Solar Expansion Tank

The Solar Expansion Tank is a pre-charged pressure vessel engineered to manage fluid expansion in closed-loop solar thermal systems. As solar collectors heat the heat-transfer fluid, the fluid expands; this vessel absorbs that expansion safely, protecting pipework, pumps, and collectors from damaging pressure surges.

Construction

The tank features a robust carbon steel shell finished with a corrosion-resistant coating, paired with a high-temperature EPDM bladder that separates the system fluid from the pre-charged nitrogen cushion. EPDM is specifically chosen for its excellent resistance to elevated temperatures and glycol-based heat-transfer fluids.

Key Specifications

• Capacity range: 8 L to 200 L
• Maximum operating temperature: 120°C
• Maximum working pressure: 10 bar
• Connection size: 3/4" BSP

Fluid Compatibility

The EPDM bladder is fully compatible with water/glycol mixtures commonly used as antifreeze heat-transfer fluids in solar thermal installations. This ensures long-term bladder integrity even under continuous thermal cycling.

Compliance

Manufactured and tested in accordance with EN 13831, the European standard for closed expansion vessels with a flexible diaphragm for installation in water installations. This certification ensures the vessel meets rigorous safety and performance requirements.

Installation

The 3/4" BSP threaded connection allows straightforward integration into standard solar thermal pipework. The tank should be installed on the cold side of the circulation pump, in a vertical or horizontal orientation as specified by the manufacturer's guidelines. Pre-charge pressure should be verified and adjusted to match the system's static head before commissioning.