Steam system losing water.. a new question for an age old problem

sreja

In the last few years, with the fantastic help of Dan's books and the experts on this forum, I have gone through several major updates of the steam heating system in our 5 floor , 25000 sqft apartment building (build in 1929).



We have replaced every trap on every radiator (200+radiators), installed TRVs on every one.. skimmed the boiler, cleaned it, etc. and now have a tekmar 279 controller which makes a huge difference in terms smart heating cycle times.



It's an oversized Peerless 211A-8, but has modulating gas system so it can fire at different rates depending on pressure.  It run at between 1 and 2 psi.



The returns feed to a condensate tank and pump (and so return line is open to the air).



Now, the bottom line is that it heats the building wonderfully and it runs like a dream.



EXCEPT..



Except that a couple of weeks ago we cleaned out the boiler and tuned up everything, and I decided to replace the automatic water feeder with a VXT24 programmable water feeder that can measure how much water is being fed in.



What I'm seeing is an average los of up to 6 or 7 gallons PER DAY from the system, with weather in the 30s (seems to be worse when its colder and boiler running longer).



Needless to say I am losing sleep over this water loss in what otherwise seems to be a perfectly running system.



The steam guy and myself spend a couple of hours looking for any sign we could anywhere of where the water loss could be going.  I check chimney, flooded boiler looking for leaks, traced every return line i could see. NOTHING.



We cannot figure out where the water is going.



Now there are probably 100-200 ft of buried return lines under the lobby floor, which is thick concrete with no access.  these pipes do eventually emerge into the boiler room in a large pipe chase, with no signs of water.  and the pipes all look to be in good shape.



So now finally to my question.. Should i just let this issue go and stop losing sleep over it?  I mean *if* the problem was a leaking return buried in the concrete 200sqft tiled lobby floor somewhere, it would seem prohibitively expensive and insane to try to tear it up to get at it.  And there is no sign of the water, or any problems caused by it.



I hate to think of 7 (or is it going to jump to 15 when the weather hits 0 degrees?) gallons of lost water per day, and the oxygen effecting the boiler.



BUT i can't get a handle on how bad that really is for the system and for efficiency of it..



I mean is it a disaster to be replacing 5-10 gallons of fresh water a day into the boiler..  or is this something thats going to mainly just mean the boiler will die a year or two earlier than it would otherwise -- in which case economically it's probably better to just live with that then go chasing ghosts and tearing up floors.



I always seem to come to these questions on this forum.. i know what the IDEAL looks like (0 water loss), but it's so hard to figure out what is ACCEPTABLE, or cost effective..



Thank you in advance -- looking forward to reading your replies.!

nicholas bonham-carter

who moved my water?

i don't suppose the condensate tank could be discretely dumping a temporary excess of water from time to time. what would happen if you would close the inlet valve to the vxt24, so it could not add water to the system? could you see the waterline finally drop to a low-water state while you watched?

can you see both sides of the returns which run under the lobby? if they are a straight shot, you could always shove a copper line through the old iron pipe. if there is a leak under the floor, there is a risk of undermining the floor.

if it were not winter, you could cut the pipe, and get a drain inspection camera to have a look. or you could temporarily cap that line and put some air pressure in it to see if it would hold the air.

5 gallons of water is 6000 gallons of steam, which would surely be noticed somewhere in the building.

if the boiler is over-sized, then are you running at low fire most of the time? i would try to get that pressure down even lower. study the back-pressure during the venting on your 0-2 psi gauge to make sure you are venting at minimal restriction. good luck--nbc

sreja

re: Steam system losing water.. a new question for an age old problem

Hi nicholas.



You say:

"i don't suppose the condensate tank could be discretely dumping a

temporary excess of water from time to time. what would happen if you

would close the inlet valve to the vxt24, so it could not add water to

the system? could you see the waterline finally drop to a low-water

state while you watched?"



Not sure what you mean by discretely dumping, but the condensate tank/pump is only a few gallons and there is no where for it to put water except into the boiler.  and yes i can confirm that the vxt is only adding water because the boiler runs out of water (in fact the nice thing about the vxt is that you can set delays so that it will only kick in if the boiler is calling for water for 10 minutes straight).



And I can confirm that it's not simply an issue of a long delay in condensate returning to the boiler since this daily water loss happens every day for weeks.



---



Regarding your suggestion about copper pipe inside the old pipe -- that's a fun idea but i'm afraid i didn't describe well the return line under floor situation -- it's not just one pipe its probably half a dozen pipe leaving ground floor radiators up to 100 feet away all probably converging at some point under the concrete lobby floor and then tieing to a large pipe that enters the boiler room.  that would make capping the pipes and trying to pressurize with air fruitless i think..



i think trying to use a drain inspection camera sounds like a good idea to me.. i think that may be the approach to take after heating season..



---



the system spends most of its time at full and medium fire, then a little bit of time at low fire, which tends not to hold pressure.  regarding running at less than 2 psi.. you've suggested this to me before.. it sounds worth trying but i'm still not sure why it would be such a good thing -- would it really make a big difference to anything (efficiency, etc.) if i could get it down to 1psi?

Dave in QCA

Condensate loss is serious

The condensate loss that you are describing is most likely occuring in the burried piping that you describe under the lobby.  Burried iron piping is a common problem and the deterioration of buried pipes seems to be worse than wet returns that are not burried, and certainly much worse than condensate return lines located above the water line.



You really need to do further investigation and determine where the leakage is occuring and it needs to be corrected.  In my mind, I am imagining a grand lobby space with a ceramic or porcelain tile floor on concrete.   If so... Ugh!    If it is otherwise covered, than the destruction will be less.  You may be able to find a new way to route the condensate lines that does not require them to be burried... but all of this requires investigation and study, and we don't have the advantage of being able to visit your building.   Perhaps one of the pros is near enough to be able to do some consultation.



Condensate loss is a serious matter because it will destroy your boiler.  You do have the advantage of having a boiler with a pretty good water content, that being 63.3 gallons.   But, if you're having to add 6 gallons a day, that is 10% of the water.  In 10 days, you will have replaced all of the water, but the minerals and chlorides from the lost water are still in the boiler, resulting in a mineral and chloride level that is twice that of fresh water.  In another 10 days, it will be 3 times, 10 more days it will be 4 times, and so on.   It is not so much that fresh water is bad, but rather the result of continually adding fresh water because of the loss of steam or condensate.  If this is not rectified, it will destroy your boiler.  Depending on the chloride level, it can drastically shorten the life of the boiler, causing rot at the water line.



This brings up another possible point where the water is being lost.  Have you removed the draft hood or other inspections plates to examine the cast iron sections of your boiler.  It is possible to have a leak above the water line in the boiler and if so, you would be losing steam up the chimney.



Assuming that the leakage is occuring in the buried lines, (which you need to confirm) I would recommend an interim measure similar to that used in controlling mineral levels in process boilers where a large amount of steam or condensate is routinely lost and where makeup water is high.  This is accomplished by continuous skimming or blow down so that hi mineral/chloride containing water in the boiler is dumped and replaced with lower mineral/chloride content makeup water.  In your case, dumping 1-2 gallons of boiler water every day.  This is equal to the amount of condensate being lost and will keep your dissolved mineral and chloride level in check.  The level will be higher than that of the makeup water, but it should come to an equilibrium and not continue to rise.

sreja

re: Steam system losing water.. a new question for an age old problem

You asked: "This brings up another possible point where the water is being lost. 

Have you removed the draft hood or other inspections plates to examine

the cast iron sections of your boiler.  It is possible to have a leak

above the water line in the boiler and if so, you would be losing steam

up the chimney."



I can confirm that we filled the boiler up to the pressure relief and checked for leaks in the boiler and found none.  there is also no sign of water vapor in the flue..



----



The idea of solving the problem of too much fresh water being added by draining out and adding even more water so counter-intuitive to me..  However the idea of somehow treating the incoming make up water is intriguing.  If it is economically infeasible to tear up the lobby floor and find and fix a leaking return.. i wonder if there might be an economically feasible way to treat the incoming make up water to make it less harmful to the boiler?

sreja

re: Steam system losing water.. a new question for an age old problem

I'm currently thinking that the best/only thing to do is wait for warmer weather and then try to use drain/snake camera and try to get it into the return lines that seem to travel below the floor, and at least try to locate a leak location.



Has anyone had any lucky using a FLIR camera to find such leaks?  Unfortunately we are talking about an extremely thick and tiled/carpeted floor.

Dave in QCA

The process of elimination

So, if you can confirm that there are no leaks or loss occurring in all of the piping that you can see and not occurring in the boiler, it seems that it only leaves the buried piping as a possibility.

Dave in QCA

Investigate, monitor, and plan

Yes, it sounds like it is not a good situation.  I have seen similar situations and the corrective measure involved removal of flooring materials, saw cutting the concrete, opening up the trenches, removal and replacement of all of the piping an fittings.  It is an unfortunate situation.

In the meantime, I would investigate and plan for the repairs.  I would not attemp them during the heating season.  But, during this heating season, I would very carefully monitor and control the mineral content in your boiler by the action I describe in previous post.

Long Beach Ed

Losing Water

I recently posted about a small residential system that lost three to five gallons of water a day. 



The majority of the steam was escaping, unnoticed from one lose radiator union. 



It was a Sunrad radiator with the union sidways over a storage room.  Any leaking water went unnoticed and the steam was so dry, it was completely undetectable in the large bedroom. 



It blew like a whistle when we pressurized the system with 5 pounds of air. 



Lot of unions in your building!   

nicholas bonham-carter

treating boiler water

what about putting a reverse osmosis filter on the incoming water line? the output is like distilled water, i think.--nbc

Dave in QCA

Distilled and RO water bad for boiler

Nick,  While it sounds like a good idea, distilled or RO water, or any water that is totally free of any dissolved solids is bad for a boiler.  The reason is because when the water is that pure, it is more aggressive toward metals and will cause the metals to dissolve into the water faster than water that has some, but preferably a small amount of mineral content.  Also, in an heating steam boiler where steam is not maintained, and the condensate is continually mixing with the atmosphere and taking in CO2 and O2, there is no way to completely eliminate oxygen corrosion.  Oxygen in otherwise pure water will be more aggressive than normal water. 



Some process boilers are set up to run on RO water, but it is necessary to add other chemical additives to the water and the levels must be maintained carefully on a continuous basis.   This involves running a series of chemical analysis tests on a daily, or more frequent interval.

nicholas bonham-carter

ro water

might still be ok in this case as the inside of this boiler may have lots of minerals to temper the ro water. maybe we can make a test for the effect of ro water on cast iron in general.--nbc

nicholas bonham-carter

leaking returns

here is a thought on this, could the radiators in the effected area [in the lobby] be replaced with hot water radiators, and fed with new lines above the floor from the boiler as a hot water loop? this would save the digging up of the floor.

i know you said the boiler was a bit over-sized, so maybe some hot water could be made with it as well to use up those surplus btu's.--nbc

sreja

re: Steam system losing water.. a new question for an age old problem

I suppose that would be a theoretical possibility, but with these thick plaster walls and ceilings, doing any work on the buried pipes is extremely expensive.  and it's probably the entire 5 floors of the building in that area that feed into the return lines that go under lobby floor.



But your suggestion really brings me to the very heart of the question that i was trying to ask here:



I know it's bad to add "excess" make up water into the boiler because it contains excess Oxygen which is not goof for the boiler.



But I don't how *HOW* bad.



I don't know when the most cost effective solution is simply to live with the excess make up water



Let's say it turns out that in worst case scenario we add 8 gallons a day of make up feed water.. What kind of figure should I put on the damage done by that?  I mean if that ends up costing as much as say an average of $500 a year extra in terms of a decrease in boiler efficiency and shorter boiler lifespan, then it's still probably smarter to live with that then try to spend $10,000 to try to tear up and find and fix the leaking return..



On the other hand.. if a loss of 8 gallons a day means that we are going to lose half the life of the boiler and thus cost us an averaged $1,000 a year AND result in an almost guaranteed catastrophic failure 5 years down the line and worsening leakage.. well then we need to treat this more seriously.



I can tell already what my steam heating guy thinks -- he thinks it's not so horrible a loss of water, and that we shouldn't overly worry about it.



At this point, my pride is egging me on to fix the problem, since everything else works so well in our heating setup -- but my logical mind is telling me that we may be reaching the point where it's best to just let this go and live with it -- as much as that may go against the instincts of those of us who have read Dan's books



Any thoughts on that from those of you with long-time hard-won steam experience?



(thank you everyone for all the advice so far -- it's so comforting to be able to talk to you guys about this stuff!)

Long Beach Ed

Damage

The damage caused by excess make-up water is too subjective to calculate.  It depends on many variables:  Water quality, casting quality and design, metallurgy, and operating temperatures.  



Some boilers are very tolerant, others are not.  Some water eats boilers, other water is not as aggressive.  Even the temperature of the returning condensate plays a role.



And don't expect much help from the manufacturer, though a plumber familiar with the area's misshaps may help form an estimate.



We operated a Burnham Jubilee boiler that was installed in 1964.  They were known to rot out at their water lines when subjected to lots of fresh water -- so much so that a Burnham rep said their nearly bankrupted the company back then.  Ours was taking on five gallons a day -- lots for a 200,000 BTU unit.  When we removed it this year, the sections showed no erosion whatever.  It was like new. 



Good water.

Mike Kusiak_2

NYC water

From what I understand, NYC treats their water supplies with orthophosphate, to reduce the leaching of lead from the old soldered joints of copper piping in homes. This has the added benefit of decreasing corrosion in boilers and water heaters also.



I have noticed that tank type water heaters seem to last much longer than before the treatment began years ago.

sreja

re: Steam system losing water.. a new question for an age old problem

I've never put any chemicals in the boiler, even when cleaning.



But if we end up living with 10+ gallons of make up water every day, might there be some chemicals we should add to reduce the harmful effect of oxygen?

Jean-David Beyer

might there be some chemicals

I am not a professional, so this will not really help you. My guess is the answer to your question is NO. I knew some people who operated steam railroad locomotives. These are essentially open systems in that make up water is continually supplied, and the steam produced, after running through the cylinders eventually escapes up the stack into the air.



What they do is analyze the boiler water every day, and add stuff to protect the boiler. They use sodium sulfite to scavenge the oxygen, tannic acid for something, sodium hydroxide to control the pH, and something, I forget what, else. But you cannot just add it and forget it. They test the water to determine how much of each to add. And they blow down the boiler (big valve at the bottom fo the boiler) every day to get rid of some of the chemicals that build up.  I cannot imagine a homeowner doing all this, or even having a pro come out on a regular basis to do it.



Watching them blow down the boiler is exciting. I do not know what the temperature of the water is, but it is at about 150 PSI, and it flashes to steam as it comes out the pipe. And I mean steam, not the cloudy water vapor that appears several feet past the end of the pipe. I just checked: 365.9F.

Mike Kusiak_2

Blowdowns

I would follow Dave's advice of regularly draining an amount of water from the boiler to prevent the buildup of minerals. As he mentioned, this is standard procedure for boilers which use large amounts of makeup feedwater.



As long as the makeup water is boiled after it is added, most of the oxygen will be driven out of solution. Remember that you have a system open to the atmosphere, and there is always some oxygen present. Since oxygen's solubility in water decreases with temperature, it is being constantly being driven off when heated and partially reabsorbed as the cooler condensate returns. So there will be a fairly constant amount of oxygen in the system regardless of whether you add makeup water or not.



Unless you constantly monitor the water chemistry by testing, adding chemical treatments can do more harm than good. The compounds involved can be corrosive themselves unless their concentrations are kept at precisely the right levels.

sreja

re: Steam system losing water.. a new question for an age old problem

I went and read up a little bit about blowing down water regularly to remove minerals in the boiler.. fascinating.. It does seem to be a real thing, and it seems to me that we may have caught the "great one" (Dan Holohan) in an error of omission in his heating books!



I say that because at least in "We Got Steam Heat" (the larger book is down in my boiler room), Dan mentions blowing down the boiler as *soley* to clear out crud from building up in, and damaging the LWCO.  And does not even mention the concept of blowing down a boiler in order to remove minerals and stuff in the boiler itself.

Dave in QCA

Its a subject for a different application

I will jump up to defend Dan.

He many times will mention a factor that is common place in process boilers, and say that is the way it is in a process boiler, but not in a heating boiler.

Thus, the point with heating boilers is, you're not supposed to be losing condensate and you're not supposed to be losing steam.  If that is the case, then your make-up water will be VERY small, and you will not have a build-up of minerals in the water.  He repeatedly warns against the perils of having high makeup water and advises to correctly the problem.  He is correct.

sreja

re: Steam system losing water.. a new question for an age old problem

Don't get me wrong -- I was just poking a little fun at the man who I consider to be the god of steam heating, whose books I have read religiously..  But I do think that it would not have hurt to at least have mentioned when discussing blowing down boiler/LWCO the issue of other reasons that one might blow down a boiler -- if only to explain why with steam heating it's probably/usually not necessary.

Jamie Hall

Oar waving...

Just my two cents worth; it is quite correct that boilers which are intended for consumptive use of steam (process boilers, for example -- or the ones I'm familiar with, steam locomotives!) need to be blown down to reduce mineral buildup.  Heating boilers should be non-consumptive, so they shouldn't.  You  with your little nightmare are somewhere in between -- so yes, you probably do need to blow down now and then.  It will reduce the tendency to foam and prime as minerals build up.



That said, however, you want to blow the boiler down for that purpose from a proper blow down fitting which, hopefully, you have somewhere near the base of the boiler.  Not that you don't want to blow down the LWCO too; you do, but that's different.  What you are trying for here is to get a reasonable amount of the crud out of the boiler -- not the LWCO.  But don't get carried away.  No need to blow until it runs clear... but beyond that, I can't advise you.

sreja

re: Steam system losing water.. a new question for an age old problem

Thanks Jamie -- that makes sense, and yes we have a port at the base of boiler we can drain from.