In Fall 2015 I installed 5 vertical loops to a depth of 150 feet. These loops support 2 - 3-ton geo units. I think that the loops were connected in parallel, a single manifold box distributing to all of the loops. It seems to me that the flow following the path of least resistance could result in a preferred loop taking most of the flow. I read a report that seemed to indicate that this was industry standard. Is it standard? Why would a parallel loop system be used over connection in series? Bill B
Yes, it is standard to install the loops in parallel vs. series. The reason is flow resistance and resulting pressure drop in a series circuit. Also, you want the flow high enough to maintain turbulent flow for increased heat transfer (Reynolds number >2500). With a parallel loop connection you can maintain adequate flow for turbulence and yet still have sufficiently low flow resistance for ease of pumping and lower electrical consumption. Parallel circuits typically use a reverse return header with roughly equal length loops to better balance flow between the loops.
OK, thanks. Forty years out from hydraulics courses, this makes sense. Reverse return header means that the loops are connected to the in and out headers in reverse Order? I didn't watch the installer that closely.
