Steam Main Air Valve

Alex21htr

I'm new to this forum. I'm not very knowledgeable about my steam heat system. I'm wondering if anyone can help me figure out why a two year old steam main air valve (specifically a 75, 1/2" x 3/4" straight steam main air valve) on what I'm pretty sure is a dry return pipe is leaking about 1 gallon of water every 4 days or so. Here are a couple of pictures. Is it typical to have to replace a valve like this every two years, or is there some kind of adjustment that I can make to the heating system as a whole that would prolong the life of the valve? Any insights would be appreciated.

JUGHNE

What pressure does the gauge show when running?
Post pictures of boiler piping, floor to ceiling.

Jamie Hall

That main vent should never see water. For that matter, if it's really a dry return, it should never see steam either. As @JUGHNE says -- pictures, please, and pressure?

ethicalpaul

Is it leaking liquid water or gaseous water (steam)?

Alex21htr

This is where things get even more puzzling. The pressure gauge never displays anything but zero. Here are some more pictures.

Alex21htr

I'll try and take/post a ceiling photo this afternoon. Thanks for the input so far.

Alex21htr

Here's are a couple more images.

Jamie Hall

Several comments. First, I still can't tell whether that pipe to which the vent is attached is a dry return or a steam main extension. There is a critical difference.

Second, the pressure gauge may never show pressure. That's the standard 0 to 30 psi gauge required by the insurance and code people. They aren't accurate -- if they work at all -- at the low pressures seen in residential steam. So not to worry about that.

Third, if that pipe with the vent on it really is a dry return, it will get flooded any time the boiler pressure goes above about 1.4 psi. The vent may -- or may not -- be able to close with the water in there, or it may have failed so that it won't close with water (it should, when new).

Fourth, I can't make out what the pressuretrol is set to.

Alex21htr

Thanks a lot for the comments.

#1. That pipe to which the vent is attached ends up at the same valve that I use to flush the system every couple of months. Not sure if this helps but the section of the pipe where the valve is located is about 38" above the suggested normal water level of the boiler. It's hard to tell from the photo but about 20" after the valve the pipe drops down on a 47" long vertical and then makes its way across the basement along a sloped pipe, until it reaches the flush valve that I mentioned. This is what makes me guess that the length of pipe where the valve is located is a dry return. Not sure if the diagram that I included helps at all. As I mentioned earlier I'm not very knowledgeable about the system, or the terminology, but I hope I'm understanding the basic ideas of dry and wet returns so as not to confuse.

#2. Thanks for clarifying the question about the pressure gauge.

#3. Do you know if there's something I can to do to prevent the boiler from going above 1.4psi so as to prevent this flooding? Once the flooding problem was addressed would it be a good idea to get a new valve on there?

#4. The pressuretrol is set to 2psi. Should I set it lower to prevent the flooding that you mentioned?

Jamie Hall

On whether that pipe is a dry return or a steam main extension -- which is a critical question -- it's what at the other end of it -- the far end -- that counts. Does it connect directly to a steam main, or is it separated from the steam main by a steam trap -- and if it is, is the trap working? If it's the latter, it's a dry return, and when the boiler reaches over 1.4 psi or so it will flood. If it's connected directly to the steam main, it's a steam main extension and will see boiler pressure -- and won't flood.

JUGHNE

It looks like you have 2 mains and 2 returns, yet you show only 1 vent on 1 return.
Any other steam main air vents?

Alex21htr

Jughne, yes there's a second vent on another dry return that's not included in the drawing. Using the naming convention that I started with, I'd call it "Dry Return (West)." Here's a photo of this second vent.

I should mention that this is 4 unit rental, so it's a fairly big system.

Alex21htr

Jamie,

Here's a photo that I hope might provide some clues at to whether the pipe with the 1st valve that I mentioned is a dry return or a steam main extension.

At the far end (near the South window) it looks like the "Steam Main (West)" pipe runs parallel to the far wall for about 4 feet, and then comes back away from the window as what I've been calling the "Dry Return (East)" pipe. It looks like there's another 4"(?) pipe that ties into the middle of this 4 foot long run that's parallel to the wall.

Thanks again,
Alex

JUGHNE

Can you show how the steam main and the return are connected together?
Is there any sort of trap on the end of the main?

Alex21htr

I'll take a closer look, and get back to you on that.

Alex21htr

Here are some more photos of the end of the steam main. I don't see anything that looks like a steam trap, but there is a valve in the middle of the 4 foot run (the run that's parallel to the far wall). Since there's nothing that looks to me like a steam trap, and based on the information you've offered it looks like what I've been calling “the Dry Return (East)” might actually be steam main extension. Hope this helps.

Jamie Hall

Nice pictures! In act, uncommonly well done.

I have no idea what that valve is for. Can you tell if it is open or closed? And where does the pipe which it is on go?

As that is piped, it really is a steam main extension -- but a lot of folks refer to it as a dry return anyway, so as long as we know what we are talking about... !

Let me think on this some more...

EBEBRATT-Ed

On the boiler I doubt that header is 24" above the water line=wet steam

neilc

EBEBRATT-Ed said:

On the boiler I doubt that header is 24" above the water line=wet steam

ok, so, low header height,
and what looks like dirty water in the sight glass,
how much does that bounce when steaming?

questionable pressure due to non registering pressure gage,
I'll ask about the pigtail,
(steel, more prone to fouling),
has it been checked and cleaned, all the way back to the boiler?
consider adding a low pressure gage when you check the pigtail.

that leaking vent looks dirty/old,
you could try boiling it in vinegar to clean it out,
or replace it?
also looks lower elevation compared to the other(?)

Alex21htr

Thanks for the comments. I'll re-measure the header height today, and post it here.
The range of the water level bounce (from lowest level to highest level) when the burners are on is somewhere between 1/2" total fluctuation and 3/4' total fluctuation.
I haven't checked or cleaned the pigtail. I don't know what to check or how to clean it. I'll do some homework on this.

BobC

I had two Hoffman 75's fail to close within two years so i don't trust them. For a little more cost you can go with a Gorton #2 and get a lot morte capacity as well.

Jamie Hall

BobC said:

I had two Hoffman 75's fail to close within two years so i don't trust them. For a little more cost you can go with a Gorton #2 and get a lot morte capacity as well.

Don't shoot the messenger on this one, Yes, Homan's sometimes fail (though I have one which has been going to 90 years now). However -- the problem isn't that, real though it may be, the problem is that sometimes solid water gets up there and splurks. That shouldn't be happinging.

Alex21htr

I re-measured the header height, and realize that I had left out an important section of pipe in the drawing that I had posted. Hopefully, the following two photos will help to clarify things.

JUGHNE

Jamie, what if he drops that wet return down to the floor?
That would give him more height of water column that the steam might not push the condensate up into the dry pipe.....yes, extended steam main.

And what would some bad rad traps do to this situation?

Also BTW, if the end of main simply turns back towards the boiler by way of the return, what keeps steam from traveling up the rad trap drops to close those traps.

His drawing shows this to be a 2 pipe with rad traps.
What keeps the steam main steam out of the return piping?

neilc

I don't think you get to refer to that higher horizontal as a second header. #smiling.
Do you have your boiler manual? to see the piping diagram?

Your header is the horizontal right above the boiler, (too low)
Where the header turns back down to the floor and the boiler return, the header becomes your equalizer,
The header down turn, "equalizer", is where any wet steam condensate that separates out in the header drops back to the return,
Taller risers out of the boiler also contribute to dryer steam,
In your case, wet steam may be getting up into the system mains, (that higher horizontal), and getting carried out thru the system.

I still think checking the pigtail, the looped pipe under the Ptrol, is warranted, to rule out pressure issues pushing water up the return to that lower vent,
When the boiler has been firing for a bit, does the water level drop much in the sightglass, how much?
guessing it does as water is leaving that vent.

there is one more possibility,
Is that wet return free flowing, and not clogging / slow flowing?
do your wet returns have drain valves or caps that you could try flushing / draining possible cruds?

Alex21htr

Thanks neilc. Yes, this is where my lack of knowledge shows through
Below, I'm posting the only two pages in my manual that reference the piping.

If the header is too low can I call the company that installed it, and have them correct the height, or is it more complicated, or am I oversimplifying things here?

If I'm not mistaken there is a drain valve for the wet returns. I flushed the wet returns about two months ago, and the water looked pretty clean. Is every two months a good span of time for draining these pipes?

jughne, as far as the radiator traps some of them are quite old (at least 16 years). I could start replacing them if that helps. I replaced them in one of the apartments about 4 years ago.

neilc

woop here it is , , ,

and you don't have 24.
what you have there is a basically correct design, that is a bit low,
it might work well enough as it is.

Is this a new install with responsive contractor?
or are you asking if it's worth pursuing having the header raised?

I would try these other things first before repiping the boiler.
pigtail and pressure question,
clean(boil) or replace the leaking vent,
the water in the sightglass looks murkey, skimming and a flush may be helpful,

flushing the wet returns is not a monthly chore unless you're dealing with extreme crud conditions,
and by then your wet returns are likely leaking also, necessitating replacement,
you shouldn't have to flush more than once every several years,
just for giggles, post a picture of the wet drain you got the clean enough water from.

Alex21htr

Thanks a lot for these detailed recommendations.

chuckadoo

Looks like newer vertical piping at the end of return. Still have good pitch?

Alex21htr

Below is a picture of what I think is the "wet drain". This is where I've been draining the system every few months or so. I then add water manually using a valve that's next to the automatic water feeder.

Another problem that I've noticed, and maybe another clue as to what the problem might be, is that the overall water level always keeps rising.

For example nine days ago (March 22) the water in the glass gauge was at the normal level, where it should be. This morning, one of the tenants mentioned that the radiators in her apartment were making a banging noise. I looked at the glass gauge, and it was completely full with water. After draining 12 gallons of water from the boiler I got it back down to the normal level on the gauge.

The part that I don't understand is why the counter on the automatic water feeder is displaying the same number as it was displaying on March 22. If the automatic water feeder hasn't fed any water to the boiler since March 22 then why has the overall water level gotten so high nine days later? Where is the extra water coming from?

JUGHNE

Do you have a by pass valve that feeds water around the feeder/counter?
That valve may not be sealing 100% and water squeaks thru it into the boiler.

Pictures of that?

Jamie Hall

"I add water with the valve that's nest to the feeder". Um... unless you have a domestic hot water loop in that boiler, either that valve or the valve in the automatic feeder is leaking. They can, and do. The automatic feeder should have two isolation valves, one on each side, which are bypassed by that manual valve (if it doesn't, shame on whoever installed it). So -- to take the automatic feeder out of the equation, close both those valves and see if the water level holds. If it does, there's your problem. If it doesn't, it's the other one.

If it's the feeder you may not need a replacement; some of them the valve and strainers can be repaired separately. And don't be fooled by that counter -- it tells you how often the valve has been actuated, but doesn't actually read the amount of water toing through.

JUGHNE

Maybe I missed something or have my head screwed on wrong....I'll ask my first question again:
What keeps the steam of the main from backing up the rad trap risers?

Jamie Hall

The only thing keeping steam out of the return risers on a two pipe system with dry returns -- or for that matter wet returns -- is the traps on the radiators (or orifices or widgets... something). If you have a steam main which needs to have the air get out and the condensate get out to an adjacent dry return, the air can get out OK with a crossover trap or a vent -- but the condensate has to be released through either a loop seal or a drip into a wet return, and in either of those it will rise that old familiar 28 inches above the boiler water line for every psi in the boiler.

Is that what you were asking?

Steamhead

That too-low header is almost certainly causing wet steam, which is hard on vents. Have it repiped, then see if the problem goes away.