13.2 Gal. Hydronic Heating Expansion Tank

Zilmet ZHT50F – 13.2 Gallon Hydronic Expansion Tank for Closed-Loop Heating Systems

The Zilmet ZHT50F is a 13.2-gallon diaphragm expansion tank engineered for closed hydronic heating systems. It accommodates thermal expansion in hot water loops, helping to maintain stable system pressure and reduce mechanical stress on boilers, pumps, and valves. This model is well-suited for mid-sized residential or light commercial heating applications where consistent pressure control is essential.

The tank features a high-quality synthetic diaphragm that separates system fluid from the air pre-charge. The internal construction is designed to resist fatigue from pressure fluctuations, while the external shell is protected with a corrosion-resistant coating for extended service life.

Design and Construction Features

• Nominal Capacity: 13.2 gallons
• Shell Material: Carbon steel with external epoxy-polyester finish
• Diaphragm Material: Synthetic SBR rubber (heat- and pressure-resistant)
• Connection: 3/4" NPT side outlet
• Maximum Working Pressure: 60 psi

Functional Characteristics

• Pre-Charged Design: Air chamber comes factory charged and is field-adjustable to match system static pressure.
• Internal Separation: Diaphragm separates air and fluid to prevent waterlogging and maintain consistent drawdown.
• Side Connection Port: Welded stainless steel connection allows secure integration into closed-loop systems.
• MIG Welded Seams: Smooth, uniform welds enhance structural reliability and reduce internal stress points.

Installation Requirements

The ZHT50F is designed for vertical wall or floor-mounted installation in closed heating loops. It should be located near the boiler or circulator return, ideally at the system’s lowest pressure point. Installers should verify system fill pressure and adjust the tank’s air charge accordingly. All work must conform to applicable codes and system design parameters. Installation by qualified personnel is recommended.

Application Scope

This model is compatible with glycol-based and water-based closed heating systems. Its compact form factor and mid-range capacity make it a practical solution for multi-zone residential hydronic systems and low-rise commercial installations where consistent pressure control is required.