Double “loop” return

WigglyWalker

I’m replacing this beauty and I haven’t seen return piping like this, this is a one pipe system with three separate take offs, 2 loop around the basement supplying the radiators and return with air vents at the end.  The third is off the main with the return coming back just before the equalizer. The first Hartford loop is above the water line and then it goes into another attempt of a Hartford loop which is below that water line. Before I change it to what I believe makes sense I wanted to see if anyone thinks this was done for a reason and I’m overlooking it’s purpose. 

Jamie Hall

I presume that second Hartford Loop is hiding behind the flue?

At a guess, I'd say someone replaced the boiler at some point and rather than trying to get the new water line at the same elevation as the old one (which they should have done) just plunked the boiler on the floor and left. And didn't reroute the old higher Hartford Loop. No harm. In fact, the old Hartford Loop may be acting as a false higher water line and preventing obscure problems out in the rest of the system. I'd leave it be.