2.1 Gal. Inline Expansion Tank, Residential

Zilmet ZEP5 Inline Thermal Expansion Tank – 2.1 Gallon, 3/4" NPT, NSF Certified

The Zilmet ZEP5 is a 2.1-gallon inline thermal expansion tank engineered for use in potable water systems subject to thermal expansion from heating. Designed for closed-loop systems, it helps regulate pressure by absorbing excess water volume caused by temperature increases, preventing overpressurization of the plumbing system.

The tank features a welded steel shell with a seamless polypropylene liner and a high-grade butyl diaphragm, creating a separation between system water and the air charge. Its MIG-welded construction eliminates internal sharp edges, improving reliability and extending service life.

Product Features

• Capacity: 2.1 gallons (8 liters)
• Pre-Charge: Factory set; adjustable as required
• Construction: Welded steel tank with durable epoxy-polyester finish
• Liner Material: Virgin polypropylene, bonded to interior surface to resist cracking and delamination
• Diaphragm: Butyl rubber; low permeability for reduced air loss
• Connection: 3/4" NPT stainless steel female threaded fitting
• Mounting Orientation: Inline/horizontal installation

Performance Ratings

• Maximum Working Pressure: 150 PSI
• Maximum Temperature: 200°F (93°C)
• Diameter: 7.9 inches
• Height: 11 inches
• Certification: NSF/ANSI 61 compliant for potable water applications
• Warranty: 5 years (manufacturer limited)

Installation Notes

The ZEP5 is intended for installation on the cold-water supply line, downstream of the backflow prevention device or pressure-reducing valve. System pressure and tank pre-charge should be matched prior to final connection. Installation should be performed by qualified personnel in accordance with local plumbing codes and pressure system design criteria.

Recommended Applications

Designed for residential and light commercial water heating systems requiring expansion control. Suitable for use with standard and high-efficiency water heaters in closed systems where thermal expansion can result in elevated pressure and potential system stress.