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Why is a purge assembly never shown on manufacturer's piping diagrams?

Alan (California Radiant) Forbes
Alan (California Radiant) Forbes Member Posts: 4,055
edited June 2020 in THE MAIN WALL
It's such an easy thing to pipe and definitely THE easiest way to purge air.

This is only one manufacturer, but they all seem to leave it out.

8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab


  • dopey27177
    dopey27177 Member Posts: 887
    Sometimes you need to deeper into the product. Not the circulars or adds,

  • hot_rod
    hot_rod Member Posts: 22,266
    if there is a circ inside the boiler, pumping into the boiler, I would rather see the check on the supply to the closely spaced tees. Not ideal having a check on the inlet side of a circulator.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • jumper
    jumper Member Posts: 2,289
    Best is old style expansion tank at high point. Pressure created by gravity rather than compressed gas. Where does air continuously come from and where does water go to?
  • rick in Alaska
    rick in Alaska Member Posts: 1,457
    I'll answer your question. Because I think Dan must have patented it! Seriously, since reading his book, I have piped every one of my jobs the way you have it sketched out. More or less anyway, but mostly this way. I like to have the ability to be able to push every bit of the air out from one location, and to not have multiple purge valves all over the place if I don;t have to.
    Alan (California Radiant) Forbes