Venting - main vents

paulM_2

hi there!
I have a two story residential house built in 1932:
1-pipe steam system, w/a return pipe runing parallel from main vent back to the boiler - wet return? 1 pipe goes into each radiator. There are two outlet pipes, one feeds frnt radiators the other feeds the radiators in back 1/2 of house.
PROBLEM that i was working on:
frnt radiators are working great, nice warm glow.
back radiators are nOt working - so i removed and cleaned the main vents, chcked all radiator vents and valves, found the pitch on return line was toward main vent - re-pitched pipe toward the boiler, added cleaning solvent and now everything works.
QUESTION is:
when i removed the main vent and put my lips against the opening and blew a breath of air into the main steam line, a puff of air came back out = WHY??
i didn't expect it to behave like a ballon.

michael_15

Some comments from a novice

The parallel return pipe is a dry return if it's above the waterline, and a wet return otherwise. If it's after the main vent (which should be right at or after the last radiator takeoff), then it's not a steam-carrying pipe and hence a return.

So do you have two supply mains with a main vent on each? Perhaps a picture of the system would help.

I believe the supply main should actually be pitched away from the boiler and towards the main vent, if I am understanding your description correctly. This makes it a parallel-flow system; condensate will run towards the main vent as well, but that's okay, because it will flow by gravity into the dry/wet return and go back to the boiler that way. This is a good thing, because you don't have condensate and steam moving in competing directions.

I'm not sure I understand your blowing air into the steam line question. So you just blew into a hole in the pipes? I hope you put some plastic or something between your lips and the pipe. . . Anyway, if you blow into the main steam line, it'll attempt to shuffle air out of the other vents in the system. To the extent you blow hard/fast enough so that the other vents can't vent it, you'll just increase the air pressure within the system, so when you take your lips off, a puff of air should come back out. It has to go somewhere, after all.

-Michael

chuck_6

Paul,

You may want to measure the diameter of your mains, and also the length of each main. It sounds like the back part of the house has a longer main, in which case you want to vent that main quicker than the front part. If you have upstairs rooms that are far away from the boiler you need Gorton D vents on those radiators

Measure the diameters of the mains and length of each main and re-submit. I'm sure Steamhead will respond and he can tell you what vents to use.

Chuck

Steamhead

\"Balloon\" effect

What you did by blowing into the main was slightly compress the air in the system. It re-expanded and blew out the main vent hole when you removed your mouth. This is normal.

Measure the length and diameter of your steam mains and we can tell you what vents you need. If the pipes have old insulation on them, measure its outside diameter without disturbing it. Subtract 2-1/4 inches from this and that should be your pipe size.

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paulM_2

update - pipe sizes & radiator sizes

here is some more info - radiator are painted and exposed with no covers - BOILER hb smith, G210-S-6-CON, sn: H80-1348, in: 187.5 BTUhr, out: 150 BTUhr - only one riser into the header - two main steam supply lines (no insulation by the near boiler piping is copper, but steam lines are exposed and steel and it's easy to measure) about 7.5 Circumference is about 3" dia steel pipe ;;;; FRONT - insulated length frm header Tconnecter to main vent is 290", main vent Dole No.1933. Feeds the following five radiators: ( 1st flr ) mckeesport 3 tubes 5 fins, 11.5"L x 5"w x 36"h maid O mist Jacobus vent; aero 5 tubes 5 fins, 11.5"L x 8" w x 29.5" h, maid O mist vent; arco american radiator 6 tubes 24 fins, 41.5"L x 8"w x 25" h, maid O mist Jacobos vent; ( 2nd flr ) aero 5 tubes 11 fins, 26.5"L x 8.25"w x 23" h, maid O mist Jacobus vent; aero 5 tubse 12 fins 29"L x 8.5"w x 22.75"h usav884 vent ;;;;; REAR - insulated length frm header Tconnector to main vent is 414", main vent usav880B. feeds the following five radiators: ( 1st flr ) aero 5 tubes 15 fins 36.5"L x 8.25" w x 22.75"h usav884 vent; aero 5 tubes 10 fins 24"L x 8.25"w x 22.75"h usav884 vent; american radiator 3 tubes 7 fins 16.5"L x 4.75"w x 19.5"h usav884; ( 2nd flr ) mckeesport 3 tubes 7 fins 16.25"L x 5"w x 29.75"h main O mist Jacobus; aero 5 tubes 12 fins 29"L x 8.5w x 22.75"h maid O mist Jacobus vent. ???? WHAT KIND OF MAIN VENT & RADIATOR VENTS SHOULD I HAVE ????

Steamhead

Start here

On the shorter main (24 feet) install a Gorton #1. On the longer one (34.5 feet) install two Gorton #1 vents on a tee. Maid-o-Mist also has a #1 but the floats in M-o-M vents are plastic, so I prefer the Gortons.

Insulate the mains with fiberglass pipe insulation 1" thick. You can't get this type of insulation in the proper size at Home Depot- go to a supply house or thru your contractor.

The Maid-o-Mist/Jacobus vents have interchangeable orifices on top. These have numbers or letters stamped in them, which will tell us their venting capacities. Post these and we'll see if they're sized right.

www.gorton-valves.com

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paulM_2

details on vent number

steamhead - first thanks for taking the time to work with me!!.. gorton valves is located a few towns north frm me, i'll give Ken a call (thanks chuck for helping a fellow HU)
I have attached a microsoft word document with detailed drawings of radiator locations and boiler position.....
NOW for the valve sizes: 1st flr #5 by front door, #4 in living room above boiler; rest of them and the room w/thermostat is an adjustable one usav884.... 2nd flr #6 (or 9) in two of them and one usav884 adj vents.... GOING to start by replacing the main vents with the gorton #1 (one for shorter main and tee with two for the longer one).... NEXT going to work with Ken to size out the other valves... comments??

paulM_3

oddball main vents

took a carfull look at the main vents - they are not regular vents... there is a 1/2" threaded nipple (about 1" long sticking out of the end fo the mains) with several attachemnts off it and an 1/8" radiator vent... ?? IS this normal ??... the gorton #1 with the 3/4 or 1/2" internal threads don't fit exactly.... so i guess i'll have to try and jury rig some short stubs together and see what happens...

Steamhead

I see that all the time

you can increase the height of the 1/2" nipple by removing the reducers, installing a coupling and another nipple, and screwing the vent onto the top of the second nipple.

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Steamhead

You can probably get by

with rearranging some of your vents. The USAV adjustable is about the same as the M-o-M #5 or a little less at its maximum opening.

With the new main vents installed (not before, this will affect the distribution of steam), start by venting the two biggest radiators (6-tube and 2-column in attic) with #6 vents. Use the #5 and the USAV vents in the smaller radiators. The #4 might work on the McKeesport 3-tube 5-section radiator, if not replace it with a #5 from Gorton. See how the system heats up and make any needed changes from there.

There's nothing wrong with using your Home Depot vents until they fail, but when they do replace them with Gortons.

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paulM_3

replaced vents - still no heat but

Let's Pause - why did i start this adventure?? ORIGINAL problems - severe water hammer on frnt main radiators and no heat in kitchen radiator (kit rad has never worked in five years) and the radiators in both bathrooms and dinning room failed a few days ago (no heat), only radiator working was the first one from the boiler on the rear main steam supply in the 2nd flr bedroom;... what is COMMON to them?.. they are all feed off the rear main steam supply line;... SYMPTOMS - main vent on rear line was spitting water;.. all vents on rear line hissssed non-stop when boiler was running;... what was REPLACED - for the water hammer, raised radiators out of the floor boards and pitched them toward the supply valve, adj cutout press frm 4 to 1 psi - worked no water hammer on frnt mains..... for the no heat replaced all vents 1st flr with gorton #5;.. 2nd flr #6 back bedrm has a #C;.. attic is turned off, we do't go up there;... frnt steam supply 24' main vent Dole no 1933 (rusted on solid - not going to touch it);... rear main 34.5' main vent was usav884 adjust wide open, spitting water, removed and replaced with two gorton D setup on a 1/8" tee conector;.... STILL no heat from rear main - i can hear the steam surging through the line, rear radiator vents hisss but any radiator beyond the first one the steam encounters as it leaves the boiler never heat up just hiss as the boiler runs..... we have heat coming frm frnt rads, so i'm not ready to call 911 yet.... any IDEAS?... should i try and clean the boiler?? i have sos dry steam boiler cleaner and was going to pour some in through the relief valve... afterall it's sos :-)

Steamhead

Plugged Wet Return (below boiler's waterline)

is the most likely cause, water is backing up into the rear main causing vent to spit and possibly flooding the radiator runouts. If the water level in the boiler drops considerably while it's running, then takes a while to recover when it shuts down, that's another symptom.

Cure is to replace the wet return.

But your first post said everything was working now.....

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paulM_3

worked once - but then died

i was too haste in declaring success... it worked through one heating cycle and then died... the way i got it to work once was to pour a boiler cleaner i purchased frm home depot into the rear dry return line (dry because it's above the waterline - yes?) and then pitching the return back toward the boiler.... what you say makes sense.. the boiler short cycles and most of the water leaves the system and the water level does drop.. it eventually does return to the original level.... i'm going to remove the main vent on the rear line and pour some more cleaner into the line and see if it that works... why the vent? because i hesitate in breaking the seal at a joint on the return line - just cause it's soo old and it's hard to get the worms back in the can once they get out :-)

paulM_2

update - put hands in pocket

so far i have tried several different cleaners and pitched the dry return (one pipe system) for the rear main steam supply back toward the boiler...... still no luck.... same PROBLEM at the start of the cycle the water / steam (not sure which it is) begins to make it's way from the boiler into the dry return line faster then through the main steam line and the main vents spit and the radiators attached to rear steam line begin to gurgle...... HOW do I know?... touch test (ouch!)... when you touch the dry return that runs parallel to the main steam line it appears to start heating up first closer to the boiler, faster rate (ouch!) than the main rear steam line, which appears to heat faster further from the boiler.... time to "put my hands in my pocket"....

Steamhead

Somehow

the dry return was not dropped below the water line at the boiler, and steam is getting into it and heading straight for the main vent.

The solution is to repipe the end of the dry return so it drops below the waterline. This way the water standing in the drop pipe will keep steam out of the return.

Post some pics of the piping around the boiler, we may be able to spot the trouble.



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paulM_2

correct - the piping is wrong

You are correct - the books I ordered from the web site arrived last night. I ripped them open looking for wisdom and inspiration from the "deadmen".

I measured the dry return line last night (where it meets with the boiler - hartford loop i think it's called) and it is about 1 1/2" above the waterline mark.

The near boiler piping is copper and I was thinking about un-soldering and re-piping it using steel (which should have been done in the first place).. BUT i prefer not to practice on my own in heat in the middle of winter :-)

SO I'm going to Find a Professional and fix it together. I'll be back with an update..

paulM_2

the end of the line - fix

pressuretrol (addative) was turned down as loow as it should go (1psi) and the micro switch was tweaked.... RESULT the dry return main vent stopped spitting, but we still have some very very minor water hammer at the start of the cycle...... BOTTOM line the near boiler piping is incorrectly piped and eventually have to be replaced.... COST $1,500 estimated...... THANK YOU EVERYONE for your help... cu later!....

William Faust

Missing main air vent(s)

V-shaped fittings near the F&T traps - but what the heck are these things anyway (below photo)? Why are some of these fittings' downward-pointing legs capped whereas another one has a valve? They shouldn't be plugged but should all have valve's for clean-out purposes?

NOT A) a plug on main # 3's Right side - I've determined that this fitting originally fed a radiator.

BINGO a plug on main # 4 - This is about 10' laterally from the boiler. Our system apparently had only a single main air vent.

William Faust

Two Questions

The first question pertains to my effort to figure out where our missing main air vent(s) were located.

Our 4-story 1905 Philadelphia home's original two coal burning furnaces were converted to fuel oil in 1926. In 1946 they were replaced with a two-pipe fuel oil-steam system. A Weil McLain LGB-6 series 2 gas boiler replaced the old boiler in 1998. Input is 650,000 Btu/h, min. input is 325,000 Btu/h and AGA gross output is 526,500 Btu/h.

There were originally approx. 46 radiators of which 6 have been removed over the years. There are three mains with diameter of 2.5", 3.5" and 4.5". The small one is a counterflow main. The longest run of main-to-radiator steam supply pipe in the house (basement to 4th flr.) is approx. 80'.

The 3.5" main does a "T". At either of its two ends, and also at the end of the 4.5" main, smaller diameter pipe runs into a V-shaped fitting - a brass fireplace poker is pointing to it in the attached photo - and this in turn runs into an F&T trap. You can see that one of the V-shaped fitting's outlets (on the side closest to the F&T trap) is plugged whereas there is a valve on such outlet on another such V-shaped fitting. What the heck is this V-shaped fitting? Should I have main air vents on these fittings? If not, what is the purpose of the 2nd outlet?

If there should NOT be vents on these fittings, there is only one other logical location. This would be on the 3.5" main approx. 10' from the boiler's header where there is a fitting that is plugged. This location is a) pretty close to the begining point of all three mains and b) approx. 35' from the three mains' four ends (remember that one main terminates in two directions after a "T"). Does it make sense that our system would have only one main air vent and in that location so far from the mains' ends? What make and model of air vent should I install? I have no idea, but I would like to get a good one.

The second question is sort of general. Assume that our entire system is in fine working condition and that it has proper main air vent(s). We usually don't heat the 3rd floor's 7 rads, the 4th floor's 8 rads and an enclosed rear staircase's 4 rads in the winter. This total 19 unused rads compares to the approx. 46 that the system originall had and the approx. 40 that it now has. We do this to cut down heating costs. Would not operating these rads actually be counterproductive? I'm asking this because Holohan talks about needing to produce condensate.

Bill Faust

Steamhead

The V-shaped devices

are strainers, whose job it is to keep dirt out of the F&T traps. The extra tappings on the F&Ts are so they will fit different piping setups.

This is probably a Vapor system. The F&T traps vent the steam mains, but if more capacity is needed you can add vents there. The radiators, assuming there are two pipes connected to them and no vents on them, vent air into an overhead (called "dry") return which also collects the condensate from them. At or near the boiler, the air is vented and the condensate is returned to the boiler.

If someone has added a condensate tank and return pump to the system, the tank has a vent which discharges the air.

Take some more pics of this system and we can tell you more about it.

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