What is a buffer vessel?
What is a buffer vessel? A buffer vessel is a water-filled storage vessel that is installed as part of a heating or chilled-water system and is designed to increase the total amount of water circulating in the system. They are often used with heat pumps, boilers, chillers, underfloor heating, fan-coil units and other hydronic systems where stable flow and temperature control are important.
The main objective of a buffer vessel is to prevent the heat source or chiller from switching on and off too often. They call it short cycling, which can increase wear; reduced effectiveness of compressors and other parts leads to reduced operating life of the plant equipment. By adding additional water volume, the buffer vessel enables the system to gradually absorb or release energy, contributing to longer and more stable operation periods for the heat source.
A buffer tank may also be used to hydraulically decouple the primary circuit with the boiler, heat pump or chiller and the secondary circuit to radiators, underfloor heating or cooling terminals. Four-port buffer vessels are typically employed for this purpose, because they allow the primary and secondary pumps to run at separate flow rates without affecting each other.
Buffer vessels are available in various sizes, often made of carbon steel or stainless steel. Usually they are insulated so as to limit heat gain (in chilled water systems) or heat loss (in heating systems). Our full range of buffer vessels are detailed on two of our webpages – Buffer vessels from 30 to 6,000 Litres or our low height buffer vessel options (which are designed to fit into a standard floor height of a commercial or industrial building) are here – Low height buffer vessels or tanks from 1,500 to 5,000 litres
The amount of vessel required depends on the output of the system, minimum running duration, variation in water temperature and volume of water already present in pipes and equipment. Therefore, a buffer vessel should be selected as part of the entire system design, not just added without consideration and calculation.
