Expansion vessel (diaphragm) INVENA CM 8L CW-11-008 — 8 liter capacity

Diaphragm expansion vessel INVENA CM 8L (model CW-11-008) is an 8-liter pressure vessel designed for closed heating and domestic water systems. The internal flexible diaphragm separates the air cushion from the system fluid, allowing the vessel to absorb thermal expansion, reduce pressure fluctuations and protect pumps, valves and pipework. The compact design and corrosion-resistant materials make this expansion vessel suitable for small boilers, heating circuits and auxiliary closed hydraulic installations.

Advantages

The diaphragm design provides fast response to pressure changes while preventing bladder contact with the system fluid, which reduces the risk of contamination and prolongs service life. The 8‑liter capacity is optimized for small domestic systems and secondary circuits, offering effective pressure compensation without excessive space requirements. The vessel’s construction allows for straightforward installation and maintenance in residential and light commercial applications.

Suitable for

• Small gas or electric boilers in single-family homes
• Secondary heating circuits and radiators
• Closed domestic hot water systems
• Closed hydraulic circuits in small commercial installations

Key specifications

• Nominal volume: 8 liters
• Diaphragm-type internal separation between air and fluid
• Application: closed heating and domestic water systems
• Purpose: compensate thermal expansion and reduce pressure spikes
• Compact design suitable for wall- or floor-mounted installation

How to use

Install the expansion vessel on the system return line or at the location recommended by the heating system manufacturer, ensuring correct orientation and secure mounting. Pre-charge the air side to the required pressure for the system (matching the static pressure of the installation) before commissioning. After connection, bleed air from the system and verify operating pressure and tightness. Periodically check the pre-charge pressure and the vessel for signs of external damage or leaks as part of regular system maintenance.

Usage recommendations

Before installation, consult the boiler or system manufacturer’s documentation to confirm appropriate pre-charge pressure and recommended mounting position. Use compatible fittings and isolation valves to allow removal or replacement without draining the entire system. If the diaphragm shows loss of function or leakage is detected, replace the vessel to maintain system protection.