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DWV for near boiler piping

mjstraw
mjstraw Member Posts: 41
edited October 2021 in THE MAIN WALL
Mid-70's(?) Burnham Holiday boiler feeding gravity conversion system with 2.5in mains. While draining my compression tank the other day, I got studying the near-boiler piping with an eye towards redoing some things (pumping away, adding a zone).

Even though the boiler tappings are 1.25in, they used 1.5in to tie it into the mains.  I was surprised to discover a faint "DWV" printed on yellow on one piece.

My guess is it was cheaper than 1.25 L or M, or they couldn't get 1.25in, or the DWV is what they had in the truck.  The fittings look like brass DWV fittings, too.

No problems, just curious.

Mark
Indiana PA

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 25,267
    Well, they probably shouldn't have, but for a heating system it's probably fine.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Solid_Fuel_Man
  • JUGHNE
    JUGHNE Member Posts: 11,311
    They may have had overstock of copper DWV piping, it may have been going out of fashion as PVC came in or it was cheaper than type M at that time.

    As Jamie said probably not not to worry about not running very little pressure.
    You might notice that the bury of the copper into DWV fittings is only about 1/2 of regular fittings. Not to worry about that either as I have seen some DWV fittings on water supply at 40 PSI with 50/50 solder (not that strong)....still holding after 50 years.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,850
    What @Jamie Hall said

    I have seen this done many times without issue.

    It proves it was installed by a plumber

    I don't know the difference between DWV and "M" tubing (as far as wall thickness goes) which is commonly used in heating systems except the DWV fittings have less socket depth. I am sure it will hold 30psi
    JohnNY
  • mattmia2
    mattmia2 Member Posts: 11,149
    I suspect the sweep of the bends is longer on the DWV fittings.
  • mjstraw
    mjstraw Member Posts: 41
    Looks like shallow socket but not long sweep.

    Mark
    Indiana PA

  • mattmia2
    mattmia2 Member Posts: 11,149
    edited October 2021
    I think the sweep is a little bit longer than a pressure fitting but not much. The hub is usually almost touching on a pressure fitting. There is a long sweep 90 that is much longer.

    https://www.supplyhouse.com/Elkhart-31322-2-Copper-90-Elbow
  • JUGHNE
    JUGHNE Member Posts: 11,311
    To me, they look to match the pattern of PVC DWV fittings.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,850
    And if u check a “90” with a square you will find out they are not square they are pitched 1/4”/foot

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