Adding main vents, where none exist

Circa1789Steamer

Hello to all those living with steam this winter! I recently bought a 1789 farmhouse with a 1960's era one-pipe steam system and an American Standard Boiler. First things done were insulating the pipes & installing new radiator vents but I still get insane water hammer on the 2nd story far end radiator. That's only part of the issue it seems. It currently has only 2 vents, both on the same end of the main one on the steam main and the other on the very beginning of the condensate return itself. The big steam main, a Dole 3B w/ 5/8th inch thread is clogged to the point of needing replacement, and the second is a smaller Dole 1 w/a 3/8th inch thread. I've also found that though my system has many lovely T pieces down in the basement, there are no other main vents, and only elbows with no plugs, just smooth fittings. So besides replacing my main vents (the radiator vents hiss like crazy when the system kicks on and yes, the cold radiator water-hammers like a tank in the line of fire) I am wondering is it safe/possible to drill and thread new spots for main vents on some of the elbows downstairs, and what would be the best vents to use in this scenario. Even though I cannot replace with new Dole vents, the Dole 1 has a wonderful 90 degree bend to it which would work very well in some places, if there is a similar manufacturer that you folks would recommend. I figured i would get some expert advice, even if that advice includes "yeah, sure you can, but have a pro figure out the where's and what type of vent." Thank you for the help to whomever can offer it. To think, I bought this house because it had "charm" only to find that the definition of the word means "needs constant fixing of archaic technologies.

Abracadabra

Without a layout or schematic of your main piping it's difficult to say if you even need to drill/tap new openings for vents. Replace the vents you have, build a vent station/menorah if needed based on the amount of air you need to vent. Use Gorton #2s and #1s as needed. dump the doles. A Dole #1A is not a main vent, it's a radiator vent.

BobC

How long and what size pipe for each main? A simple sketch would help.

In general to vent the main fast at low pressure consider using a Gorton #2 vent for every 20 foot equivalent of 2" main. Keep the system pressure at 1.5PSI or lower.

Be advised the #2 (1/2" thread) is somewhat large (needs 7+ inches f over head and would like to be mounted on a nipple to get it above the main. Proper venting is the key to good steam system operation. If there is no obvious place to mount a vent you can drill and tap a fitting towards the end of each main or you can have a thread-o let welded onto the pipe.

Bob

nicholas bonham-carter

If the clearance of the dry return, and the ceiling is an issue, the main vents could be tapped into the vertical part of the dry return, as high as possible. Steamhead had a picture of such an installation, but I cannot find it.
It would be best to check your pressure using a low-pressure 0-3 psi gauge, so you can see your pressure in ounces.
Post some pictures of your boiler, and the supply piping, so we can advise about the noise problem. When in good maintenance, these systems should be virtually silent.
Any noise you can hear is wasted energy, and excess fuel cost.--nbc

Circa1789Steamer

I can give good measurements for the length of the piping but the diameter is going to be a bear, as it's now completely (and professionally) wrapped in fiberglass with the exception of the elbows. Most of the piping is pretty massive diameter between 2 and 4 inches until you hit the pipes heading for the individual radiators which are all 2 inch diameter pipes. After reading more through this (way awesome) forum, it seems that I really do need to find a way of adding on some extensions/antlers and fitting either Gorton #1 or #2 main vents onto the system in at least 4 different spots for the house in just the basement alone. The biggest problem is simply going to be how and where as the pipes are all completely assembled and at this point damn near atomically bonded since they've been at one with each other for quite a few decades now. Gotta love New England "charm". Schematics to be posted tomorrow, as at this point if I go clanging about and wake the family, I won't be alive to fix anything come tomorrow!

Circa1789Steamer

Abracadabra said:

Dump the doles. A Dole #1A is not a main vent, it's a radiator vent.

Well at the top of the condensate return, there it sits, with a lovely angled stem, which explains the whole "it's a radiator vent" remark and why I cannot find any type of tiny angled replacement main vent which is similar. Yes I'm a steam system nube, but hey, we all get to be at some point in time. The last time I was near a steam system was huddling up to the cast iron radiators in my grandmothers 1910 home when I was little.. that's about 30 years ago now! If you do have a better suggestion of a better replacement which will thread into there and sits on an angled stem, please point me in the proper direction, as space is limited in that particular spot.

KC_Jones

Checking pipe size. Take a needle or some kind of long thin pointy object and poke it through your insulation until you hit pipe. Measure how much pin it took to hit the pipe, then measure the outside diameter of the insulation. You can then subtract 2x the insulation thickness from your OD measurement. You should then have pipe OD which will give you the pipe size. Hope that helps a little!
Pipe size Actual OD (fractionally rounded)
1" 1 3/8"
1 1/4" 1 5/8"
1 1/2" 1 7/8"
2" 2 3/8"
2 1/2" 2 7/8"
3" 3 1/2"
4" 4 1/2"

Circa1789Steamer

Ok guys. For those of you that asked, here's the schematic for my main pipes downstairs. I'm thinking that I need to put 2 gorton #1's on the right branch of the 4" main, 1 on the left branch and the replace the only busted main vent with 2 number 1 gortons. The other question is how to vent the (extremely long) 2" pipes that head into the crawlspace where headspace between the studs is limited to about 8 inches max. Not really enough room for anything like a #1 or #2. Would a Gorton D vent for a radiator threaded into the farthest elbow work well enough? Any thoughts on this would be very welcome. Hope you can decipher the schematic. Thanks again.

nicholas bonham-carter

You will need one gorton two for each 20 feet of pipe, in your situation. Any extra venting will only improve the performance.
These wonderful old systems need the air let out of all the main pipes first with very low resistance (back-pressure), first, and then the radiator vents with their slightly increased resistance will let the air out of the radiators, and runouts. The result will be the simultaneous arrival of steam at each radiator.
If you scrimp on the main venting, the steam will arrive at closer radiators sooner, and some areas will be roasting, while others freeze.--NBC