Old Gravity HW Piping

Al Letellier_9

CC, if you're already doing P/S on conversions, you're heading up the right road. We always do it that way, with constant circulation and outdoor reset. It give you the most operationg efficiency while keeping the comfort level the same...the rads are always warm. Same rules apply as with FHW as to sizing your crossovers and P/S sizes. It usually takes a normal size pump on the primary as piping is large and has little head.Just make sure you move enough water to meet the demand and you've got it.

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Climate Creator

Piping Correctly

I see so many of these old gravity systems that have been converted to FHW some time ago and most of the time the installers seem to do as little re-piping as needed and some tie all the lines together with varying methods. Are there any hard and fast rules to re-piping these mega-gallon systems? Should separate returns and supplies be tied together(header)? Are there any rules of thumb that determine the correct pipe sizing for the ties? Any rules on where to bring in the circ? I already pipe these systems P/S but I have a feeling that I could be doing more, dont get me wrong the systems work, but how are they most effeciently piped? So many clients think that just replacing the unit is efficient enough, but more is involved, I would just like to be in the know, instead of the,"we always did it this way" crowd.

Thanks in advance,

Merry Christmas, (Happy Holidays is now offending me)

CC

Climate Creator

Thanks, But...........

I really do appreciate the reply, but I was wondering about the connecting of say two separate supplys that at one time had two different places to go on the old boilers and were just teed together. I seem to remember something about using 4 pipe sizes smaller or something as a rule say for a 2 inch main I would connect the circs using 3/4inch to the header injecting from the boiler loop into the teed supply main, if there are no monoflow tees to set direction should a check be added to direct flow? Also should a constant loop circ be put into the former gravity loop and allowed to just circulate and use another pump to inject to that loop? So many things, so little energy,

Thanks in advance,

CC

brucewo1b

http://www.heatinghelp.com/heating_howcome1.cfm have you read this page yet its worth a read on Gravity Systems