Hydronic Expansion Tank – 2.1 Gallon, 1/2" MNPT – Closed-Loop Heating System Expansion Tank – ETX-15 Replacement

Key features

• Designed for Closed-Loop Hydronic Heating Systems - Engineered for boilers, radiant heat, and other closed-loop systems where thermal expansion must be controlled. Not for domestic potable water.
• 2.1-Gallon Capacity with Pre-Charge at 12 PSI - Ships factory-pre-charged to 12 PSI for standard hydronic setups. Pressure can be adjusted on-site using the included Schrader valve.
• 1/2" MNPT Connection – Direct ETX-15 Replacement - Features a standard 1/2" MNPT system connection commonly used in residential and light commercial heating systems. Compatible as a replacement for ETX-15-type expansion tanks.
• Durable Steel Construction with Butyl Diaphragm - Heavy-gauge steel shell and a long-life butyl rubber diaphragm keep water separated from air, preventing corrosion and providing consistent system pressure control.
• Vertical or Horizontal Mounting Options - Compact 8" diameter x 12.5" height size allows easy installation in tight mechanical rooms or equipment areas.

This 2.1-gallon hydronic expansion tank is built for closed-loop boiler and radiant heating systems, where thermal expansion must be managed to maintain safe, stable system pressure. The tank arrives pre-charged to 12 PSI, the standard setting for most residential hydronic systems, and includes a Schrader valve for pressure adjustment when needed. The interior butyl rubber diaphragm separates the air charge from system water, preventing internal corrosion and preserving long-term performance. With a 1/2" MNPT connection, this tank is a direct replacement for ETX-15-style expansion tanks and is compatible with most residential hydronic boilers. Not for potable water use. This model is intended for closed-loop heating applications only.

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