Therm-X-Trol ST-12 - Water heaters and boilers Amtrol - Free user manual and instructions
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| Product Type | Expansion Tank for Water Heaters and Boilers |
| Brand | Amtrol |
| Model | Therm-X-Trol ST-12 |
| Category | Water Heaters and Boilers |
| Capacity | 12 Gallons (US) |
| Dimensions (Approx.) | 15 in. Diameter x 24 in. Height |
| Weight (Dry) | 22 lbs |
| Max Working Pressure | 150 psi |
| Max Operating Temperature | 200°F (93°C) |
| Tank Material | Steel with Butyl Rubber Bladder |
| Connection Size | 3/4 in. NPT (Female) |
| Pre-Charge Pressure | 40 psi (Adjustable) |
| Application | Potable Water and Hydronic Heating Systems |
| Maintenance | None Required (Sealed System) |
| Certifications | ASME, NSF 61, CSA |
| Features | Pre-charged Air Cushion, Corrosion-Resistant Lining |
| Warranty | 5 Years (Limited) |
Frequently Asked Questions - Therm-X-Trol ST-12 Amtrol
What is the purpose of the Therm-X-Trol ST-12 expansion tank?
The Therm-X-Trol ST-12 is designed to absorb thermal expansion in closed water heating systems, preventing pressure buildup and protecting your water heater or boiler from damage.
How do I size an expansion tank for my water heater?
Sizing depends on system volume and temperature. The ST-12 (12 gallons) is suitable for typical residential water heaters up to about 80 gallons, but always consult a professional for proper sizing.
What is the pre-charge pressure and how do I adjust it?
The factory pre-charge is 40 psi. You can adjust it using a standard air compressor with the tank disconnected from the system. The pre-charge should match the system static pressure.
Can the ST-12 be used in a radiant floor heating system?
Yes, it is suitable for hydronic heating systems, including radiant floors, as long as the system temperature and pressure are within the tank's limits (max 200°F and 150 psi).
What maintenance does the expansion tank require?
Minimal maintenance. Check the pre-charge pressure annually and ensure the tank is not leaking. The bladder is not user-replaceable; replace the entire tank if faulty.
How do I install the Therm-X-Trol ST-12?
Install vertically or horizontally on the cold water line near the water heater. Use proper support brackets if needed. Ensure the connection is tight and the tank is accessible for pressure checks.
What does the model number ST-12 signify?
The ST likely stands for 'Standard' or 'Steel' and 12 indicates the tank capacity in gallons.
Is the expansion tank suitable for potable water?
Yes, the ST-12 is made with a butyl rubber bladder and steel shell that are approved for potable water, meeting NSF 61 standards.
What is the typical lifespan of an expansion tank?
With proper installation and maintenance, a well-made expansion tank like the Therm-X-Trol can last 5-10 years or more. Factors include water quality and temperature.
How do I check if my expansion tank is working properly?
Tap the tank: a dull thud indicates water inside (bad), a hollow sound indicates air (good). Also, check the pressure with a tire gauge when the system is cold and static.
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USER MANUAL Therm-X-Trol ST-12 Amtrol
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Product information
Brand : Amtrol
Model : Therm-X-Trol ST-12
Category : Water heaters and boilers