I need some expert advice

bt_h2o

I need to eliminate supply & return mains in basement to allow for headroom as part of a remodel. Mains are 2" with 1 1/2 & 1 1/4 branches to cast iron radiators on 3 floors. System was originally gravity hot water. Boiler was replaced(Nat. draft chimney vented boiler) I would say within last 10 years with addition of circ. pump on return side. Any advice on how I could repipe system in basement to maximize headroom and still allow for equal/sufficient heat to all radiators on all floors? I was thinking monoflo loop in basement with pex runs reconnecting to existing 1 1/2 & 1 1/4 drops. Any thoughts or recommendations would be greatly appreciated. Thanks

hws

resize

If the system is no longer gravity-feed then you probably don't need such large pipe sizes. Do a heat loss calc, then punch the numbers into the universal hydronics formula, to see what pipe sizes you need.

furnacefigher15

zoning

I would take the opportunity to zone the system. If you are re piping anyway, you might as well improve comfort while you are at it. You need to size the piping large enough to handle the existing boiler, if zoning, the zones need to be large enough to handle the connected radiation, or % of load.



It should be fairly simple to figure out what goes to the first floor, b/c there will be a corresponding radiator.



I would run each zone circuit in parallel reverse return. (first to get supply, gets return last and vice versa)