Expansion Vessel Comap Flofix for Domestic Hot Water 100 L, 10 bar, 3/4" Connection, White

The Comap Flofix expansion vessel for domestic hot water is a 100 L capacity tank designed to manage thermal expansion in central domestic hot water (DHW) systems. Rated to 10 bar with a 3/4" connection and a white finish, this vessel integrates into DHW installations to stabilise pressure, reduce on/off cycling of pumps and valves, and protect pipes and fittings from pressure surges. Its size and specification make it suitable for residential and small multi-family systems where reliable pressure management is required.

Advantages

The vessel provides a dedicated buffer for expanded water volume, helping to maintain consistent system pressure and reduce stress on circulation pumps and safety valves. The 10 bar rating ensures compatibility with typical domestic plumbing pressures, while the 3/4" connection enables straightforward installation on common DHW lines. The white exterior offers a neutral appearance suitable for visible installations in utility rooms or service cabinets.

Suitable for

• Residential domestic hot water systems up to medium capacity (100 L expansion requirement)
• Boiler and indirect water heater installations requiring thermal expansion control
• Installations where reduced pump cycling and improved valve longevity are desired
• Visible or utility-room installations where a neutral white finish is preferred

When it may not be suitable

This 100 L expansion vessel may not be appropriate for very large commercial or industrial hot water systems that require greater expansion capacity or higher working pressures than 10 bar. It is also not intended as a replacement for potable water storage tanks or as the primary water heater; it functions specifically to accommodate expansion within closed DHW circuits.

Key specifications

• Volume: 100 litres
• Maximum working pressure: 10 bar
• Connection size: 3/4"
• Intended application: domestic hot water (DHW) expansion
• Finish: white

How to use

Install the expansion vessel on the cold or hot side of the DHW circuit according to local plumbing codes and the system designer's recommendations, ensuring the 3/4" connection is compatible with the existing piping. Pre-charge the vessel to the system's static pressure using a pressure gauge and an air valve; verify that the pre-charge matches the installation requirements. Once connected, commission the system by slowly bringing the water to working temperature and checking for correct pressure behaviour, leaks, and that pump cycling is reduced. Periodic inspection of the pre-charge and visible condition of the vessel is recommended as part of routine maintenance.

What to consider before purchase

• System volume and expected thermal expansion to confirm 100 L capacity is sufficient
• System working pressure and compatibility with a 10 bar maximum rating
• Connection type and pipework compatibility with a 3/4" inlet
• Available space and whether a visible white finish is acceptable for the installation location

Usage recommendations

For reliable operation, set the vessel pre-charge to match the static pressure of the cold system before connection, and re-check the pre-charge annually. Ensure all fittings and safety devices are sized and set according to local regulations and manufacturer guidance to maintain system protection and longevity.