Expansion vessel Reflex NG 8 diaphragmatic 6 bar / 120°C – model 7230107

Reflex NG 8 diaphragmatic expansion vessel is designed for central heating systems where thermal expansion of the heating fluid needs safe compensation. The compact vessel is rated for a maximum working pressure of 6 bar and can withstand temperatures up to 120°C. As a diaphragm-type vessel, it separates the system water from the pre-charged gas cushion, helping to stabilise system pressure, reduce water loss and protect installation components against overpressure.

Advantages

The Reflex NG 8 uses an internal elastomer diaphragm to reliably separate liquid and gas, providing quick response to pressure changes and minimising contact between system water and the gas cushion. Its compact size suits installations with limited space, while the 6 bar rating and 120°C temperature capability make it compatible with most residential and light commercial heating circuits. The vessel's construction reduces the need for frequent topping-up and helps maintain consistent boiler and pump performance.

Suitable for

• Domestic central heating systems with expansion requirements up to 6 bar.
• Light commercial boiler installations where a compact diaphragm vessel is required.
• Replacement of existing small expansion vessels in confined plantrooms or underfloor cabinets.

When it may not be suitable

This expansion vessel is not intended for systems requiring working pressures above 6 bar or continuous operation above 120°C. It is also not suitable where a membrane-free (open) expansion solution is required, or where specialised materials (for aggressive fluids or non‑standard heating media) are necessary. For larger systems with high fluid volumes, a higher-capacity vessel should be selected.

Key specifications

• Vessel type: Diaphragmatic (membrane) expansion vessel.
• Maximum working pressure: 6 bar.
• Maximum temperature rating: 120°C.
• Application: Central heating systems (residential and light commercial).
• Design feature: Compact form factor for installations with limited space.

How to use

Install the Reflex NG 8 on the return pipe close to the boiler or system manifold, following local regulations and manufacturer installation instructions. Ensure the vessel pre-charge is set to the system filling pressure (typically slightly below the static system pressure) before connecting to the system. After installation, pressurise and bleed the system, then verify that the vessel and safety devices maintain stable pressure under normal operating conditions. Regular visual checks and periodic inspections of pre-charge pressure are recommended as part of routine system maintenance.

What to consider before purchase

• Confirm the vessel's 6 bar maximum working pressure meets your system requirements.
• Check the operating temperature of your system does not exceed 120°C.
• Verify available installation space and connection orientation for the compact vessel.
• Ensure diaphragm-type vessels are compatible with your heating fluid and any additives in use.

Usage recommendations

Use the vessel with a correctly set pre-charge pressure and include routine checks of diaphragm integrity and pre-charge to ensure long-term performance. If system upgrades increase volume or pressure requirements, reassess vessel capacity and replace with a larger model if necessary.