Expansion Vessel Reflex NG 12 diaphragm heating system 6 bar / 120°C (white)

Reflex NG 12 diaphragm expansion vessel is designed for closed central heating systems to accommodate the thermal expansion of heating water. Rated for up to 6 bar of operating pressure and temperatures to 120°C, this compact white vessel helps stabilise system pressure and reduce stress on boilers, pumps and radiators. The diaphragm separates the water chamber from the pre-charged gas side, enabling reliable pressure compensation in domestic and light commercial sealed heating installations.

Advantages

The Reflex NG 12 provides precise pressure management through its internal diaphragm design, offering reliable separation between the water and gas sections to prevent waterlogging and loss of function. Its 6 bar pressure rating and 120°C temperature tolerance make it suitable for a wide range of central heating applications while the compact white enclosure supports discreet installation in plant rooms or near boilers. Construction focused on compatibility with sealed systems helps protect components from pressure spikes and reduces the need for frequent maintenance.

Suitable for

• Domestic central heating systems with sealed circuits
• Light commercial boiler installations and small plant rooms
• Radiator circuits and closed-loop hydronic heating systems
• Systems where space is limited and a compact expansion vessel is required

When it may not be suitable

The Reflex NG 12 is intended for closed (sealed) heating systems; it is not suitable for open expansion systems or applications that require higher pressure ratings than 6 bar. Systems operating continuously above 120°C or requiring larger expansion volumes than the NG 12 can provide will need a different vessel size or specification.

Key specifications

• Type: Diaphragm expansion vessel for heating systems
• Maximum operating pressure: 6 bar
• Maximum operating temperature: 120°C
• Application: Closed central heating and sealed hydronic systems
• Colour/finish: White exterior

How to use

Install the expansion vessel according to the system design and local regulations, typically on the return line near the boiler or pump where it can effectively absorb volume changes. Ensure the pre-charge pressure of the gas side matches the static system pressure or manufacturer guidance before filling the system. After installation, bleed any trapped air from the system and check for leaks; monitor system pressure during initial heating cycles and adjust pre-charge or isolation valves as required.

What to consider before purchase

• Confirm the vessel volume is appropriate for your system's water volume and expansion needs
• Verify the system's maximum operating pressure does not exceed 6 bar
• Ensure the vessel's temperature rating (up to 120°C) suits your application
• Check mounting space and connection orientation to fit the installation location

Usage recommendations

For reliable performance, set the vessel pre-charge to match the cold static pressure of the heating system, perform periodic visual and pressure checks, and replace the vessel if the diaphragm shows signs of deterioration or the unit becomes waterlogged. Follow local codes and the boiler manufacturer's instructions during installation and service.