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There has been much debate over the years as to whether circuit balancing valves (CBV’s) are required.
I suppose if the piping system was designed to tight tolerances and control valves were sized correctly, then maybe, just maybe, the water would go where it should. The difficulty with that assumption is that during the design process it is hard to take into account the system effect created by the installation. Another significant obstacle is incorrectly sized controls valves.
Circuit balancing valves are used in both heating and chilled water piping, to ensure the correct and/or design flow is distributed throughout the piping system. A common misconception is that CBV’s are sized based on the pipe size, when actually, it is important that they are sized based on the design flow to the equipment served by the CBV. There are also several manufacturers’ of CBV’s, so it is also necessary to refer to the particular manufacturer’s sizing charts.
It is clear to understand why circuit balancing valves are installed in piping that splits to serve the first and second floor of a building. The question is whether they are needed at every terminal unit. The water flow through hydronic coils in air handling units is critical to meet the design performance for heating, cooling and dehumidification, therefore I believe the answer is YES. For terminal units, such as chilled beams, where design flow is critical to prevent condensation, again the answer is YES. But for heating units such as radiant heating panels, unit heaters and entrance heaters with low flow, where the CBV will be open to less than 1 turn of 5, if the fluid medium is not pristine, over time the valve may plug. Without CBV’s on the terminal units some units may receive greater than the design flow and some less. But as the space temperature sensors in the building become satisfied, the control valves will close and the water will be diverted to the areas requiring for heat.
For smaller terminal units, CBV’s may be more of an inconvenience than a necessity. However, for major pieces of equipment (such as chillers, boilers air handling units, etc.) circuit balancing valves are important to ensure there is adequate flow to the equipment. Correctly sizing the associated CBV is crucial. Below are two links to aid with sizing, and if you want to know more about this topic, don’t hesitate to contact us!
For Tour & Andersson CBV sizing, there is app for the iphone at: http://www.tahydronics.com/en/knowledge-tools/hydronic-tools-software/balance-control/hytools/
For the Armstrong CBV sizing: http://www.armstrongpumps.com/Data/pdfbrochures/Links/01_02_005/36.10_CBV_brochure.pdf
Contact CFMS: www.cfms.ca