System equipment, such as chillers and individual terminal units, is the heart of any HVAC system. Extreme care and time is dedicated to their selection and performance criteria. However, without proper flow through these units, their efficiencies and heating or cooling transfer capabilities are altered.
By specifying automatic balancing, the designer is assured that the system is accurately and dynamically balanced. This means that all components will perform as specified regardless of changes. With automatic flow regulators, the terminal units will not exceed design flow even after modifications or additions to the system. In a proportionally (manually) balanced system, such changes can cause overflow unless adjustments are made at risers, branches and terminals.
Automatic balancing offers a number of other benefits such as: pump energy savings, lower head requirements and less balancing labor. These and other features are discussed in detail in the following sections.
Automatically balanced systems are certified to be accurate within five percent. Manually balanced systems are generally considered to be only 15 percent accurate.
Saves Pump Energy
Proper waterside balancing can typically save ten percent of the Brake Horse Power (BHP) when compared to an unbalanced system. This is why almost every hydronic system is balanced either manually or with AutoFlow. AutoFlow valves achieve system balance as soon as the pumps are turned on.
AutoFlow units save additional pump energy by preventing overflow compared to manually balanced two or three-way controlled coils. Modulating three-way valves can overflow by 40 percent and manually balanced two-way valves can overflow 20 percent to 30 percent when some of the valves are closed or at part load. As a rule of thumb, automatic balancing can save ten percent of the installed BHP when compared to a manually balanced system.
Lower Head Requirements
AutoFlow valves add only 4.6 feet to the calculated pump head. Manual circuit setters typically add ten feet of head (three devices). A five foot lower head requirement can help reduce the size of the pump selected.