Expansion vessel Reflex S 12 L (model 9702700) – membrane tank, 12 liters

The Reflex S 12 L expansion vessel is a membrane-type pressure tank with a 12-litre nominal volume designed for closed heating and hot water systems. The internal diaphragm separates the hydraulic medium from a precharged gas chamber to accommodate thermal expansion, stabilise system pressure and reduce stress on pumps, valves and piping. The compact steel shell and corrosion-resistant internal components make the vessel suitable for domestic boiler circuits and small closed-loop installations where reliable compensation of volume changes is required.

Advantages

The membrane design prevents direct contact between fluid and gas, reducing gas loss and prolonging diaphragm life while ensuring consistent pressure control. With a 12-litre capacity, the vessel provides measurable expansion compensation in small domestic systems without occupying excessive space. Built according to typical industry standards for expansion vessels, it offers straightforward integration, low maintenance requirements and reliable protection for system components against pressure fluctuations.

Suitable for

• Small domestic heating systems and single-boiler circuits
• Closed-loop hot water installations in apartments and small houses
• Domestic hot water buffer and circulation systems
• Systems requiring a compact membrane expansion vessel for pressure compensation

Key specifications

• Nominal volume: 12 litres
• Type: membrane (diaphragm) expansion vessel
• Application: closed heating and hot water systems
• Construction: steel shell with internal elastomer diaphragm
• Mounting: suitable for horizontal or vertical installation depending on system layout
• Connection: standard threaded hydraulic connection for system integration

How to use

Install the expansion vessel in the return or feed line of the heating circuit where it can access the system fluid and be isolated by appropriate valves. Precharge the gas side to the recommended pressure for the specific system, taking into account static height and desired operating pressure; check and adjust the precharge with a pressure gauge before filling the system. After installation, pressurise and vent the heating circuit according to the boiler and system manufacturer instructions, then verify that the vessel and system maintain correct operating pressure during heat-up and cool-down cycles.

Usage recommendations

Regularly check the gas precharge and overall vessel condition as part of routine system maintenance. Inspect for loss of precharge, diaphragm failure, or external corrosion, and replace the vessel if functional integrity is compromised. When selecting installation location and precharge pressure, follow the heating system design parameters and manufacturer guidance to ensure correct pressure compensation and system protection.