Vertical Expansion Vessel

Overview

The Vertical Expansion Vessel is a pre-charged bladder-type pressure vessel designed for use in closed-loop heating, cooling, and potable water pressure systems. Its floor-standing vertical orientation makes it ideal for plant rooms and installations where space efficiency and stability are priorities. Available in capacities ranging from 8 to 5,000 litres, the vessel accommodates a wide variety of system sizes — from small residential installations to large commercial and industrial plants.

Construction

The vessel shell is manufactured from robust carbon steel, providing excellent pressure resistance and long service life. Internally, a flexible bladder separates the system fluid from the pre-charged nitrogen gas cushion. Two bladder materials are available to suit different applications:

• EPDM (Ethylene Propylene Diene Monomer) — recommended for heating and cooling systems, offering excellent resistance to high temperatures and a wide range of system fluids.
• SBR (Styrene Butadiene Rubber) — suitable for potable water applications, providing reliable performance in domestic and commercial water pressure systems.

The nitrogen pre-charge is factory-set and can be adjusted on site to match system design pressure. Maximum working pressure is rated at 6 bar for standard models and up to 10 bar for high-pressure variants, ensuring compatibility with a broad range of system operating conditions.

Applications

Vertical expansion vessels are used across a wide range of building services and industrial applications, including:

• Closed-loop central heating systems in residential, commercial, and industrial buildings
• Chilled water and cooling circuits
• Potable water pressure boosting and storage systems
• Solar thermal and heat pump installations
• District heating and cooling networks

The vertical floor-standing design ensures a stable footprint and straightforward pipework connections, simplifying installation in plant rooms and equipment enclosures.

Compliance

All vessels are manufactured and tested in accordance with BS EN 13831 — the European standard for closed expansion vessels with an internal diaphragm or bladder for installation in water installations. This ensures consistent quality, safety, and performance across the full capacity range, and supports compliance with building regulations and system design standards.