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Main Vent Tapping Ideas

I think our longest loop main (cloverleaf layout with 3 main loops across the whole basement that lead to radiator risers) could use a few more Gorton #2 vents. It's about 75 feet long from boiler until last radiator with 20 feet of 3.5 inch & 55 of 2 inch pipe. We have one 1/2 inch tapping so far with 3 vents on it. Would you reccomend tapping another one or two 1/2 inch holes in the main and adding 2 Gortons max per tapping to max out the 1/2 air flow, or try and increase the size of the current tapping and make an antler to hold 4 -6 Gortons from a single large tapping? Our 2 inch main the becomes 1.25 inch dry condensate return just after that last radiator for another 25 feet before returning into the boiler room.


    JUGHNE Member Posts: 9,765
    A 1/4" tap will handle a G-2 very well. (Actually a 1/8" pipe will pass enough air, but if you look at the inside diameter you can see it would not take much junk to plug it up) This is how I did end of main venting on a system that had no vents or open ports available. These were drilled and tapped for 1/4" IPS. IMO a 1/2" tap in a 1 1/4" pipe does not give you a lot of meat for strength. In my mind it is the ratio of hole in pipe to circumference of pipe. I added a strainer for each as this was a 90 year old system that had a bad life in the last 25 years or so. Strainer is 10% of cost of a G-2 and I figure cheap insurance. The extra support hardware is there as there is considerable weight put upon the 1/4 tap. This also assures the slope of the horizontal vent assembly to drain back to the main. imageimageimage
  • BobC
    BobC Member Posts: 5,309
    If you can break the 1.25 dry return and mount your venting tree there it could support 12 gorton #2's. By my calculation a 1/2" pipe has an area of 0.196 sq in while the 1.25" has 1.23 sq in.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
    JUGHNE Member Posts: 9,765
    edited January 2016
    Yes, that would be a great option IF there was a union there or user friendly threaded fittings. If that was an option I would go for the 1" tee tapping. (about 5 G-2 vents) I have noticed that original steam systems installers seldom installed unions or flange connections. (They were more confident in their pipe fitting methods than I am of my own :'( , I will put in quite a few unions as I put threaded pipe together, I always keep in mind how much piping I would have to take apart if needed for whatever reason.) I have worked on a lot of NG piping where the only shut off is in the alley at the meter and the only unions are at the furnace and water heater valves. (they considered the gas valve itself as the service valve for the appliance....1960's.).
  • cubicacres
    cubicacres Member Posts: 355
    Thanks-we can uncover the pipe when we're ready to add the tappings and see what we have under the insulation.
  • cubicacres
    cubicacres Member Posts: 355
    Good news-we found a union just past the 1/2 inch tapping on the 1.25 inch dry return pipe-see photo.

    We're thinking about reducing one Gorton #2 from the 1/2 inch pipe shown on the left in the photo to make it 2 to max out, then adding 4 Gorton #2s to another antler facing the other direction with the 1.25 inch Ts & couplers down to 1/2inch to set each Gorton in. We can always add more than 4 Gorton #2s if needed later. That long loop has more radiators, is 20 feet longer, smaller 2in vs 3.5 in diameter, and goes through colder crawl-spaces compared to the middle & short loops, so I think we'll need to seriously over-vent this loop to balance things out. We can even consider reducing the short & medium loop venting a bit if needed to favor the long loop. Any other ideas on helping a long, slow, cold, heavy radiator-line get faster steam through it?