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Expanion rate

What is the expansion of the copper lines in a horizontal run 100' long, of 1 5/8" copper discharge line and 1 1/8 liquid line? In inches, please. Ok ,I'll settle for the expansion rate if need be.


  • Jamie HallJamie Hall Member Posts: 6,010
    very nearly

    10 microinches per inch per degree F temperature change.  Depends a little on the alloy.  

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • meplumbermeplumber Member Posts: 678
    Rule of thumb.

    Terry, the rule of thumb that we have been using for AC and Refrigeration is 1" per 100' of horizontal run, properly supported.  It isn't as exact as Jamie's number, but hasn't bitten me in the rear yet.  I will do an expansion loop only if the horizontal run exceeds 150' and it is a heat pump application.  In AC only, the temp rise is below the point where it will cause a sufficient expansion to stress the joint.

    Good Luck.
  • TechmanTechman Member Posts: 2,141

    Thanks Jamie, using your formula, I was closing in on that 1" # that meplumber provided.  Yup ,pretty darn close.  
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