Built for sealed heating (EN 12828) and chilled-water systems, Flexcon Premium Expansion Vessels stabilise system pressure by absorbing thermal expansion so plant runs safely and efficiently.

A new TPO (thermoplastic polyolefin) diaphragm on 1235 Ltrs models delivers high flexibility and extremely low permeability, helping the pre-charge hold for longer. Lighter construction cuts material use and transport emissions; packaging is FSC-certified to reduce CO₂ impact.

• Sustainable design lighter TPO membrane uses up to 50% less material
• Long service life 15-year warranty
• Low permeability pre-charge pressure maintained for longer
• Heating & cooling suitable for LPHW and CHW installations

Vessels comply with EN 13831 and the Pressure Equipment Directive 2014/68/EU. Red epoxy powder coating (RAL 3002). Flexcon Premium 3580 are supplied with feet and a mounting kit.

Flamco Flexcon Expansion Vessel - 425Ltr - Engineered for EN 12828 heating and chilled-water systems, this Expansion Vessel stabilises sealed system pressure by absorbing thermal expansion in LPHW/CHW applications.

Maximum working pressure: 10.0 bar.

Vessels in accordance with EN13831.

Suitable for systems with a maximum system temperature of 120 °C.

Minimum/maximum temperature diaphragm: -10 / 90 °C.

Suitable for addition of glycol-based anti-freeze up to 50%.

A flexible rolling diaphragm with a ribbed profile prevents sticking and encourages inflow at the slightest pressure rise, while a nitrogen pre-charge helps maintain set pressure longer. The uncoated connection thread supports quick, watertight installation.

• Rolling-diaphragm design for smooth expansion control
• Nitrogen pre-charge for extended pre-pressure retention
• Top-quality steel with epoxy-powder finish
• Factory tested for reliability

Built for long service life in domestic, commercial and industrial plant rooms, with continuous medium temperatures from −10 to 70 C.

Purpose-built for solar thermal circuits, the Flexcon Solar 8/2.5 [8Bar] expansion vessel supports sealed systems in line with EN 12828, keeping pressure stable in high-temperature applications.

A preformed butyl rolling diaphragm with extremely low permeability helps retain pre-charge, while a nitrogen fill limits corrosion and pressure loss. The clench ring clamps the diaphragm evenly to prevent damage, and a ribbed profile avoids sticking for instant inflow. An uncoated connection thread aids watertight installation; the steel vessel is finished in a gleaming epoxy-powder coat and factory tested.

• Solar-ready expansion vessel for sealed systems
• Butyl rolling diaphragm with very low permeability
• Nitrogen pre-charge for longer pressure stability
• Clench ring construction for a robust, uniform seal

For 880 Ltrs models: both halves are coated before assembly to protect the clamp ring, and the nitrogen valve is countersunk and covered. Continuous medium temperature range −10 to 110 C.

Mains Liquid Boosting Setup

The Mainsboost 350 litre vertical composite vessel with 22 mm connections is installed directly onto the incoming liquid supply and under mains pressure fills with water. When the chamber is full the pump reaches a state of pressure equilibrium. The Mainsboost system now has a volume of pressurised water ready for distribution throughout the property and where required can be supplied with multiple vessels options.

The 2 vessel Mainsboost 350 litre vertical composite system with 22 mm connections are installed directly onto the incoming water supply and under mains pressure fills with water. When the chamber is full the pump reaches a state of pressure equilibrium. The Mainsboost system now has a volume of pressurised water ready for distribution throughout the property.

The 3 vessel Mainsboost 350 litre vertical composite system with 22 mm connections are installed directly onto the incoming water supply and under mains pressure fills with water. When the chamber is full the pump reaches a state of pressure equilibrium. The Mainsboost system now has a volume of pressurised water ready for distribution throughout the property.

Vessels to protect Flexcon expansion vessels on elevated temperature systems. The vessels are fitted in between the expansion vessel and the system return. System water flows from the installation into the top of the vessel. From the bottom of the vessel, significantly cooler water is fed into. Capacity 350 Ltr.