New main vents, but mains seem unbalanced

[Deleted User]

After learning a lot on this forum, I fought my way to my two main vents. They were plugged, and I replaced them with Gorton #2's. I made sure both would pass air freely when upright at room temperature.



On one, I can detect the air flow by holding three of the little holes closed and listening for air on the fourth. And it gets pretty hot and I can tell it's closing.



I haven't been able to detect air coming out of the other one, and it never gets more than warm. Strangely, some of the radiators on that main heat well (including the last one), but others very poorly (long distance from main).



Even if something's wrong with the radiator vents, it seems I should still get steam to the main vent. The boiler is probably 90 years old. Are there two boiler chambers with separate pressures? Otherwise why wouldn't they both act the same?

BobC

Venting

How long is each main and are they sloped properly along the whole length? What pressure is the boiler operating at when producing steam? I assume this is single pipe steam, what kind of radiator vents are you using?



Post some pictures showing the boiler and the piping around it (stand back so we get a sense of how the system is configured), also post pictures of the mains and vents.



Bob

[Deleted User]

Info and pics

Thank you. The mains are each about 60-62 feet. They seem to be sloped slightly all the way. Never have any water hammer or gurgling. These pipes are definitely the original; I don't think any live man has touched them. The boiler doesn't look like it's had any major work since conversion from coal to gas eons ago. Only exception is addition or replacement of the automatic water feed and low-water cutoff and a valve that I flush once a week.



Single pipe from the main to radiator. Most radiators have Hoffman #40 vents. Based on advice here I was trying to get the main vents functioning well before trying to balance the radiators.



The pressure I don't know. The pressuretrol is set at 4 and 2. The pressure gauge never budges from 0, but it is ancient and I don't know if it works. (I saw someone here was installing a 0-5 pressure gauge. I haven't been able to find them online.)



By the way, I ordered a bunch of pipe insulation and insulated the mains as best I could, but the fittings are bare and some sections of the mains too.



Here's a photo journey into my dungeon. Sorry that the website and my iPhone don't seem to agree on verticality.

BobC

More

If your mains are both about 60 ft long and if I assume they are 2-1/2" pipe, each main has about 2 cubic ft of air in it so you probably need at least 2ea Gorton #2 on each main.Can you tell how far the steam gets on the slow main?



Steam will follow the path of least resistance so it seems you have less resistance on the fast main that you do on the slow main. make sure all the radiator vents on the slow main are all working and stretch a string along the slow main to check for any dips. A dip will collect water and cause the steam to collapse, it might or might not bang when doing so. Make sure the radiators are pitched toward the steam supply pipe.



How long does it take the steam to get to the end of the fast main normally? Is there a lot of hissing from the radiator vents when making steam? Lowering the pressure would probably be a good thing to do, try adjusting it down to 2 and 1 or 0.5 and see if that makes a difference. You can buy a low pressure gauge from -



http://www.grainger.com/product/Press-Gauge-18C773?functionCode=P2IDP2PCP



or



http://www.valworx.com/product/low-pressure-gauge-25-0-3-psi



You should not need any more than 1.5PSI to run a steam system and lower is better. If you add one of these make sure you do it on the end of a pigtail, you could just T off the pressuretrol fitting to add another gauge. While doing this make sure the pigtail is clear, they tend to gunk up over time and then the gauges and pressuretrol can no longer see whats going on inside the boiler.



Bob

[Deleted User]

Things to ponder

Actually, the mains are 3" and reduce to 2.5" about halfway. But still, those Gorton #2's seem adequate. Before I installed I blew hard through them and it was like nothing, blowing through a short piece of 1/4" pipe. The vent certainly seems to work fine on the hot main, and as I say doesn't seem to restrict the flow of air until I cover three of the four holes on top.



I suspect my pressure might actually be lower than 2-4 lbs. There is no hissing anywhere. The radiator vents just release a soft flow of air that you can hardly notice unless you stop it. But thank you very much for those links, I will definitely get a low-pressure gauge and adjust the pressuretrol if needed.



That's a good tip about a dip in the main. I will survey for that. Also when you mentioned that, I realized the last ~8 feet of the bad main is not insulated, so maybe the steam is collapsing there before it reaches the vent? I'll try to feel all along the main to see where it stops being hot.



I don't see how radiator problems would cause this, unless a vent fell off the radiator and is just open (which isn't the case). Anyway I'll check them and their pitch. If an old radiator is on a level surface, is it designed to drain slightly toward the valve? I'm guessing not since it could be used in a two-pipe system?



Anyway thanks for the ideas Bob, gives me some things to try.

Jim

conversiontime

remove main vents, fire briefly

To test if steam exit the vent mounts around same time. Be careful not to get burned and shut off boiler once you note steam arrival timing.



That looks like a real workhorse, have you ever had it tested for efficiency? Always impressed how long some old boilers last but assume their efficiency is lower so just curious.

Paul48

Curious

Did they reduce the mains using eccentric couplings?( so as not to hinder condensate)

[Deleted User]

Dumb questions

Efficiency? no, it's probably best that we don't know that!  I've read somewhere boiler like this might be 50% efficient or less.

So when you take the main vents off, are you actually detecting steam visually, or what?

What's the best way to fire/turn off a boiler like this for that kind of testing?  Well, I've noticed that it won't work without electricity, so should I just turn that circuit on and off for testing like this?

Finally, a follow up to Bob's links to low-pressure gauges.  I notice those gauges don't mention steam, and the operating temperature only goes up to 140 F for one and 160 F for the other.   Are they still OK for a boiler?  Maybe as long as they don't leak, no steam actually get's to them, since there's nowhere for the air to go?

Paul48

Hence

The pigtail, always full of water

[Deleted User]

You guys are knowledgeable!

And that answers two questions I had with one blow, the other one being, "why the pigtail?" !

[Deleted User]

No

These look like concentric reducers, but they are on both lines, the fast and the less-hot one.

conversiontime

piece of tissue or cut paperboard cap, etc

Place over vent mount hole, the air will flutter it first then steam should arrive shortly thereafter. But basically see if both start reacting around same time.



Re gauges, you can find 0-3 WIKA gauges which is what I use. After only one year the needle is off a bit though so not sure of quality. I believe the needle can be adjusted but have not bothered since it answered my questions after one day (that the boiler pressure is very, very low on normal firing).

Mark N

Main Vents

Have if you swapped the vents around? That way you can determine if it is a vent issue or a main issue.

[Deleted User]

Great idea!

I can do that in conjunction with removing the vents to measure the arrival of steam to the vent locations.



Another thing occurred to me based on another thread.  Could there be sludge built up in the pipe somewhere?  After I do the steam timing and vent switching I can start narrowing down the possibilities.

ttekushan_3

You could try an easy experiment.

If you never see any pressure nor hear any hissing, you could be a bit over vented. (I know, that's a scandalous thing to say around here:-) )



You could put a wrap of tape around the holes on the fast main's vent and punch a small hole thru the tape and see if the mains heating time changes. I'd leave the big Gorton #2 on the slow main alone. Increase the size of the hole in the tape on (originally) fast main until they equalize. You might find you only need a Gorton 1 in this position.



The other thing I can't see from here is what the cumulative radiator venting capacity exists on the radiators of each branch. That will affect it too. As little total restriction as is practical for good distribution is what you're looking for and restricting the fast main just a touch might be the easiest thing to do and get the desired end result.

[Deleted User]

Results of 2 experiments

ttekushan, that sounds like a good experiment, but I started with the two experiments suggested earlier:

1. removing the vents to see which main gets steam to that point first, and

2. reversing the vents to see if that affects behavior of the mains.



And the answer to the question, is it the vents or is it something with the mains is -- maybe both!



Let me first say, with my limited experience, I am not at all impressed with these Gorton vents. One of the two I ordered was DOA, did not vent at all. Now it appears that the other and the replacement have noticeably different venting capacity.



First I removed the vents and fired to monitor time to steam for the two mains, as suggested by conversiontime. The arrival of steam was not a distinct event as I expected. I gradually felt a warming and moistening of the air from the two pipes. At 2:14, the fast main got pretty hot, but I could still hold my hand on the opening for several seconds. The slow one was warming but not as much. There was never big fluttering of the tissues over the holes, very minor. But by 5 minutes, I did burn myself slightly checking the fast main (turns out steam is invisible - who knew!). The slow one was not that hot, but it was gurgling quite a bit. Afraid of hot spray, I shut it down.



Conclusion: the mains are different, the fast one is inherently faster for some reason



Now to reverse the vents, as suggested by Mark N. First, I blew into the cool, upright vents. The vent that came off the slow main seemed noticeably restricted in air flow compared to the one from the fast main. I put them on in reverse and fired. Now I could feel air from the "slow" main, but not from the fast one. And the formerly slow one got hot faster.



Conclusion: the vents are different, apparently enough to cancel and even somewhat reverse the difference in the mains



I will be calling Gorton tomorrow, but still have a difference in the mains I need to find the cause for. But actually, here's another hypothesis. The main that HAD had the slow vent on it was colder. So when I removed the vents, it took longer for the steam to make it to the end. The main that had the fast vent removed was hot, so the steam went faster. Maybe it's all due to the vents???



Edit: in fact the gurgling from the "slow" main suggests that there was a lot of condensation, supporting the idea that this one was slower because it was colder, only because it had the slow vent on it just before. Does that sound right?

BobC

Aside from the bad vent

It seems you have water sitting someplace that maybe condensing the steam from what you said -



Edit: in fact the gurgling from the "slow" main suggests that there was a

lot of condensation, supporting the idea that this one was slower

because it was colder, only because it had the slow vent on it just

before



I couldn't tell from your pictures, do the two boiler risers feed different mains? It looks like you don't have a boiler header or equalizer but that might just be the angle of the pictures. If what i said is true then the boiler piping itself could be responsible for what your experiencing.



Bob

[Deleted User]

Risers and mains

No, it's simply two pipes coming out of the top of the boiler and going their separate ways, never to meet again until they both go into the bottom rear of the boiler. As far as I can tell it's the way it was built 90 years ago. Should there be more? Are they supposed to be connected near where they come out of the boiler?



As far as the water sitting, I was thinking (hoping) a lot of condensation occurred because the steam moved fast because there was no vent in a relatively cold pipe. Is that a pipe dream? ;-)

BobC

What changed?

I glossed over the fact you had the vent off (my bad) but the key would be if main one is acting differently than main 2. If you were to replace the boiler the near boiler piping would be completely different. Old boilers have huge steam chests compared to anything made today; the key would be has the system ever worked right to your knowledge?



The fact the two mains act differently is an important clue. A building that old has settled and the settling might have changed things.



Bob

[Deleted User]

Do the mains really act differently?

Well my hypothesis/hope is that the difference in the mains is entirely due to the vents. Even without the vents, the difference may have been due to the one with the slow vent being cold.



I've only been in this house 4.5 years. I hate to say it wasn't well cared for in recent history, but I certainly can't say if the steam system eveer worked well. I'm starting to think, though, there is a chance that equal venting of the mains could result in equal behavior. If not, perhaps balancing with a judicious application of tape on the vent or something. Already by reversing the vents, I'm getting more heat into two cold upstairs rooms than I had.



Replacing the boiler is definitely going to happen when we can afford it. But other than costing as much as $400 per month for gas in the winter, this one is working reasonably well.

BobC

Do what you can

Insulate any piping you can reach and get the pressure down to 1.5 PSI or less; that should save a little off the bill.



I just finished adding a fresh air intake to my boiler and I've noticed less drafts when the boiler is firing. Insulate anything you can (attic sill plate, etc. Other than that hunt down and kill any and all drafts!



Bob

ttekushan_3

come to think of it, the gortons

I guess that's why I have still an affinity for the old Hoffman 75, they're pretty consistent and, despite their slower venting capacity, they have a positive "clink" sound as the snap bellows pops the vent closed. It also acts as a float should the system flood. Very soon after cool down they positively pop back open. There's no "sort of open" when everything's merely warm. Due to their slower vent rate compared to the gortons, I've had to put two on a "tree" to get the faster venting.

So I'll go out on a limb and recommend the hoffman 75 main vent instead. Having said that, I still prefer the Gorton radiator vents due to their use in proportioning steam systems based on radiator size, and that feature of being somewhat closed (or not fully open) on a very hot radiator actually serves to help equalize the heat that each radiator puts out from cycle to cycle. This feature only seems to backfire on steam mains. On radiator they're the best