With P/S piping, the ability to isolate system circuits makes it relatively easy to design sophisticated multi-load systems without concern over how flow rates and pressure drops will change as various circulators turn on and off, Siegenthaler says. Whether a parallel primary loop is built on site, or the function is performed with a purchased, preassembled low-loss header, it's the closely spaced tees - or their equivalent, closely spaced ports - that allow each circuit to function as a singular circuit with no real connection to other circuits. This detail "uncouples" the primary and secondary circuits, allowing several circulators of different pumping abilities to "coexist" within the same system without interfering with one another.
He adds that the essential design detail has always been a pair of closely spaced tees that couple each secondary circuit to a common primary. Hydronics expert John Siegenthaler says that primary/secondary piping has been used in the hydronic heating industry for decades. Some, however, caution against overusing low-loss headers. Many regard the installation of a parallel primary loop or low-loss header as fundamental to the optimal performance of low-temperature, multi-zone hydronic systems of almost any size or configuration. Their purpose is to connect the secondary circuit to the primary loop in such a way that neutralizes any tendency to influence flow in the secondary circuit. The key detail is a pair of closely spaced tees or a hydraulic separator between the boiler or heat source and the load circuits. Low-loss hydronic headers are available from Caleffi, Viessmann and Buderus in pre-assembled packages that perform the function of a parallel primary loop. My new, improved hydronic heating system includes several Grundfos three-speed SuperBrute circulators, a selection of Watts Radiant gear, a Lochinvar Knight wall-hung condensing boiler and a Caleffi HydroLink low-loss header. Probably more, especially considering the volatility of copper costs! The approximate cost? I figure $ 1,000 to $ 1,500. elbows air purger unistrut channel unistrut clamps loop hangers miscellaneous fasteners solder and flux and the time to design, cut and torch the loop and assemble all the components. What lay in ruins on my porch floor was this: 10 ft. Why not inventory what's here, and estimate the time it takes me to design and construct what a pre-assembled low-loss header provides? I had ripped out the system's primary loop, and the tangle of copper thrown on my porch - with many of the parts still intact - hinted at the complexity of the primary/secondary piping arrangement that I was replacing.Īs I wrangled that piping network from my mechanical room wall, an idea struck me.
Just before this heating season's first cold front closed in around our home in southwestern Missouri, I was in the midst of a hydronic overhaul only the radiant loops would stay. Modern high-head condensing boilers pretty much dictate their need and use. ALTHOUGH I ENJOY working with copper pipe, and I really like a good design challenge, I've come to the conclusion that a wellengineered low-loss header, out of the box, makes a lot of sense.
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