Finding Main vents

Jay_11

I purchased an old house with a one pipe steam boiler system and direct fred water heater. After a very difficult search process to find a contractor to replace the boiler and hot water heater and with lots of help from Dan H. and answers from the helpful folks on the wall, I have been able to find a local contractor who seemed knowledgeable and willing to do the job a I requested (steel piping, adding a flush valve to the return, electronic water feeder, system flushing etc.)--all that good stuff.

Here's the problem: the boiler is in a completely finished basement with only the near boiler piping exposed--everything else is sealed up in sheetrock. In order that I only do this boiler once--I asked the contractor to find and replace the main vents. He agreed to do this on a time and materials basis since we have no idea where the vents are located--we simply have to start cutting holes in the ceiling--this seems painful to me but fair enough. I have an idea where one of the main vents may be--as the wooden floor above the basement is warping in one section and I suspect this could be becuase of a malfunctioning main vent spitting out steam. But as to whether there are others and if so where they may be, I have no idea.

Before the contractor starts cutting a bunch of holes in the ceiling, I wanted to ask the Wallers whether any of you have had to deal with this problem before, and are there any tips or tricks you can pass on to allow them to find the vents with less "swiss cheesing" of my basement ceiling. (I'm hoping that the contractor is a good Battleships player).

Thanks in advance.

Mark W

Swiss, Monterey Jack, Extra Sharp Cheddar Cheese

No experience in dealing with your particular situation, but I got to wondering...

It should be easy enough to determine which radiators are at the end of the steam mains...

What if, at those radiators, you substituted an appropriately sized tee for the radiator valve, and installed a main vent there? Being that it's one pipe steam, if you still wanted a valve, you could install the tee, and bump the radiator over a few inches, install a straight valve, (as opposed to the angle radiator valve that is currently there), and reconnect to the radiator that way.

I'm not saying it'd be the prettiest thing in the world, to have a main vent sitting next to a radiator in an occupied room, (but who really notices these things anyway, as long as the heat is on; and for the people that would take notice they would probably say, "cool!") but it may be the most practical/economical over the long run. Even when the main vent is found in the basement ceiling, a big enough hole will need to be knocked out to get an arm & hand into it to get the old vent out, and most likely an even a bigger hole yet, when the old *&% vent won't come out without a 2' pipe wrench and plenty of swing room.

Plus, if it's easily accesible "above grade", when the main vent pukes again, you'll be able to replace it yourself.

Of course if you knock holes in the basement ceiling, and you eventually find the dang things (and I've seen them in spots you'd never expect, I don't think *all* of the dead-men were experts!), I'm sure you'd leave means of access for future repairs, and just patch up all the other test holes.

Sorry I can't be more helpful with the overall mission, just trying to provide an alternative thought. Whatever you do, just make sure you install good, high quality main vents!

Steamhead

If you can find

the vertical "drip" lines that connect the mains to the returns, you'll know where the end of the steam mains are and can start from there.

I think it would be worth it to open the ceiling to find the vents. If there are old vents in there they may leak, causing damage. You can install access hatches in the ceiling to facilitate replacing the vents when the time comes.

If the mains have no vents, Mark's idea of installing them at the last radiator riser would be fine. Then you could just close up the ceiling and forget about access hatches.



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Jay_11

Thanks for the idea

We cut a few holes in what he thought were some likely places and didn't see any main vents. He's starting to think we're not likely to find the main vents without taking down large parts of the ceiling--no just swiss cheese holes.

Interesting idea of putting a main vent where the radiator valve is now. I'll suggest this to the plumber. The radiators have radiator covers and so appearance won't matter. Is this job a time-consuming one? Wouldn't having the air vent on the radiator serve the same purpose? I'm asking for the contractor to replace all of those as part of the job.

I've noticed that a couple of the floorboards near the radiators on the first floor have warped a bit and I had suspected that there might be main vents underneath that might be spitting up steam, but when we dug the holes near there we did not see any main vents yet. He suspects that it might just be the heat from the steam pipes warping the wood without a main vent. If it is a defective main vent that is spitting out steam that we do not replace, will replacing the radiator valve with a main vent eliminate or minimize that problem?

We have managed to find the piping where the dry return turns into a wet return. He says that even if we can't find the existing main vents, it might be worthwhile to install a main vent there. Does that make sense?

Steamhead

answers

You need to vent the radiators and mains separately. These are two distinctly different jobs. If you try to vent the main thru the last radiator, that radiator will overheat.

Those radiator covers are probably wasting lots of fuel. See the following Hot Tech Topics for more info:

http://www.heatinghelp.com/newsletter.cfm?Id=77

and http://www.heatinghelp.com/newsletter.cfm?Id=115

The warped floorboards might have been caused by the heat coming off the pipes, but I suspect you have some steam leaking from the packing nuts on the radiator shutoffs, turning to water and wetting the wood. This is a more likely cause, and one that the radiator covers would hide from you. Tighten or repack the nuts to cure it- no need to buy new shutoffs.

If you have a bad main vent in the ceiling, you must replace or relocate it. If it keeps leaking it can not only damage the ceiling, but if the low-water cutoff on the boiler doesn't do its job it can lead to a cracked boiler.

Try to find the place where the steam mains turn into dry returns. If the system had main vents, they should be placed there. If not, that's really the best place to put them, but you'd need those access hatches..

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Jay_11

More on the system

I didn't think the warping was from a loose packing nut from the radiator because the warped boards are actually about 4 feet to the right of the supply valve. The boards right next to the radiator valve are not warping. Does thats sound right?

Thanks for the concern about the radiator covers. They are made of thin metal--are mesh on the front and we prop the covers open during the winter. I think that's about the best we can do without getting rid of them completely--which I've thought about since our fuel bills are horrendous, but the wife won't have it.

We've only cut 2 holes in the ceileing thus far. One hole shows an interesting dynamic. The boiler has 4 steam mains extending from the main supply line that extends from the header. One of the steam mains going north, about 6 feet before it splits into the line that supplies the first radiator, it forks with the main pipe going straight and filling the aforementioned radiator and the second prong does a kind of u-turn south back to the boiler and is the pipe that turns into the wet return. It is somewhere on this pipe that the contractor is positing either finding the main vent or adding a main vent. Does that sound sensible?

Mark W

More food for thought

I forget all the details on the articles about radiator covers, other than if they are not designed properly, they can severely restrict heat output. If I recall correctly, there are ways to use radiator covers without restricting the heat output. Please forgive my blatant laziness in not going back to review the articles, but I think that is part of the equation you can ably handle on your own.

As a side note, you don't mention whether it is for asthetics or safety that your wife is opposing the removal of the radiator covers, but I am typically more inclined to always recommend keeping a [properly designed, efficient] radiator enclosure for a steam heated system. A 200 degree or more hunk of cast iron is nothing to fool around with!

The high heating bills may be partially caused by poor enclosures, but I also have to wonder if your boiler has been short cycling due to the lack of or poor condition of the main vents, which would also drive up the cost of the fuel bills at a "normal" setting of the pressuretrol (cut in 1/2 psi, cut-out 1 1/2 psi) and even more if someone in the past cranked up the pressure in a misguided attempt to overcome a lack of sufficient venting.

Anyway, Steamhead makes an excellent point about finding the source of the steam leak in the ceiling and repairing it, one I agree with 100%, and I thank him for covering my back on it.

I am not always the greatest at making pictures out of words, but if you do indeed have four branches of your main, you would probably be best served by installing main vents on each of those branches. In a one pipe steam system the venting of the air from the mains, and the venting of the radiators should be treated as two separate and distinct issues, as Steamhead also pointed out.

The attachment shows kind of what I was trying to get at in my previous post. The radiator shown would be the last one at the end of the main, or in your case, the last one at the end of a branch.

Mark W

Oh yeah, I forgot

If the contractor feels he can economically install (or replace if found) the main vents in the basement ceiling, that is certainly a sensible option. (And of course you'd install access panels when you're done!)

However, given your situation with the sheet-rocked basement, it might be worth it to weigh the pros and cons of each option, both in terms of intial cost now, and in ease of servicability in the future.

Plus, if I forget to mention it before, once you do install the main vents, don't install any wimpy, cheap, undersized vents. Like anything else, you get what you pay for.

Steamhead

Yes, the vent for that main

should be somewhere before it drops to the boiler. But your description sounds like that pipe only feeds one radiator. If this is true, the vent on the radiator should be enough if properly sized.

To make your radiator covers more efficient, find some nice register grilles (maybe have your wife pick them out) and install them in the tops of the covers. Make sure you have open grilles the entire length of the radiator. This will let the heat out of the cover.

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Jay_11

Thanks for all the advice

As for the radiator covers, my wife wanted them for aesthetic reasons but we now have a little wee one crawling around so safety is a big concern. However, I prop them open with a big piece of wood almost 90 degrees and so I would have thought that was as good as a grille on top. There is already a grille for the front.

It's very possible that part of the large fuel bills is due to short cycling. My existing boiler is rated at 210,000 input, 180,000 output. After doing a radiator count (I think he came at 340 -350 rad sq ft), the contractor is installing a Burnham IN5 which I think has a 140,000 btu input. I'm hoping that should save a bit on fuel. I'm hoping he sized that right--another contractor came out about the same, but other contractors who supposedly also did a rad count came out at 200,000 btu inputs. And of course this description omits the half dozen or so contractors who didn't believe in rad counts--don't worry, I read Dan's book and showed them the door. For spaciong reasons as the boiler room is very small
we also replaced the 50 gallon hot water tank with a Rinnai Continuum, I hear that should save on gas and so far the heat and water pressure are fine. The only problem is that when the system draws a lot of water, there is a very loud noise that comes from the heater--not normal. They think that it's not drawing enough oxygen from the direct vent and need to fix that.

As for the pesky main vent issue--whatever the solution, it's not going to be economical. They said they would try to look for and replace the main vents at a cost of $140/hour plus materials. While all this work has strained the budget, I would like to replace all the main vents now--I'm going to have to hire contractors to patch and paint the basement as well as have the carpet thoroughly steam cleaned and so I'd rather do this all now. Of course, I'd also build access panels if vents were found.

The problem is that the contractor is not exactly optimistic that we will be able to find the main vents even if we do rip down walls, ceilings and cabinets--yes the prior shortsighted owners of this house not only sheetrocked everything in sight but they also built cabinets in front of some of the sheetrock that the steam pipes hide behind. (I know this is sacrilege to this group, but if I had had known all the potential issues with steam, we probably would have passed on this house).

Is it possible the system has no main vents? What we might do is trace one of the mains completely and if it has no main vents, assume the other three don't have them either. Is that a crazy plan? Although there are 4 mains in the basement (2 going north and 2 going south), there are only 3 radiators on the first floor, there are 5 radiators on the second floor and 3 radiators on the thrid floor. So its very likely that each of the mains supports only one radiator on the first floor and then vertically supports others. If we were to fllow mark's siuggestion, would we add the main vent to the supply valve on the rad on the first floor or the third floor?

Jay_11

Pics

I realize that my descriptions may be hard to understand so I attach some pics. Unfortunately, the most they will probably show is that it's very hard to work in this space since everything is finished. To take the pictures of piping, I literally had to thrust my ar blindly into the hole that was cut and hope the digital camera with flash caughts something.

Pic 1608 is the old boiler. It was piped incorrectly in at least one respect that the hot water zone was piped above the waterline.

Pic 1797 is the new boiler the contractor has put in--the job is not yet complete but it looks good from what I can tell--the only thing wrong that I can see is that I requested a VXT Hydrolevel electronic water feeder and they have installed a McDonnell Miller product. To an uninformed consumer it looks to me like a very neat job in a difficult workspace. I continue to think these contractors know what they are doing, and are basically reliable guys--which is why I'm taking their fatalism seriously about the likelihood of finding main vents.

Pic 1798 I hope shows the 4 mains that spring from the boiler. Two north and two south. Pic 1798 is a hole cut that attempts to trace one of the north headers--this splits into two lines and caves behind a corner (which is behind the sheetrock and cabinets that I mentioned.

Pic 1791 shows one of the south headers.

I note that the two headers appear to be very close to the basement ceiling. I estimate that the pipe is perhaps 4-8 inches from the top of the basement ceiling. How much room does a main vent need? Is this any indication that they might not have used main vents?

Mark W

LAOSH

I assume you're referring to "The Lost Art of Steam Heating" when you mention Dan's book.

It was from that book that I "stole" the idea for installing main vents next to the radiator. I'm not nearly bright enough to come up with these ideas on my own! My copy is old, but it is on page 118. Might differ in yours if you have a newer copy; if so just go to Chapter 8, "It's all in the venting!", and read up on "Air Venting the Gerety's "Master Venting" Approach" which shows a picture of what I tried to show in my MS Paint drawing.

In your case the main vents would be installed on the third floor so as to vent the entire main and riser(s). If a particular main is only serving one radiator, I concur with Steamhead that the radiator vent should be sufficient for venting, and a main vent on that branch would be unneccessary.

I found a link to ratings on your boiler at http://www.burnham.com/ratings/Indep.cfm

Based on the sq. ft. measured, the boiler being installed is properly sized, and your old one was way oversized. Kudos to you for kicking out the other contractors who didn't measure radiators, and quoted you on a nameplate replacement.

Whether or not there are actually main vents in the ceiling is difficult to say. Perhaps there were vents at one time, but they failed or were removed and plugged off. Maybe there were never any to begin with. It's at the point where only you and your contractor can study and discuss the issue, and decide what's the best approach with the mitigating factors you have described. And of course if there is a steam leak present in the ceiling, it should be addressed and fixed, regardless of what you ultimately decide to do about the venting.

btw, I'm sure you're feeling somewhat frustrated at this point, based on your comment: "I know this is sacrilege to this group, but if I had had known all the potential issues with steam, we probably would have passed on this house "

I don't consider it sacrilege at all, and trust me, with my house, there are some days I wish I had passed on it altogether, and just stuck with apartment living. But ultimately I do love this house, so I just consider it a part of homeownership; there's always going to be some pain in the butt thing to deal with.

But you have been doing the right things by educating yourself, and finding a knowledgable and competent contractor. Eventually everything will be resolved, and you will have a top-notch steam system. And when you come in from sledding with your little one some cold winter day and feel the heat and comfort from your steam system, you will realize there are few greater feelings in the world, and you are truly home.

As I once heard Dan say in a seminar, words that have stuck with me forever, and truer words have never been spoken: "Never Give Up."

Jay_11

Thanks for the encouragement

Actually the book we have is "We Got Steam Heat"--the picture of the guy beating the radiator looks a bit like me!

The contractor came today and given that we didn't find a main vent in the area below the warping wood, he thinks the previous owner might have had a steam leak or a bad vent and replaced the piping--he says the whitish pipe in the next to last picture is not the original piping and some of the steel piping on this main is new piping. He thinks the warping wood is old water damage and perhaps the previous owners had all the main vents taken out before they walled up the basement or maybe there weren't any to start with.

The 4 mains seem to be pitched upwards (downwards to the boiler such that he posits that perhaps it was designed so that the condensate runs back down the main to get back into the boiler (except for the one main that forks into the wet return). He said that it's possible that they worked this system without mains vents because my house is relatively small in length (though with multiple floors). Since the boiler is in the middle of the house, each of the mains probably needs to extnd no more than 15-20 feet to get to the risers to the radiators and so he posits that the system may be running without main vents and perhaps there would not be a big benefit to adding main vents.

Mark W

Well...

It is possible the old system didn't have main vents, but that was back when the system was coal fired, and the system reacted a lot differently then than it would now with the on/off operation of a gas fired boiler.

I guess this now brings up the option, based on what has gone on so far, and the opinion of your contractor that you could skip finding or installing main vents for now. Once the system is up and running, it will tell you if you need the main vents or not (which it is my opinion that you will). You will know you need main vents if you hear the radiator vents venting/hissing. If you can the hear the radiator vents, you will need to install main vents!

In a properly operating steam system you should never hear the vents venting. Contrary to what most people believe, steam heat can be, and should be, one of the quietest operating systems created.

Steamhead

You have a Counterflow system

except for that one main that has a return. And yes, you need a vent at the end of each main. Even one as small as the Hoffman #4A will make a difference on such short mains.

The fire in a coal-fired boiler burned all day, so once the air was out it stayed out. This is not the case with gas or oil. Proper main venting is the cure.

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Jay_11

No Hissing

Well, the contractor's view from what we have seen is that there are no main vents currently in my system and given the short lengths of runs of the steam mains, we would not see a big benefit to adding main vents.

He has since completed the steam boiler installation and once we replaced the air vents on all the radiators and he finished skimming the boiler and flushing the system of the MEX, there appears to be no hissing from the rads. The system is very quiet.

Can I take this as a sign that we are home free (at least until the future if it turns out there are main vents and they go bad and start leaking)?

Mark W

Sounds good

or maybe "not sounds" even better to me! :-)

Glad it's turned out well. I knew from your posts and descriptions you had found a someone good to get you up and running. No hissing, no swiss cheese basement ceiling, a well heated house, seems okay to me.

Now let's bring on the cold weather for a true test! I would never go as far as to say you're home free, Murphy's Law can never be escaped, but it seems that you're in good shape overall. Knowledge is your best ally, and you've gained plenty of it over the past few months.

Best of luck and best wishes to you, your family, and your house. Hope we've been of some assistance on the Wall, and don't hesitate to check back and post here when (and if) you need to!

Jay_11

Thanks to all

Yes, you and the folks on the Wall have been a tremendous help to me in getting my steam system replaced. The Wall really is an invaluable resource to homeowners like me--many times in interviewing a contractor who gave a questionable answer on one of the installation questions I asked from Dan's book, I came on the Wall to see if what he was proposing was an accepted practice or was cutting corners. More often than not, it seemed the latter. I was actually getting a little neurotic about the search for a capable contractor interviewing 10+ guys (since April!), and my wife was getting quite angry with me because I wouldn't pick one. To make matters worse, we have a nine-month old baby with a few medical problems, and the way it was looking, we were going to bring him back from his surgery at the hospital earlier this month to a house with no heat! Well the contractor we hired managed to complete the job the day we came back from the hospital and I'm glad I waited for him. System seems to work great so far. Virtually silent, even heating through the house, none of the explosion-like delayed ignitions we were getting last year, and although I can't swear to it yet--seems to be bit more fuel-efficient too.

Thanks again.