gravity converstion

Dan_18

On page 28 of How come Dan talks about putting the existing supply and return together to form a system loop. Can some one show me a diagram of how this is done with lets say two supplys and two returns? Thanks in advance.

Dan_18

Some one....any one.. I guess the main reason I asked this question is because im worried about reversing the flow in the mains and by the way I understand it I would connect the two returns together then connect the two supplys together. The boiler and primary circ would attach on the new piping on the supply with two closly spaced t's. Just after the boiler would be the system circ. Is this correct?

Mike T., Swampeast MO

Yes, you bring the two supplies together with piping based on the "½ the largest size minus one further pipe size" rule. e.g. 3" mains means 1¼" new common piping. The supply pipes are the ones exiting from the top of the boiler.

Do the same with the return pairs. Depending on the old boiler it's rather common for the return pairs to already be brought together into a single and enormous (4" or so) pipe leading to the bottom of the boiler HX. In this case, you need to take out that huge common piping and bring the returns together as mentioned above.

Your circulator placement/piping sounds dead-on correct.

Dan_18

Thank you Mike! So just to clear it up the mains become one long loop now that the old near boiler returns are joined together right?

Mike T., Swampeast MO

The main pairs don't really become a loop. More like a big, long, mainfold that diminishes to both ends with the feed (or return) in the middle.

Have seen them brought together with tees in "bullhead" fashion as well as one fed by branch of a tee and the other by the leg. Both seem to work OK.