A buffer tank is a separating element that hydraulically isolates the primary (producer) and secondary (consumer) circuits of heating and cooling systems, thus dampening flow and temperature fluctuations. It prevents sudden load variations at the boiler, cascade system, or chiller outlet from generating thermal stresses on the heat source, reduces back pressure and flow resistance in pumps, and ensures stable, quiet, and efficient operation while extending equipment life.

A buffer tank is recommended in systems with multiple pumps and variable-flow consumers, cascade boiler or chiller applications, installations with a high density of three-way valves, and in any case where the producer and consumer flow rates differ. It allows the primary circuit to maintain its optimal flow rate, while the secondary circuit adapts freely to demand, thus preventing common problems such as short circuits at low load, insufficient flow at high load, and heat surges.

The design aims to create a low flow velocity within the housing, thus minimizing pressure losses and optimizing the separation effect. In practice, it is essential to select a very low internal velocity and determine the appropriate diameter and height based on the total flow rates of the primary and secondary collectors. The unit is typically positioned near the heat generator and the primary pump suction. Short, symmetrical connections are preferred with the secondary collectors. A vent is connected to the upper point, a drain to the lower point, and sleeve probe housings are used for temperature monitoring if required.

The material for the buffer tank body is selected based on the system's water chemistry and operating conditions. While carbon steel is commonly used in centralized systems, stainless steel is preferred for applications with a high risk of corrosion. Connections can be flanged, threaded, or welded, depending on the project; the PN class and test pressure are determined based on the operating pressure and temperature. Buffer tanks are manufactured in accordance with applicable quality requirements and undergo factory testing to verify their leak-tightness and strength.

Before commissioning, it is important to verify the proper functioning of all drain points, active aeration, and the connection of the bottom drain to a secure drainage pipe. Periodic visual inspections, monitoring of temperature variations and pump operating points, and regular sediment removal (if using a monobloc system) are sufficient. These simple maintenance operations protect the heat source from thermal shock, the pumps from hydraulic stress, and ensure high system efficiency over the long term.