2 Gal. Hydronic Heating Expansion Tank

Zilmet ZHT8-15 – 2 Gallon Hydronic Heating Expansion Tank

The Zilmet ZHT8-15 is a 2-gallon diaphragm expansion tank engineered for closed-loop hydronic heating systems. Designed to manage thermal expansion within sealed systems, this model stabilizes pressure fluctuations that occur as heating fluid volume increases with temperature. It is suitable for residential applications with limited space and moderate system fluid volume.

The tank features a welded carbon steel body, synthetic SBR rubber diaphragm, and a factory pre-charge. Its compact design allows for integration into tight mechanical spaces while delivering consistent performance across a wide range of operating conditions.

Construction and Functional Features

• Capacity: 2 gallons
• Maximum Working Pressure: 60 psi
• Connection Size: 1/2" NPT (side outlet)
• Shell Material: Carbon steel with corrosion-resistant external coating
• Diaphragm Material: Certified synthetic SBR rubber, seamless and replaceable

Application and Integration

• Closed-Loop Heating Systems: Designed for use in systems with water or glycol-based heating fluids
• Compact Profile: Small footprint allows for wall-mounted or bracketed installation in confined utility areas
• Pressure Stability: Absorbs excess system pressure and prevents overexpansion-related component fatigue
• Field-Adjustable Air Charge: Factory pre-charged and adjustable to match system fill pressure at installation

Installation Considerations

Install the ZHT8-15 on the system return line, upstream of the circulator and downstream of the boiler or heat exchanger. Ensure the tank is mounted in a vertical orientation with sufficient clearance for service access. Verify the tank's air pre-charge using a pressure gauge prior to filling the system. Installation should follow local plumbing and mechanical codes. Licensed HVAC or plumbing professionals are recommended for proper sizing and setup.

Use Case and System Compatibility

Appropriate for small residential hydronic systems including baseboard, radiant, and panel radiator installations. The 2-gallon capacity is best suited for systems with low static pressure and relatively small fluid volumes requiring reliable pressure compensation in a closed loop.