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Does It Matter?

Will be piping a TT PS60 in a few weeks piped P/S, got thinkin' if it matters which loop, primary or secondary I place the air sep/ expansion tank on.  The sep is suppose to be where the water is the hottest but, most boiler companies show it in the zone side where the water would be slightly cooler.  Thanks


  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    I'd say

    the system side . With pri-sec , if you install the air separator on the boiler side of the loop , not all the water from the system will pass through the scoop . Air in the system could bypass the scoop while looping through the closely spaced tees .
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    where to put air separator.

    Let me call the loop with the boiler in it the boiler loop, and the other loop the load loop.

    For my W-M Ultra 3 mod|con, all their drawings show the expansion tank and air separator in the load loop. So that is how my system is.

    But I think you are right, that the air separator should be in the boiler loop at the output of the boiler, right after the pressure relief valve. Because that is the hottest part in the piping. I get about 170F water there when the indirect is calling for heat. In the Load loop, the temperature does not exceed 135F and for the largest zone, it does not exceed 120F and is usually under 110F. It takes quite a while for the air separator to get all the air out because the temperature of the water going through it is so low.
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