Hydronic Balancing is the process of optimising the distribution of water in a building’s heating or cooling system so it provides the intended indoor climate at optimum energy efficiency and minimal operating cost.
To provide the correct power output heating or cooling devices require a certain flow known as the design flow. Theoretically it is possible to design plants that deliver the design flow at each terminal unit (heating or cooling device). In reality this is not possible because pipes and valves only come in certain sizes and accurately predicting the real flow in a system is too complex. Some circuits (typically those closest to the pump) will be favoured by higher than required flows at the expense of other circuits that will have underflows.
In small heating systems (e.g. domestic systems) balancing is quite easy because of the small number of terminal units and relatively simple distribution network. Balancing can normally be achieved by simply pre-setting the flow through the radiators.
Larger buildings, such as offices or hospitals, have a more complicated heating and cooling system and require a more accurate balancing technique. To obtain a plant with the correct design flows, consultants design systems to include balancing valves, differential pressure controllers or pressure independent control valves. Balancing valves allow the measurement of differential pressures which can be used to calculate a flow. There are various balancing methods but all involve measuring differential pressures and adjusting them to the correct value by calculating what flow that represents.
Differential pressure controllers are usually membrane- or spring driven valves that control the differential pressures in the installation. This will simplify balancing procedures and enable the installation to be more precisely controlled. Pressure independent valves combine the balancing and control functions in one valve and work based on springs and/or membranes to precisely control the flows in the distribution network and as such need no measuring or balancing procedure.
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