Expansion vessel VAREM LR CE 25 L, 3/4" gas connection, max 6 bar

The VAREM LR CE 25 L expansion vessel is a diaphragm-type pressure vessel with 25 litres nominal capacity, designed for closed heating and hot water systems. It has a 3/4" gas-side valve connection and is rated for a maximum working pressure of 6 bar. The vessel is factory pre-charged on the gas side and provides a water-side connection suitable for boilers, heat pumps and solar thermal circuits. Its function is to absorb thermal expansion, stabilise system pressure and reduce cycling of pumps and thermostatic devices.

Advantages

The expansion vessel uses a separating diaphragm to isolate the gas pre-charge from the system water, minimising gas diffusion and allowing consistent pressure control. With a 25 L capacity and 6 bar maximum working pressure, it is suitable for typical domestic and light commercial heating and hot water installations. The 3/4" gas connection simplifies topping up and service, while the compact cylindrical design facilitates installation in tight plant rooms or near the heat source. The product is compatible with common system fluids and can be mounted vertically or horizontally following manufacturer guidance.

Suitable for

• Domestic and small commercial closed heating systems
• Domestic hot water (DHW) systems and indirect cylinders
• Boiler installations and combi-boilers
• Heat pump buffer and circulation systems
• Solar thermal circuits with closed-loop operation

Key specifications

• Nominal volume: 25 litres
• Maximum working pressure: 6 bar
• Valve connection (gas side): 3/4"
• Diaphragm (separating membrane) type vessel
• Factory pre-charged gas side
• Suitable for closed heating and solar systems
• Compact cylindrical construction for wall or floor mounting

How to use

Install the expansion vessel on the system pressure line according to system design and local regulations, typically on the return line near the heat source. Before connection, verify the pre-charge pressure on the gas valve and adjust to the required setpoint for the specific system (static pressure without water). After making hydraulic connections, bleed the system to remove trapped air and check for leaks. Commission the system while monitoring pressure changes during a controlled heat-up to confirm correct vessel sizing and operation.

Usage recommendations

Check the vessel pre-charge periodically and re-pressurise when the system is cold to the required static pressure. Use corrosion-inhibited water where specified and follow local codes for pressure limiting and safety devices to ensure the expansion vessel protects piping and components effectively.