4.8 Gal. Inline Expansion Tank, Residential

Zilmet ZEP12 – 4.8 Gallon Inline Thermal Expansion Tank for Potable Water Systems

The Zilmet ZEP12 is a 4.8-gallon inline thermal expansion tank engineered for closed potable water systems where thermal expansion control is required. It absorbs excess pressure caused by water heating cycles, helping to maintain system integrity and protect components downstream from pressure-related stress or failure.

Fabricated with a heavy-duty diaphragm and internal polypropylene liner, the tank separates water from the air charge to prevent internal corrosion and extend service life. MIG welds eliminate sharp edges and internal inconsistencies that could compromise structural integrity. This unit is suitable for residential and light commercial installations requiring consistent performance under variable load conditions.

Contractor-Focused Performance

Designed for horizontal or vertical installation, the ZEP12 offers flexible placement in confined utility spaces. The tank includes a stainless steel 3/4-inch connection for corrosion resistance and a protected Schrader valve for easy pre-charge adjustment. Its epoxy-polyester external coating protects against environmental wear, making it suitable for demanding conditions.

Key Product Features

• Factory Tested for Leaks – Quality-assured performance with 100% pressure testing at the manufacturing level.
• MIG Welded Construction – Promotes uniform weld seams, reducing weak points and ensuring consistent shell integrity.
• Polypropylene Liner – Isolates potable water from metal surfaces to reduce internal scaling and corrosion risk.
• Epoxy-Polyester Exterior – Durable finish resists damage from mechanical impact and environmental exposure.
• Stainless Steel Connector – Provides robust mechanical strength and long-term resistance to galvanic corrosion.
• Sealed Pre-Charge Valve – Maintains air pressure and facilitates service adjustments when required.

Specifications

• Nominal Volume: 4.8 gallons
• Maximum Working Pressure: 150 psi
• Connection Size: 3/4" NPT
• Tank Diameter: 10.6 inches
• Height: 13.7 inches
• Warranty: 5 years

Installation and Application Notes

The ZEP12 should be installed in compliance with local plumbing codes and pressure relief standards. Use in conjunction with backflow prevention or check valves where thermal expansion must be managed. Professional installation is recommended to ensure accurate system sizing, air charge balancing, and code compliance.