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NORA Advanced Hydronics

The one pipe (Figure 3) system utilizes one main pipe that connects from the boiler supply to the boiler return. The heat emitter is connected to the main by two smaller (feed and return) pipes that are fitted with diverter (aka Mono-flow, Venturi, Jet, or One pipe) tees that cause a portion of the water circulating in the main to be routed through each section of the attached emitters. Typically, one standard tee and one diverter tee are used for each emitter unit. It is important to follow the manufacturer’s instructions regarding the spacing between the tees and which pipe (feed or return) to install the diverter tee on. Sometimes it is necessary to provide two mono-flow tees for a single heat emitter to produce sufficient water flow through that radiation. For example, if a radiator is lower than the main pipe, the buoyancy effect of the cold water at the bottom and hot water at the top will cause insufficient flow. In this situation, two diverter tees must be used and the spacing between them should be the same as the width of the heat emitter. Figure 4. Another situation where two diverter tees may be needed is when a radiator has been removed and replaced with baseboard heating. In those situations, the diverter tees can be relocated to compensate for the additional pressure drop through the baseboard or an additional diverter tee can replace the standard tee. Figure 5 on following page. 16 National Oilheat Research Alliance Figure 4 Figure 3


NORA Advanced Hydronics
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