Expansion vessel Meibes BASEFLEX 12/1.5, 6 bar for central heating systems

Meibes BASEFLEX 12/1.5 is an expansion vessel for central heating systems with a nominal volume of 12 liters and a maximum working pressure of 6 bar. The vessel features a diaphragm design that separates the system water from the pre-charged gas cushion, allowing it to absorb volume changes in sealed heating circuits. It is intended for domestic and light-commercial heating installations where an autoclave-type diaphragm vessel is required to stabilise pressure and protect boilers, pumps and piping against pressure-related stress.

Advantages

The Meibes BASEFLEX 12/1.5 provides reliable pressure compensation in closed heating systems without the need to introduce additional water into the circuit. Its diaphragm construction reduces the risk of corrosion by preventing direct contact between the gas charge and system water. Designed for up to 6 bar operation, the vessel reduces pressure peaks and minimises cycling of boilers and circulator pumps, contributing to longer component life and more consistent system performance.

Suitable for

• Residential central heating systems
• Light-commercial heating installations
• Closed-loop radiator and underfloor heating circuits
• Systems requiring autoclave-type diaphragm expansion vessels

Key specifications

• Nominal volume: 12 litres
• Pre-charge pressure: 1.5 bar (factory setting)
• Maximum operating pressure: 6 bar
• Diaphragm (membrane) type design
• Application: closed central heating systems

How to use

Install the expansion vessel according to the heating system layout, typically on the return line close to the boiler or pump station and secured to avoid stress on piping. Confirm the pre-charge pressure matches system requirements and adjust with a suitable air valve and pressure gauge if necessary before filling the system. After installation, bleed trapped air from the circuit and verify system pressure under normal temperature conditions. Periodically check the vessel pre-charge and visual condition during routine boiler maintenance.

Usage recommendations

For correct function, verify the pre-charge pressure is appropriate for the static system pressure and adjust when the system is cold. Regularly inspect for leaks, diaphragm integrity and proper mounting. Follow local regulations and manufacturer guidance during installation and service.