow preventer, pressure reducing valve or meter causes expanded (heated) water to build pressure causing the relief valve to open resulting in: Wasted BTU's Shortened water heater life Wasted municipal water and sewer dollars Potential safety hazard for homeowner The Amtrol THERM-X-TROL ST-12 Expansion Tank is designed to eliminate this problem by providing control of maximum pressures at a level below the relief valve setting. It also provides an additional space in the system to accommodate the increased volume of water created by thermal expansion, returning it to the system when hot water delivery is demanded.

## Features

- Eliminates the waste of energy and water, thus saving money
- Prevents the relief valve from going off
- Protects the water heater and plumbing fixtures from premauture failure
- Eliminates the waste of energy and water, thus saving money
- Prevents a dangerous pressure build-up in the system

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Manufacturer | AMTROL |
| Part Number | ST-12 |
| Item Weight | 2.2 pounds |
| Product Dimensions | 8 x 11 x 15 inches |
| Item model number | ST-12 |
| Is Discontinued By Manufacturer | No |
| Size | one-size |
| Color | White |
| Power Source | Ac/dc |
| Item Package Quantity | 1 |
| Batteries Included? | No |
| Batteries Required? | No |
| National Stock Number | 5430-01-626-6547 |

## Images

![ST-12 Thermal Expansion Tank - Image 1](https://m.media-amazon.com/images/I/51Uq0ljbAXL.jpg)

## Questions & Answers

**Q: Is this for potable water?**
A: It is not made for potable water system. But in a regular installation some water from the tank can mix with a potable water. The tank has a polypropylene liner and butyl diaphragm, which may be in contact with water. You have to decide for yourself if you want to drink water from a polypropylene container.

**Q: Can this tank be install horizontally?**
A: Amtrol instruction says: "Mount tank vertically in downward position only. Ensure the piping can support the entire weight of the tank when full of water". This makes sense to me.

**Q: Is this compatable with ethylene glycol?  I want it for the glycol side of a heat exchanger on a solar water heater.**
A: I don't know. It may be best to contact the Amtrol technical support to see if ethylene glycol is compatible with the bladder diaphragm chemistry in this unit.

**Q: what's the capacity in gallons?**
A: It's a 12 liter tank, so it holds approximately 4.4 gallons.

## Frequently Bought Together

- Amtrol ST-12 Thermal Expansion Tank
- HoldRite QuickStrap Universal Expansion Tank Water Heater Wall Mounting Bracket, Stainless Steel, QS-U
- MEASUREMAN 0-200 PSI Water Pressure Gauge, 2-1/2'' Dial, Hose bib Pressure Gauge, Home Water Pressure Tester, Durable 3/4” Hose Thread, Water Pressure Gauge for Home

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**Shop now:** [https://www.desertcart.co.th/products/8847368-st-12-thermal-expansion-tank](https://www.desertcart.co.th/products/8847368-st-12-thermal-expansion-tank)

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*Product available on Desertcart Thailand*
*Store origin: TH*
*Last updated: 2026-02-16*