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Drill and tap for 3/4" pipe.

RICK_64 Member Posts: 20
The main vent on my one pipe/steam system was originally drilled and tapped for

1/2" and uses a 3/4 to 1/2" adapter to accomodate a Gorton vent (possibly a #6 or a

"D" size...). I'm looking to install a Gorton #2 which will require me to open the hole up

to 3/4". Can some one tell me the correct drill bit and tap size needed to do this?

Thanks to all the pros on this site for their insight and info.


  • Dave in QCA
    Dave in QCA Member Posts: 1,776
    edited October 2012

    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
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