Saunier Duval Expansion Vessels also sometimes called expansion tanks or pressure vessels are a component fitted internally to Saunier Duval Combi type
and sealed system boilers and it's function is to compensate for the expansion of hot water, as water will expand when heated producing a rise
in pressure within the sealed or closed system. There is a menbrane or diaphragm within the vessel which separates the water from the air and
this allows the water to expand. All our Saunier Duval Expansion Vessels are new and genuine manufacturer spares.