end of main vents

moneypitfeeder

I was hoping someone could give me some suggestions on how to "gently" remove an end of main steam vent. I'm trying to take them off and clean them, and evaluate if they need rebuilt or replaced. (One hisses shortly after the boiler kicks on and seems to be venting, and the other main line vent has never made a peep) They are both not wanting to budge. I don't want to spray with wd-40 or silicone if it will seep in and contaminate the inside of the steam main, and I don't want to break the really rusty fitting below them, but I'm having problems getting heat from the main that the vent isn't venting. Any tips out there other than a big cheater bar (which I've been using!!)?

Thanks,

Dee

BobC

Stuck

If the vent screws into a female coupling on the end of a pipe nipple, try heating that coupling up with a torch. You will have to hold the torch on the fitting for a while to get it good and hot, be careful of any wood nearby. That heating should cause the fitting to expand and loosen the corrosion holding the vent fast.



When you get it off and cleaned use some teflon tape to make it easy to get it off the next time.



Bob

haaljo

remove vents as if you are replacing.

Worst that can happen is you get a couple of #2's for about $50 each. i have had good luck on ebay. Might actually be the best that can happen for you. Happy Thanksgiving

moneypitfeeder

Thanks!

I'll give the torch a shot, and if it still doesn't want to budge, I'll order new to have on hand and then do what ever is needed to remove it, Thanks for the advice!

moneypitfeeder

Okay, removed the vent, but....

Hi guys, got the vent removed, sort of. The pipe that is threaded into the the main that the vent is threaded on to turned out. Got the thing out in the open, tried to heat up the vent to open it up, no dice. I was able to flush a little bit of black gunk from the vent via the pipe still threaded onto it, not much else. I'm guessing I'll have to get a new one, but I'm having a hard time finding any specs on what replacement I should get. Its a JAS. P. Marsh No. 5 Thermodisk, made in Chicago. They are located at the very end of both of my mains, and directly under them are dry returns that drop down to the basement floor and back to the boiler return piping. So that all leads to another question. The dry return lines both get as hot as my mains are, basically the mains die at a tee, to the top is the vent, bottom is the return. Should those returns be getting that hot?

Thanks, Dee

BobC

Right vent

Your saying the pipe the main vent is on came out of the main? Is that a 3/4" pipe or is it a 1/2" pipe? The fact you were heating the vent tells me the pipe screws into the vent so it is probably a 1/2" pipe. If the main vent threads directly into the inside thread of the main it is probably 1/2"; if the there is a pipe union between the pipe and the vent (main vent exterior threads goes into the pipe union) then it is probably a 3/4" pipe. just measure the length and pick something up at a supply store or even HD, get a pipe union if you need one also. BTW that vent really should be about 15" back from the end of the main; with a close nipple and a couple of elbows you can go back along the top to position it. Try to make sure the vent ends up at least as far as the old one - maybe 6-8" above the main as space allows.



Now to the question of what kind of main vent you should use. If that old vent is actually a Marsh #55 it is probably left over from the coal era, it's rated at 0.02cfm and that is really too slow for today's boilers. How long and what diameter is that main? You want to vent all the air in the header and main quickly so we have to figure the pipe's volume to select the correct vents. Your choices are usually Hoffmans (4a is 0.216cfm and 75 is 0.75cfm)  or Gortons (#1 is 0.54cfm and #2 is 1.75cfm). If the mains are different lengths and/or diameters you may need different vents on each main. Vents are not cheap but they tend to last a long time. You can construct an antler if you need to more than one vent to get the rate you need, just make it is sloped so the water can find it's way back to the boiler.



That T the vent is on should get steam hot, that tells you the steam is getting there, the question is how fast is it getting there.

moneypitfeeder

dimensions

Hello, I'll start with the main o.d. is 2-1/2" and that main is 38' long. At the very end of it, there is a threaded tee, on the top of the tee there is a fitting threaded in that reduces to a 1" od black pipe, then a threaded coupling to a marsh No. 5. Bottom of the tee is a 1-3/8" od black pipe, that pipe runs back along the floor to the boiler and ties in where the water inlet piping to the boiler is. (I looked at the radiator return lines, and they don't tie into that return like I originally thought.) Btw, Sorry I didn't say it yesterday, but Happy Thanksgiving! (I kinda ignored it this year we demo'd the kitchen last week!)

Thanks Dee

BobC

Vent selection

That main is 2" ID and 38 feet of it has about 1.4 cu ft of volume. I would think a Gorton #2 would be the most economical choice to vent that pipe. The Gorton has both 1/2" and 3/4" threads. You stated that the main ends with a T and the vent is on a pipe nipple that feeds the vent at one end and that the return drops from the other end of that T. For longevity that main vent should be mounted about 15" back from the drop to the return.



You can accomplish that by using a close nipple, a couple of elbows and a length of pipe to place the vent 15' away from the returns drop. make sure you configure this so any water can find it's way back to the return (slope it towards the return pipe) and keep the vent as high up as practicable.



Bob

Rod

March # 5

Hi- Just thought I add a couple of things. I believe there is a March # 5. It's a vacuum vent and its venting capacity is somewhere between an Gorton #1 and a Hoffman 75. Steamhead mentioned them a couple of years back.

I've attached a drawing by Brad White, of an venting "Antler" which helps get the vent away from the end of the pipe. Note the use of the pipe union . This allows you to easily install the vent and take it down for the occasional servicing.

- Rod