Automatic balancing valves are utilised in central heating and cooling systems that rely on flow of water through the system. They use the latest flow technology to ensure that the design flow rate is achieved at all times irrespective of any pressure changes within the system.

A cooling or heating water distribution system is in balance when the flow in the whole system (through the component terminal lines, distributing lines and main distributing lines) corresponds to the flow rates that were specified for the design of the system. If the correct balancing of the system is not established, this will result in unequal distribution of the flow, so that there will be a surplus effect in some of the terminals, whereas the effect will be inadequate in others. As a consequence, the required heating or cooling will not be ensured in all parts of the installation. Practically, it is not possible to achieve a completely balanced system by manipulation of the piping or alteration of the pipe dimensions only. Only a correct set of balancing valves can ensure the correct distribution of the flow in the system.

In a variable primary chilled-water system, the design flow rate is determined by the water flow velocity in the tube of the coils.

Automatic balancing systems can be classified as constant-flow or variable-flow.

Until recently, constant flow systems were standard in heating, ventilation and air-conditioning (HVAC) systems. Constant flow uses a straightforward and simple design that can be applied to a broad range of projects. This involves the use of a fixed-speed pump that is set to the maximum load of the system. In addition, double-regulating balancing valves are manually set to regulate the impact of pressure changes across the system.

CAV (constant air volume) systems are mainly used in offices made up of a single area (e.g. open plan), where the temperature of the supply air is varied in response to a thermostat.

This type of system can also be used in offices with different areas and different loads: in this case the temperature of the supply air emitted into the different zones can be varied through use of a hot-water supplied re-heat coil located in the air duct leading to the related zone; alternatively, double duct systems can be used where two separate ducts for hot and cold air lead into a mixing box where the two flows are mixed together.

This type of system enables precise temperature control, but is more suitable for small offices. The necessary air ducts takes up a lot of space and are expensive to install, and they can also waste energy during the mid-seasons, where there might be simultaneous requests for heating or cooling in different parts of the office