Expansion Vessel Meibes BASEFLEX 35/1.5, 6 bar for Central Heating

Meibes BASEFLEX 35/1.5 is an expansion vessel engineered for central heating systems. With a 35-litre volume and a 1.5 bar factory pre-charge, the unit is rated to withstand system pressures up to 6 bar. The vessel accommodates thermal expansion of the heating medium, helps stabilise system pressure and reduces cycling of pumps and boilers, supporting longer component life and steady operation in residential and light commercial installations.

Advantages

The diaphragm design separates the heating medium from the gas cushion to maintain stable pre-charge and reliable expansion capacity. Compact cylindrical construction allows straightforward mounting in plant rooms or utility spaces. Rated for 6 bar operation, the vessel is suitable for higher-pressure domestic and small commercial circuits where increased expansion volume and pressure control are required. Installation and maintenance are simplified by standard connection options and accessible pre-charge valve.

Suitable for

• Domestic central heating systems
• Light commercial heating installations
• Systems requiring a 35-litre expansion capacity
• Circuits with maximum operating pressures up to 6 bar

Key specifications

• Nominal volume: 35 litres
• Factory pre-charge: 1.5 bar
• Maximum allowable pressure: 6 bar
• Diaphragm-type separation between gas and fluid
• Orientation: vertical (cylindrical) mounting

How to use

Install the expansion vessel on the return line of the heating circuit in a location that allows access to the pre-charge valve for periodic checks. Ensure the system is depressurised and drained as required before making connections. Connect using appropriate fittings and isolate valves to allow service without draining the full system. Verify and adjust the vessel pre-charge to match the static system pressure before commissioning. After installation, pressurise the system and check for leaks and correct pressure behaviour during a controlled heat cycle.

Usage recommendations

Check the pre-charge pressure at least annually and after any maintenance that involves draining the heating circuit. Match the vessel pre-charge to the static pressure of the system to ensure correct expansion compensation. Do not exceed the vessel's rated maximum operating pressure and follow local regulations and manufacturer guidance for safe installation and service.