Main Vent Advice

Ralph Blaine

I have a one pipe system that has no air release valves on the mains. This forum has helped me in the past to find the proper valves for the rads themselves and there was a big improvement. Now I'd like to work on the mains. I have seen Steamhead offer to advise on the size of valves required when dimensions are given. Could you please advise for the three lines below. Any help much appreciated. I have already purchased two Hoffman 4A's so it would be nice if I could fit them in somewhere as I've got about $80 (Canadian) tied up in them.


1. Line #1

This line has a run of 27 feet (insulation is 3.5 inch rolled asbestos cardboard) and feeds two rads on first floor at end of this run before rising up to second floor (12 feet) on a 1 3/4 inch OD iron pipe. Due to the asbestos I don't see any way of tapping into this main but it might be able to put vents on top of the riser. What main venting would this require.

2. Line #2

This line has a run of 20 feet in 1 5/16 OD iron pipe . There is a right angle at this point with a plug which could be removed for a vent. The line then continues with 1 1/8 copper OD pipe for 22 feet . Could I put one vent at the plug and another at the end of the line?

3. Line #3

This line runs 17 feet with 4 inch insulation (asbestos cardboard) when it hits a T joint - going down to a condensate return and up about 22 feet (2 inch OD iron pipe) to feed rads on the third floor. I could tap into the T joint to add a vent or I might be able to put a vent at the top of the riser. See diagram below. I don't really understand all this piping. It looks a bit like a false water line in Dan's book but both lines at the top of the diagram go all the way to the third floor. I loose track of them after they move out of the basement as they are hidden in the walls and floors.

Steamhead

Answers

1. Two Gorton #D vents near the top of the riser. Drill and tap for 1/8" pipe thread for each.

2. Two Gorton #1 vents at the end of the copper. You really should replace that copper with black steel. Those sweat joints don't hold up well on steam, though they're fine for water-filled return lines. Don't use the plug- you want all your venting capacity at the end of the main.

3. Gorton #2 at top of 22-foot riser, unless you find that 2-inch pipe turns horizontal at the third floor level, runs for a while and drops to the condensate return. In that case, put the vent as high on the return as you can.

You might consider trying to sell the 4A vents on ebay or something similar. Thay're really too small for your system.

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Ralph Blaine

Thanks, Steamhead for the prompt reply. In regards to the third line.

Yes the steam does come up to the third floor, feeds a radiator right at the top and then runs horizontally across the length of the house (maybe 40 ft or so) to feed three more radiators. So maybe it does drop into that condensate line that runs up along side as shown in my diagram. The problem is that I can't get at the condensate line except in the basement (where the Gorton valve is shown in the diagram) and in a closet on the second floor. So if I use the line in the closet do I understand that the valve should be tapped into the condensate line? Would this line in the closet on the second floor be OK ? Can I drill right into the pipe of the condensate line and tap this hole?

Alternatively, can I simply use the spot already tapped in the basement which now has a simple radiator valve on it as shown in the diagram?

Once again, thanks for your help.

Steamhead

You could put the vent in the basement

but it's a waste of steam to heat all that return piping. So I'd put the Gorton #2 in the second floor closet. It should be installed on 1/2" piping. Leave enough room to add a second #2 if this part of the system still heats slowly. Remove the vent in the basement part of the condensate line and plug the opening.

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Ralph Blaine

OK, I think I've got it now. I'm going to drill and tap a half inch hole right into the condensate line in the closet and attach a #2 Gorton and then plug the hole in the basement. This line has some banging on start-up. I wonder if that undersized Gorton in the basement (which is old and may not be working) is part of the problem? Does the Gorton #1 also need a half inch opening? Thanks for your advice.