Expansion/Diaphragm Vessel CIMM ACS 18 L for Domestic Hot Water, Pressure 2.5/8 bar, Temp -10 to 100 °C

CIMM ACS 18 L expansion/diaphragm vessel is designed for domestic hot water systems to manage pressure variations and thermal expansion. The vessel has an 18-litre nominal volume and an internal diaphragm that separates the potable water from the pre-pressurised gas chamber, ensuring corrosion-resistant operation. It is suitable for installation on boilers, water heaters and circulation systems where maintaining stable pressure and preventing overpressure events are required. The product is rated for operating pressures of up to 2.5/8 bar and operates across a temperature range from -10 °C to 100 °C.

Advantages

The diaphragm design provides reliable separation between water and gas, reducing the risk of corrosion and prolonging service life compared with non-diaphragm vessels. Its 18 L nominal capacity balances compact dimensions with sufficient volume to accommodate thermal expansion in domestic hot water systems. The specified pressure and temperature ratings allow for use with a wide range of residential boilers and water heaters. The vessel supports easier pressure management and reduces cycling of pumps and valves by absorbing pressure spikes and stabilising system pressure.

Suitable for

• Domestic hot water systems (c.w.u.)
• Boilers and water heaters
• Circulation and distribution networks in residences
• Pressure stabilisation and thermal expansion compensation

Key specifications

• Nominal volume: 18 litres
• Operating pressure range: up to 2.5/8 bar
• Operating temperature range: -10 °C to 100 °C
• Internal diaphragm separating fluid and gas
• Intended for potable hot water applications

How to use

Install the expansion vessel according to system layout, mounting it on the cold or hot water line as specified by the system design and local regulations. Pre-charge the gas side to the recommended pressure for the system, taking into account static head and manufacturer guidelines. Connect the vessel using appropriate fittings and support it to avoid stress on pipework. After installation, check for leaks, verify pre-charge pressure and monitor system pressure during initial operation to ensure correct integration.

Usage recommendations

Ensure the pre-charge pressure is adjusted to match the static pressure of the installation; periodically inspect the diaphragm for integrity and check the vessel’s pre-charge every 6–12 months. Avoid exposure to freezing conditions beyond the specified limits and follow local plumbing codes for safe and compliant installation.