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fuel tubing size

chuck172chuck172 Member Posts: 90
On a one pipe oil pipe system, what is the normal soft copper size, 3/8" or 1/2" OD?
This is from the duplex fitting on an outdoor 275 gallon tank to the in the basement tigerloop at the burner.


  • STEVEusaPASTEVEusaPA Member Posts: 4,206
    How far from the tank?
    How tall is the tank?
    How much total rise (and fall)?
    Which fuel pump are you hooking into?
    If it's all within the usual tolerances, 3/8 is probably fine, it's even better then 1/2".
    Just remember if the drop is too much (>3psi) you're going to need an oil safety valve before the tiger loop/firomatic at the burner.
  • chuck172chuck172 Member Posts: 90
    The drop is 5' from the tank to the burner. I think an osd makes sense to prevent syphoning of the tank, many so that they are not necessary, more of a pita than beneficial.
    Anyway, shouldn't they be piped after the filter just before the oil pump?
  • chuck172chuck172 Member Posts: 90
    sorry, I meant OSV, not osd.
  • STEVEusaPASTEVEusaPA Member Posts: 4,206
    edited May 2016
    I didn't work my last post correctly. Yes after the filter, but-

    Caution--Do not mount the OSV more than three feet above the burner fuel pump inlet, or more than three feet above the lowest point in the fuel line connecting the OSV to the burner fuel pump...
  • captaincocaptainco Member Posts: 451
    I could never figure out why the OSV is between the filter and the pump. I would think a leak might occur somewhere before that or at least before the filter.
  • STEVEusaPASTEVEusaPA Member Posts: 4,206
    They claim if before the filter debris could keep it stuck open (which I know you know very well). But the filter, fittings & tank shut off are all good (?) leak candidates.
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