Expansion Vessels


Mibec can supply a full range of expansion vessels for heating systems, or for potable water applications. Mibec vessels can range in size from 2 litre for use in instantaneous water heater applications, all the way up to 700 litres or even more for use on larger biomass or commercial applications.

An expansion vessel is a tank used to protect closed water heating systems and domestic hot water systems from excessive pressure caused by water hammer and thermal expansion of the water inside the sealed system. An expansion vessel is usually split into two compartments divided by a diaphragm. One side is connected to the heating systems pipework and is filled with water; the other side contains a gas such as nitrogen under pressure. As the water pressure in the heating system increases the diaphragm will push outwards, compressing the gas and therefore absorbing the excess pressure. The diaphragm arrangement helps to prevent the undesired transfer of air, and helps maintain low levels of oxygen within the pipes, reducing corrosion in the system reducing maintenance requirements and increasing the service life.

Mibec supply expansion vessels from leading brands including Reflex, Zilmet and Varem, all from stock in the UK. All vessels are approved to latest European standards, and have an outer epoxy coating for protection.

Please feel free to email or call our support department on 01782 959170 where one of our trained advisers will be happy to help size an expansion vessel for your project.