According to Victaulic Regional Manager Marcel Ley, often an unbalanced system is the root of erratic HVAC systems

An effective and efficient HVAC system must provide energy output when required and where required; and proper hydronic balancing is key in ensuring that the system performs efficiently and as intended. Flow in an HVAC system is dynamic, with its performance dependant on various changes such as building occupancy rates, and the demand for heat or cooling.

There are however instances where symptoms of HVAC problems result in temperature variations throughout various sections of a building and are seemingly only brought to surface once tenants complain.

In response to this, occupants often compensate by using space heaters, opening windows and adjusting thermostat settings. Further, additional adjustments to the HVAC system may include larger pumps, resizing components, changing night setback and morning startup times, and flow adjustments in mains, branch lines and circuits independent of the impacts on the entire HVAC system. Most often, these types of “fixes” to alleviate cold and hot zones in a building are typically ineffective and costly and usually do not correct the situation.

With persistent changes to the system settings, building owners are often subjected to higher energy and operating costs as the HVAC systems tend to operate longer than intended, with the system not making use of the energy savings that night setbacks were designed to achieve. Additionally, the operational costs involve additional wear on pumps and HVAC components.

With bthese problems comes the fact that the finger will be pointed at system engineers from the get go, and they will be challenged to defend their design and implementations when in fact the problem lies in the unbalanced nature of the HVAC system.

Indoor temperature and climate problems are not typically caused by control malfunctions or sizing errors. Often they are traceable to incorrect flow rates in the HVAC system due to improper terminal unit balancing.

Generally, engineers design HVAC systems with excess capacity for the buildings which they support, and thus has the ability to provide adequate heat or cooling when necessary. However, many have identified that getting this energy to the terminal and air handling units is the the real problem. We can therefore determine that in most cases the key to HVAC system effectiveness and efficiency is properly controlling flows throughout the entire system from production and delivery units to terminal units for the comfort of all building occupants.

Proper circuit balancing is essential to ensure that the heating and cool water system deliver correct flows to all terminal units in the HVAC system, and most notable, as specified by the system’s design flow.

A tell-tale sign of an unbalanced system will be that sectors of a building will have underflow and overflow conditions that impact control valve authority. This is evident where areas closest to the energy production and delivery source may receive excess flows which result in excessive heat or cooling. Likewise, areas that are further away may experience inadequate heating or cooling levels due to insufficient flow rates.

The typical HVAC system incorporates balancing valves for each terminal unit coil and AHU. In order to balance a coil that makes use of a manual balancing valve, the technician is required to connect a differential pressure gauge or handheld circuit balancing instrument to the valve’s two test ports. Dependant on the valve size, hand wheel position, and the measured differential pressure, the system flow rate through the balancing valve is readily determined with a balancing instrument, balancing flow rate, or the valves determined characteristics. The valve hand wheel is then able to be adjusted to obtain the required system flow rate.

Applying this technique to each balancing valve throughout the system will result in proper balance being achieved. When pumps, chillers, and other components operate at the lowest possible load, the benefits obtained from lower wear and tear costs, longer equipment service life, savings in maintenance and energy costs; and happy tenants would bear testament as to how preventative maintenance and correct procedures are essential in HVAC operations.