Expansion Vessels & Unvented Kits
Expansion Vessels fulfil a vital role in an unvented water heating system. Often sold as part of an "unvented kit" with vital pressure-reducing valves, check valves, and a tundish. Expansion vessels act as a buffer space, filling with air when pressure builds up to ensure a steady and safe flow of water at a consistent pressure. When water gets hot and expands, expansion vessels allow space for air, ensuring that as water expands and contracts, the water pipes do not swell and burst. Expansion vessels function like a diaphragm, with a pre-charged pocket of air that is compressed as the water heater expands. Use of an expansion vessel is often of vital importance in unvented systems and central heating water circuits; most manufacturers would void a warranty on an unvented water heater system without one.
We proudly offer full unvented kits on any water heaters 30 Litres and over on the website within the price shown. If you are looking at a smaller unvented water heater, don't hesitate to get in touch with us to help deduce the most appropriate expansion vessel for your needs.