Which Hydronic Supply/Return Lines to use? Copper/Pex-Al/? (150-160 degree water)

jb_14

Old house with new addition and new hydronic under floor radiant system.  Need to take supply/return lines to a zone of hot water baseboard/runtal type radiators to rooms that are not accessible for pex/plate under floor radiant that's going in rest of house where joist bays are available.  I have a 'chase' where some flexible piping would do wonders to get me up to the 2nd floor, pop out of the wall and supply the baseboard.  This will be my highest temp heating zone - probably 150-160 at design conditions (Wash DC area) but probably modulated down much of the time.  Trying to use my condensing boiler to its fullest - so not planning any 180 degree zones (except indirect hot water).



So - I was thinking of using 3/4" type L soft copper that I can snake up from the basement to the 2nd floor through this chase.  (all supply/returns were planned to be copper). Then I thought - why not pex for the supply/return lines also?  I've got hePex in all the floor loops.  So maybe pex-al-pex for supply/returns (slightly better pressure ratings at high temps.)



Or - what about those pre-insulated flex stainless line sets I've seen for solar thermal?



Will Pex Al Pex be good for decades at 150 degrees every winter?



Also this 'chase' is in an exterior wall.  I will insulate the supply/returns directly and then fill the vertical chase with cellulose from hole in siding above.



Any thoughts on these random thoughts?  Stay with thick walled copper for supply and return lines - or go pex all the way?



I'd need to use compression fittings - or invest in the Viega or Uponor press systems.



Sorry to long.  Thanks!

JB

Al Letellier_21

PEX piping

The only disadvantage to using PEX is if it ever does freeze, you need direct access to the pipe to thaw. With copper you can use a thawing machine, But in your area, with well insulated chase, I would use the PEX-AL-PEX to save time and money