Expansion Vessel Unimet DART.2.CO-5L — 5 L, Heating System, 6 bar

Unimet DART.2.CO-5L is a 5-litre expansion vessel engineered for closed central heating systems with a maximum operating pressure of 6 bar. It compensates for thermal expansion of the heating medium to stabilise system pressure, reduce pressure fluctuations and protect boilers, pumps and piping from overpressure and frequent relief-valve cycling. The compact design allows inline installation with existing piping systems in domestic and small commercial boiler installations.

Advantages

The expansion vessel provides reliable pressure damping through a pre-charged gas chamber separated from the heating medium by an internal diaphragm, ensuring predictable expansion control and minimizing waterlogging. Its 5-litre capacity and 6 bar maximum rating make it suitable for small to medium closed systems, delivering steady performance without requiring large installation space. Built for compatibility with standard heating components, it helps extend component life and reduces maintenance interventions caused by pressure-related faults.

Suitable for

• Domestic central heating systems
• Small commercial boilers and hydronic installations
• Heating circuits requiring pressure stabilization and protection
• Retrofit installations where inline mounting is needed

Key specifications

• Nominal volume: 5 litres
• Maximum operating pressure: 6 bar
• Type: closed system expansion vessel with internal diaphragm
• Intended medium: water or water-glycol mixtures commonly used in heating systems
• Mounting: inline connection compatible with standard heating pipework
• Application: designed for domestic and small commercial heating circuits

How to use

Install the expansion vessel in the heating system piping according to the system layout, positioning it where it can relieve pressure fluctuations effectively — typically near the boiler or on the feed/return line. Ensure the vessel is pre-charged to the correct air pressure for the system’s static pressure before filling; adjust the pre-charge using a standard air valve and pressure gauge. After installation and pre-charge adjustment, fill the system and check for leaks, correct operating pressure and proper diaphragm response during heating cycles.

Usage recommendations

Verify the system’s required pre-charge pressure and confirm compatibility with water-glycol mixtures if antifreeze is used. Periodically inspect the vessel for external damage and check the gas pre-charge pressure during scheduled maintenance to ensure continued pressure control and to prevent waterlogging.