Amtrol ST-25V Thermal Expansion Tank

The Amtrol ST-25V Thermal Expansion Tank is a vertical, stand-type expansion solution designed for closed potable water systems. With a 10.3 gallon capacity and a 15" diameter by 19" height footprint, it accommodates thermal expansion while keeping system pressure stable. It features 3/4" female threaded inlet and outlet connections, a factory pre-charged air valve at 40 PSIG, and a heavy-duty butyl diaphragm for long-lasting performance.

Constructed with a urethane top-coated steel tank and an antimicrobial inner lining, the ST-25V protects potable water quality and resists corrosion. It is rated for up to 200°F and 150 PSIG, making it suitable for most closed potable water configurations. The inclusion of a projection welded air valve, turbulator water circulator, and stainless steel system connection ensures reliable operation and easy integration into existing systems. This tank is lead-free and complies with IAPMO R&T, ISO 9001, and NSF/ANSI 61 standards.

Backed by a 5-year warranty, the Amtrol ST-25V delivers dependable pressure control, reduced water hammer, and extended plumbing life in domestic and commercial installations.

• Capacity: 10.3 gal
• Vertical stand design with 15" Ø x 19" H footprint
• Inlet/Outlet: 3/4" female threaded
• Factory pre-charged air at 40 PSIG
• Heavy-duty butyl diaphragm; antimicrobial tank lining
• Includes projection welded air valve, turbulator circulator, stainless steel system connection
• Temperature rating: 200°F; Pressure rating: 150 PSIG
• Lead-free construction; compliance: IAPMO R&T, ISO 9001, NSF/ANSI 61