HEATING AND COOLING SYSTEMS CIRCUIT BALANCING
FLOWINGHOT & COLD A
Many building managers would agree that the symptoms of indoor climate problems most often surface as complaints from tenants. Living or working spaces are too cold in winter, too hot in summer or a combination of both extremes. David L Hudson, senior product engineer at Victaulic, explains how circuit balancing can help minimise the gripes
ll too frequently, ‘fi xes’ to heating, ventilating and air conditioning (HVAC) systems prove both costly
and ineffective. Costs may include the installation of larger pumps, the resizing of components, the changing of night- setback and morning startup times, and fl ow adjustments in mains, branch lines and circuits. For example, the resetting of a workplace HVAC system startup time from 7.30am to 5.30am leads to a plant operating at capacity two additional hours per day. This equates to a 25% increase in energy consumption, cancelling any energy savings that night setbacks are designed to achieve.
Additional consequences include increased wear on pumps and HVAC components, and reduced control-valve authority. Indoor temperature and climate problems are not typically caused by control malfunctions or sizing errors. Often, they can be traced to incorrect fl ow rates attributable to improper terminal- unit balancing. Engineers normally design HVAC systems with excess capacity in mind, so that the ability to provide necessary heating or cooling energy is present. Transferring that energy to terminal units and air-handling units (AHUs) is the challenge. Therefore, the key to HVAC-system effectiveness and effi ciency is properly controlled fl ows from production and delivery units to terminals.
Balancing fl ow for comfort and control Balancing valves maintain fl ow conditions so that control valves can function properly, providing correct fl ows to the heat transfer coils, which results in the correct output of energy to a space.
www.cibsejournal.com
February 2013 CIBSE Journal 49
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