Book - School of Science and Technology

Water systems ± applications 245Ring mainpumpOversize headerZonebranchesZone mixingvalvesZonepumpsTo zonesFigure 9.8 Header arrangement from ring main to multiple zoneswater quantities circulating in both the zone circuits and the ring main loop were alwaysin correct balance, there would be no need for any enlargement at all!Embedded panel systemsThe particular circumstances which are unique to this type of system simplify the routineof pipe size selection since:. The design temperature drop is usually small with the result that the water quantity incirculation is correspondingly large.. The pressure loss in the heat emitting elements (the pipe coils) is high relative to that inthe main pipework.. The pipe coils are, as a result of care in design, of much the same length and thus carrysimilar water quantities with similar pressure loss.In consequence of these characteristics, such systems are very nearly self-balancing. Indetermining the volume which is to be handled by the circulating pump, note must betaken of both the upward and downward components of emission.Commissioning proceduresThese have been established for many years. The CIBSE Commissioning Codes (A ± Airdistribution, B ± Boiler plant, C ± Automatic controls, R ± Refrigeration systems, W ±Water systems) set down the principles to be followed, including those for proportionalbalance of water systems;applicable to heating, chilled and other closed water recirculatingsystems.Supplementary information is available in the BSRIA Commissioning Guide publications.An integral part of the commissioning process is system flushing, required to removeextraneous material produced during installation. This may require flushing by-passes tobe fitted around components, which otherwise may be affected by unwanted materialdeposits, or at the end of branches to maintain water velocities for successful flushing.BSRIA publications (Application Guide, AGB/91) provide details.