Parallel primary loop?

subcooler

Timco

I have a conv gravity system I am replacing, and it has three zones out from the boiler room. Since all zones are the same heat demand, would a parallel primary system using crossover bridges be better suited? With the primary loop @ 5gpm, how is the balancing valve (flow rate) figured for the crossover bridge?

Thanks, Tim

Timco

Is there not much benifit to using this piping method vs. regular p/s?

Tim

siggy

parallel primary loops

Tim,

My opinion on parallel primary loops has changed in the last couple of years. You can achieve the same benefits (equal supply water temperature and hydraulic separation) with a hydraulic separator, and eliminate the need for a primary circulator. Sample drawing attached. See the Hydronics Workshop column in the upcoming November issue of PM for more details.

Siggy

Ted_9

HC

Hydraulic Separators, they are neat.

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S Ebels

Siggy

Isn't the boiler circ in your drawing in effect becoming the "primary circ"? So really you're making the circ serve a dual purpose?

PS: I agree on the LLH/hydraulic sep concept. Much easier and less piping than two pipe pri/sec. Wonder where that idea came from?

mp1969

Whose brand of hydraulic seperator do you recommend??? A very new concept to me. But I am willing to learn.

MP1969

Ted_9

HC

Two that come to mind are Caleffi and Viessmann.

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Timco

This is a very new concept to me as well...was going to just go p/s, but thought the parallel primary loop looked like a interesting option. When one CI boiler is used, and all 3 zones want equal heat, is there a need to go p/s or would 2-pipe direct return w/ boiler bypass be the ticket? Am planning on seperate circs for the zones, not zv's. Piping is a small loop, not large enough to need reverse return.

Thanks a million,

Tim