Gravity Conversion Pri/Sec Pumping Circulator Sizing

Peter_26

<span style="font-size:12pt">Good day to all,</span>

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<span style="font-size:12pt">Our old gravity fed system was converted to gas and forced circulation some time ago, but there is no bypass pumping in the system. Our plumber had told us some time ago to convert to primary/secondary pumping and had given us a sketch of how the system would look. I was curious and wanted to be an informed consumer, so I bought Dan Holohan's set of books which include "Primary Secondary Pumping made Easy", "How Come", "Pumping Away" and another book, which I can't seem to find. In one of the books Dan states that for a gravity conversion you want the high GPM because there is little resistance in the piping because it's so large and the system has a lot more water. OK, in the sketch he has 1 TACO 007-F5 for the primary and a B&G Series 100 for the secondary. The Series 100 is very expensive, compared to the 007 and I looked at both curves and the Series 100 has more flow @ 3.GPM, about 27GPM versus 18GPM for the 007. I don't know if that's overkill and the price is very high and I asked the plumber why couldn't we just go with 2 007's, one for primary and one for secondary. I was also reading somewhere on the wall about not wanting the flow to be too fast also because of thermal shock. Any advice would be greatly appreciated.</span>

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<span style="font-size:12pt">Thanks,</span>

<span style="font-size:12pt">Pete</span>