HYDRAULIC SEPARATORS
CALEFFI HYDRAULIC SEPARATORS KEEP PRIMARY AND SECONDARY CIRCUITS CONNECTED HYDRAULICALLY YET ABLE TO FUNCTION INDEPENDENTLY FROM EACH OTHER, SAYS ALTECNIC COUNTY MANAGER FOR IRELAND, CHRIS REILLY... Finding the right separator for your project
M any hydronic systems use compact boilers as their heat source, with these boilers offering much higher flow resistance than cast iron boilers. If such a boiler is simply substituted for a low flow resistance boiler, problems are likely to develop, most notably interference between simultaneously operating pumps. The designer of such a system might assume that each zone circuit develops a flow based on the flow resistance of its piping and the circulation pump in that circuit. In essence, this thinking treats each zone circuit as if it was a stand-alone circuit, unaffected by its neighbouring circuits. This oversimplification ignores the fact that the total flow of all zone circuits must pass through the high resistance heat source. The latter will act as a flow bottleneck and significantly reduce the flow within each zone circuit. The more zone circuits that operate at one time, the worse the bottlenecking effect. The resulting drop in flow through individual zone circuits may create underheating, which will likely lead to complaints of inadequate heat delivery in some zones. To solve this issue, a designer should opt for hydraulic separation. When hydraulic separation between circuits is present, the designer can correctly think of each
circuit as if it were a stand-alone entity and design it accordingly. This not only simplifies system analysis, but also prevents the previously described flow interference problems. HYDRAULIC SEPARATION AND OPERATING PRINCIPLES When a single system contains a primary production circuit with its own pump/ pumps, and a secondary user circuit with one or more distribution pumps, operating conditions may arise in the system whereby the pumps interact, creating abnormal variations in circuit flow rates and pressures. The hydraulic separator creates a zone with low head loss, which enables the primary and secondary circuits connected to it to be hydraulically independent of each other. The flow in one circuit does not create a flow in the other if the head loss in the common
section is negligible. In this case, the flow rate in the respective circuits depends exclusively on the flow rate characteristics of the pumps, preventing reciprocal influence caused by their connection in series. Therefore, using a device with these characteristics means that the flow in the secondary circuit only circulates when the relevant pump is on, permitting the system to meet the specific load requirements at that time. When the secondary pump is off, there is no circulation in the secondary circuit; the whole flow rate produced by the primary pump is by-passed through the separator. With a hydraulic separator, it is therefore possible to have a production circuit with a constant flow rate and a distribution circuit with a variable flow rate. Such operating conditions are typical of modern heating and air-conditioning systems. Possible hydraulic balance scenarios...
“Three-in-one hydraulic separators make air removal and dirt removal primary functions.”
74 | PLUMBING & HEATING MAGAZINE
FOLLOW US ON:
www.plumbingmag.com
Made with FlippingBook - professional solution for displaying marketing and sales documents online