Balancing valves are devices which moderates and controls the flow of water/fluid and balances heat and cooling distribution to several locations. The primary purpose of these valves is to facilitate the precise quantity of heat and cooling to each part of the building. Heating or cooling water distribution system is in balance when the complete flow in the entire system equates to the rate of flow which were pre-defined for the specific design of the system. These valve systems are specifically fabricated to render a superior level of thermal comfort, have reduced energy consumption and should give the rate of flow as meant. The flow control and balancing valves render precise distribution of water flow surrounded by the hydronic system to cope up with the demands. Every engineer, while taking into account the hydronic system which feeds the air terminal coils for zone control, has to pick amongst an automatic flow controls or manually balanced system. Also, there is a considerable energy saving and performance benefits to rationalize a system having automatic flow controls.
The manual balancing valve (MBV) should render an exclusive amalgamation of two functions to the hydronic system – the capability to measure the resultant flow, and the capability to choose the stifle flow to a branch circuit or terminal device. These valves function along with a fixed, though manually adjustable resistance. The flow of the fluid via manual balancing valve depends upon the degree to which it is confined and the differential pressure positioned across it. Several manual valves available presently comprises of a valve along with a placed indicator. This position is later equated to a chart to examine flow coefficient (CV)’s value and the rate of flow is ascertained depending upon this value. The manual balancing valves do give an ability to balance the complete system. They experience usage difficulty and more than required system pressure drops.
Even though manual balancing valves function quite efficiently and do the desired task as required, they do have certain drawbacks, one being that manual balancing valves are pressure dependent and therefore do not mend to altering system pressure. A few of the other shortcomings of the manual balancing valves are –
•The concrete flow of water would differ as the system pressure dissents thereby generating necessary unbalanced system.
•The system balancing usually needs a balancer to make a minimum of three adjustments to every manual balancing valve.
•Anytime the hydronic system is reconfigured, there is a requirement of system rebalancing.
•When manual valves are put to use on the air terminals, supplementary valves would be needed on the riser as well.
•Every few years, a few municipal energy codes need systems to be recommissioned.
•During the balancing phase of the project, the control designed water, flow simply at the pressure.
Manual balancing valves are separated into two types based on their method of measuring flow. There are variable-orifice MBVs and fixed-orifice-type MBVs. The variable-orifice manual balancing valve (VOMBV) determines the pressure drop all over the confined valve. The fluid flow is measured by examining the pressure drop over the resistance that gets formed in-between the plug and the valve seat, just when the VOMBV balancing valve is confined. On the other hand, the fixed-orifice MBV (FOMBV) disintegrates the measuring and confined functions. Generally, the throttling is carried with a ball valve and the measuring is accomplished with either an orifice or a venture plate.