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Burnham water level fluctuation

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DaveG
DaveG Member Posts: 16
In one of my buildings we just had installed a Burnham V908A. There has abeen a lot of water hammer on start-up, which I think is due to the boiler constantly being over filled. Every day or so I go look at it, and it's over the top of the glass. Well, tonite I went down and the water started out at just over the high water line marked by the installer (about 1 1/2 - 2" below the top of the glass). I watch thru a few cycles, and what happens is that as soon as the boiler starts to make steam, the water level steadily goes down (there's a little bouncing, but nothing wild) and by the time the pressuretrol cuts out from high pressure, it's at or below the "low water" fill line (not the "normal low water: mark - the "low water cutoff" mark). This is 5 or 6 inches down from where it starts. When the boilers kicks off, the water level returns to the high mark or above. I think the reason it's constantly over filling is that often the automatic filler kicks in to "protect" the boiler during these cycles. Also, the amount of time the boiler takes to reach high pressure, and then go back to low pressure seems very short - only a minute or two - is this "short cycling"? The old boiler used to take much longer from when it hit high pressure till the pressure went down enough for the pressuretrol to kick back in.

Is this "normal"? How can I get the boiler to stop "needing" water, and thus overfilling, and then getting water hammer?

Comments

  • Dave

    There could be a number of reasons that this is occuring. But first we would have to know whether this is a one pipe or two pipe steam system, what the pressure settings are, if a two pipe system, whether a condensate receiver or boiler feed tank is being used and what type or model of control is maintaining the water level in the boiler. Has the boiler been cleaned out after installation to rid the system of oil and debris? Let me know and we'll come up with a reason why this is happening. I would suspect that you do indeed have a two pipe system and are not using a boiler feed tank and now have a misbalanced system meaning that the new boiler is making steam faster than the old, but your condensate is returning too slowly to maintain a proper water level during operation. If you are using a receiver, it may be turning on after shutdown to get rid of the condensate that is slowly returning with the end result of overfilling the boiler.

    Glenn Stanton

    Burnham Hydronics
  • DaveG
    DaveG Member Posts: 16
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    One pipe system. Was *supposed* to be cleaned after installation, but it's not like I was watching over their shoulder to make sure! What I can say is that even though the boiler is only about 1 month old, there is already a substantial build-up of "brown crud" at the bottom of the glass (bottom 2 inches can't even see thru?).
  • DaveG
    DaveG Member Posts: 16
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    Oh, and I think the cut in pressure is 1lb and cut out is 3 lbs (I'll try to remember to go down and look when I get a chance).
  • Really is unusual

    that this large a boiler is being used on a one-pipe installation Dave. What is extremely important here is whether the near boiler piping is correct in accordance with the manual and what model Low Water Cutoff is being used. Let me know.

    Glenn Stanton

    Burnham Hydronics
  • DaveG
    DaveG Member Posts: 16
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    System is probably around 90 - 100 years old, just new boiler, so 1 pipe wasn't a "new choice". Building is 3 150 year old row houses in Manhattan (12,000SF / 135,000 CuFt / don't know EDR but probably 40 radiators). I'll try to find the model of filler (where is that located on the filler?).
  • Steve Levine
    Steve Levine Member Posts: 106
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    I'll bet that the reason

    is mainly the lack of a receiver and feed pump. The old boiler was physically much larger than the new one. There was much more water in what we call the operationg range of the old one than the new. Even if it is firing at the SAME rate as the old, the water level is going down much more quickly because there is less water in that range. The feeder fills the boiler before the condensate can return, causing an overflow condition when it now shuts down.

    A receiver and feed pump (often better venting will speed the returtn enough to beat the feeder) will give this water a place to go on shut down without overfilling the boiler.

    This is basically true for ALL new steam boilers replacing old ones. It is not just a Burnham issue.

    Steve
  • Looking for model

    number of the Low Water Cutoff device. The problem you are having is most likely related to the limited amount of usable water for steam as compared to the old boiler. Today's boilers are much smaller than the old ones and thus have a much smaller water content along with the ability to make steam much quicker and efficiently. This can result in unbalanced conditions in regard to usable water in the boiler versus return rate of condensate. If condensate is slower to return than the usable water being sent out as steam, then you may have an water feeder kicking in to replenish it. When everything shuts down, the return water comes back and you now have too much water. A properly sized boiler feed tank is a great cure for this problem and the boiler will now get a pump control instead of a low water cutoff. All return water from the system gets piped into the tank, any makeup water will get made up into the boiler feed tank and the pump will only run when the boiler says it needs some water to maintain a proper operating level. These devices are very common on commercial pressure-fire boilers such as yours and are a perfect way to correct an unbalanced system. Hope this helps.

    Glenn Stanton
  • DaveG
    DaveG Member Posts: 16
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    The first thing I thought of when I saw that the boiler was over filling was what you describe: all the water goes "out into the sytem", and then the auto filler "makes up the difference" and then when "the chickens come home to roost", there's too much in the system.

    But now I don't think so because the water level in the boiler drops about 5 to 6 inches in about a minute or two. I just don't think there's any way that this much water is "boiling off" that quickly. And the pressure is building up really fast as well (as well as backing down really fast). My gut is that those two things have something to do with eachother.

    Also, the "old boiler" wasn't really "old" (about 6 years), and I don't think that the water capaicty is much, if any, different (If I remember correctly Weil-McLain ?58?).
  • Dave

    My concerns based on the information you have provided thus far is as follows:

    1.) How was the boiler sized - to existing boiler or to connected load?

    2.) How is the boiler piped - header, equalizer, etc.?

    3.) Most importantly ....... what happened to the previous boiler that it had to be changed this soon?

    All of these questions really need to be addressed before your original question can be answered. I would suggest contacting our representative in your area so that they may come out, take a look and help identify potential things that may be causing you problems. They will probably also want to speak with the installer of this boiler to point out what course of action needs to be addressed. Your contact in the NYC area is Venco Sales Inc. (631)754-0782. Let me know how you make out Dave.

    Glenn Stanton

    Burnham Hydronics
  • DaveG
    DaveG Member Posts: 16
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    1.) How was the boiler sized - to existing boiler or to connected load?

    Since I know that the installer did not get into the units before installing the new boiler, I can't imagine that it was done to the connected load. I'm assuming it was based on the old boiler output.

    2.) How is the boiler piped - header, equalizer, etc.?

    I looked at this stuff, and couldn't find any obvious gaffs, but.........

    3.) Most importantly ....... what happened to the previous boiler that it had to be changed this soon?

    Sections kept rusting out at the water line. The assumption is that there was too much new oxygenated water being added due to system losses, and this caused the problem. One section was replaced 2 years ago, 2 sections last year.... So the "boiler guy" convinced the building to replace the boiler (against my wishes to simply replace the remaining sections, and then try to find the "real problem" of where the system losses were occurring). But *this* problem (water hammer, boiler draining when making steam) definitely was not happening with the old boiler.
  • I strongly suggest

    to contact Venco Sales and your installer to identify and resolve this problem before the same thing happens again. My thinking is always toward a receiver storage tank w/ pump on the return side to balance out the supply rate / return rate problem and to make up the water into that tank instead of the boiler. This will require a pump control on the boiler but will definitely balance out the system. Makeup water will also blend with existing condensate in the tank and will be much less harmful to the boiler in general. This image is from McDonnell Miller and depicts the above scenario. Hope this helps.

    Glenn
  • DaveG
    DaveG Member Posts: 16
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    Ok, will do, but.....

    Is there any chance it just needs a good cleaning?
  • More than likely

    but the makeup water issue is not going to go away. The properly sized receiver tank will help in both aspects. Hope this helps.

    Glenn
  • DaveG
    DaveG Member Posts: 16
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    Sorry I didn't see this earlier, but as I said elsewhere, I'd bet that the water capacity of the "new" boiler is the same as the (6 year old) boiler.
  • DaveG
    DaveG Member Posts: 16
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    OK. I understand everything you are saying, but I still don't see why the water would be "leaving" the boiler at such a fast rate. Why is the level dropping 5 - 6 inches in only a minute or two? I understand how the tank solves the problem of a bunch of water coming back, but since this water currently does not appear to be "boiling off", but leaving for some other reason, will the tank solve *this* problem, or is it "just a good idea in general", but after installing it we may still have *this* problem anyway?
  • Two things going on here Dave

    First of all, you have a one-pipe system whereby the return side of the system is in contact with the boiler via the hartford loop connection. Depending on pressure drops through the system, you may always be pushing water back up the returns whenever you are making steam in the boiler. High pressure always goes to low pressure. This is happening above the Normal Water Level in the boiler, so you may very well have water in the horizontal returns in contact with steam. If you displace the water in the boiler back up the returns, the water level will drop somewhat. Add this to the fact that you will be boiling off about a 1/2 gallon of water for every 250,000 btus of boiler capacity, then you have 2 gpm turning into steam every minute on a V908A when you are making steam (1,110,000 btuh). Depending on the LWCO you are using and the level that it is mounted, you may drop off on low water every 5 minutes or less. Depending on your condensate return rate and or the boiler pressure dissipating allowing water levels to balance again, the water feeder may kick in at this time. If you happen to have a 47-2 or similar combination LWCO and feeder, the burner will continue to operate while the feeder feeds and water will stay backed up on the return side. This may cause an overfill condition at shutdown.

    By introducing a boiler feed tank on the return side, you have now eliminated the backup that occurs on the return side of the system. The feeder tank is piped to the boiler equalizer via small piping with a check valve. You will no longer be displacing the water level back up the returns. The only drop in level will be due to steamable water leaving the boiler as steam (2 gpm). If the pump control senses a drop toward minimums, it will turn on the pump, keep operating the burner and replenish again to operating range (about 1/2 gauge glass). If pump can't keep up and water continues to drop, burner will shut down. If tank level drops below it's minimums. makeup water will be introduced into tank by it's float valve.

    For now you can try lowering the pressure so less water is displaced up the returns and clean the boiler water. I don't think that it is neccessarily going to correct the excessive makeup water issue though. Hope this helps.

    Glenn
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,568
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    Glenn,

    with a one-pipe, gravity-return system, assuming it's sized according to the standard pipe-sizing charts where the pressure drop shouldn't be more than one ounce per 100 feet of travel, I would think that it would be extremely unusual for the boiler to push the water 28 or 56 inches into the return. Wouldn't you agree?

    I can see this with a two-pipe, gravity-return system, of course, and that may be what you were talking about here. Excuse me if I misunderstood. Thanks.
    Retired and loving it.
  • DaveG
    DaveG Member Posts: 16
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    I'm not trying to be "thick" or argumentative, but I do wish to be "clear":

    The water is starting to be "pushed out" of the boiler at around 2 pounds, which doesn't seem to be all that high (to me), and the 5 - 6 inch drop in water level takes about a minute, maybe 2 at max. So, from your boil off calcs, it certainly doesn't seem that this (boil off)is the thing causing the level drop. And I understand that the tank can make up for the drop and still not overfill, but it sounds like putting a band-aid on the problem rather than really "solving it", or is it "normal" for a boiler to have that much (5 - 6 inches of water) go out in a minute or so?
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,568
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    Wondering about a couple of things:

    Does this system have motorized zone valves?

    What starts and stops the boiler?

    Who sized it, and based on what?
    Retired and loving it.
  • Sorry about that

    My boo boo Dan. It is corrected. Thanks for the heads up. I was typing this while talking with my best friend who just lost his brother in the nightclub fire up here in RI Thursday evening. What I was trying to convey was not neccessarily what I was actually thinking.

    Glenn
  • DaveG
    DaveG Member Posts: 16
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    > Does this system have motorized zone

    > valves?

    >

    > What starts and stops the

    > boiler?

    >

    > Who sized it, and based on what?



  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,568
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    Sorry

    for your loss, Glenn.
    Retired and loving it.
  • DaveG
    DaveG Member Posts: 16
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    Does this system have motorized zone valves?

    No

    What starts and stops the boiler?

    Older "Heat Timer" (I'd post a link, but their site appears to be down right now). Blue faceplate, outside thermostat, amber light for "heating established", red light for "weather calls for heat" (or is that the other way around?, 24 hour clock dial, A thru I dials for amount of heat for night and day - know the one I'm talking about?

    Who sized it, and based on what?

    The installer sized it. As I said earlier, since he didn't get into the appartments, he couldn't have sized it on EDR. I'm assuming he sized it based on the old boiler.
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,568
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    Could be that he did

    size it that way, but may have added something for safety. This one sure sounds like it's either oversized or having a tough time dealing with the start-up oil and dirt.

    Any way to check the sizing by getting into the apartments?

    And thanks for your patience as we talk it through. I know these can be frustrating.
    Retired and loving it.
  • Dan Law
    Dan Law Member Posts: 59
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    Boiler water \"exiting\" to system

    Dave,

    Read through most of the posts, and seems like we’re getting off the practical
    side of things a bit. What I have up till now is that:

    1) Water rapidly leaves the boiler
    2) Your not sure how good the cleaning was, if any
    3) This is a retrofit boiler on a very old system
    5) There is a concern on boiler water volume

    My thinking is, if it looks like a duck, has webbed feet, and waddles when it walks,
    it's probably a duck! Sounds like to high TDS (total dissolved solids) to me, most
    likely in the form of crudola from the system. I take it your the building owner. If so, have the installing contractor come back & drain this puppy completely and refill
    (after cooling the sections of course) with clean water and refire it. If it settles
    down substantially, I think they've identified your mallard. You'll probably continue
    to bring back additional crud, but I'll bet the difference you see in the interim will
    be substantial.

    The near boiler piping is critical. This needs to be checked by the installing contactor in coordination with the rep Glenn mentioned (Ventco I believe).
    I also like "The Lobestael Method of Steam Boiler Water Quality
    Inspection" found in Dan's Lost Art book - really practical and a great
    troubleshooting tool. You and the contractor can address the possible low water volume issue
    AFTER you've got things to settle down. If your contractor has "Lost Art" (everyone
    involved in steam should) there’s a good section at the end on skimming and
    cleaning procedures, which is where I think your headded. I'll be interested to know your findings.
  • DaveG
    DaveG Member Posts: 16
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    If you're willing to have a lot of patience, and do some of the math, even though I can't get into the appartments I can do a lot from memory:

    Almost all of the risers have been covered by sheetrock soffits, except for 2 11 foot sections in one unit, and 2 11 foot sections in hallways. Altogether there are 12 risers, about 40 feet tall each. There are about 225 feet of horizontal mains running to these risers. Most of the "radiators" are the cheap, 1970's ?"finned tube"? type (aluminum, 1 1/2" core, fins about 1/8 inch apart, overall about 2 to 2 1/2 feet long by 4" wide, ?probably intended for hot water heat originally?, just like in a hot-water baseboard). There are about 30 of these ( so we have about 60 - 75 linear feet of this stuff?). Then, there are about a half dozen "smaller" cast iron radiators which are about 8 sections each, with sections that the loop is about 18" tall and 3" wide. Finally, there are 3 or 4 larger "industrial style" cast iron radiators which look like a "block-of iron", but obviously have sections. These are about 5 inches deep and about 2 feet tall each, and about 2 1/2 feet wide.

    I know this is a horrible description of the load, but it's the best I can do based on what I've got.
  • DaveG
    DaveG Member Posts: 16
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    Thanks, Dan. Just so you know, if I was coming up with my own theories by myself, that's what I think the problem might be. As I said, the boiler is less than a month old, and already the bottom two inches of the glass are already so brown that you can't see through. I'm pretty sure the guy has "Lost Art", since we talked about it once (I have it and read it), and he's on the "contractor list" here.
  • [Deleted User]
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    Sounds like you

    have an old EPA or a somewhat newer EPU Heat Timer. But, that is not the problem.

    My 2 cents. Sounds like nasty water, or high PH, combined w/ more input than required for the building. Now I will depart from what some of my learned friends teach.

    Not unusual to see 1 pipe steam systems in our area w/ net EDR's of 10,000 ft or more. We install many cast iron boilers to replace the 50+ year old steels. Always count the radiation. Then add a section(s) to the new boilers for water content. Always fire at, or sometimes a little below, the calculated load. Sometimes means using a burner smaller than what matches the boiler. Steams a little slower, but allows more time for the condensate to get back, before the feeder kicks in. Also reduces the surging and priming common in today's low water content pieces.

    It is possible that the old boiler's input was also at, or below, the actual load. Or. The old boiler's sections were coated w/ what fell out of all the fresh water, and did not transmit the heat well. That is what fresh water does to boilers, just before the sections let go.

    The crud in the bottom of the gage glass is what we expect to see after a few weeks. That means it is time to drain and flush the boiler and returns - again. Then we skim the boiler. Sometimes takes all day. We also pull and clean that bottom gage glass cock. It is the repository of the dirt the 47 or 51 missed. That, combined w/ the correct input, normally solves any problems.

    You should be concerned about the short life of the previous boiler. We have Weils, Smiths, & American Standard cast irons that saw the 60's. No boiler should die in 6 years. The old problem must be found and corrected.

    Suggest you find the leak, fix it, then try what I have suggested. Works for us. Might work for you.

    Happy steaming.
  • [Deleted User]
    Options
    Sounds like you

    have an old EPA or a somewhat newer EPU Heat Timer. But, that is not the problem.

    My 2 cents. Sounds like nasty water, or high PH, combined w/ more input than required for the building.

    Not unusual to see 1 pipe steam systems in our area w/ net EDR's of 10,000 ft or more. We install many cast iron boilers to replace the 50+ year old large water content steels. Always count the radiation. Then add a section(s) to the new boilers for water content. Always fire at, or sometimes a little below, the calculated load. Sometimes means using a burner smaller than what matches the boiler. Steams a little slower, but allows more time for the condensate to get back, before the feeder kicks in. Also reduces the surging and priming common in today's low water content pieces.

    It is possible that the old boiler's input was also at, or below, the actual load. Or. The old boiler's sections were coated w/ what fell out of all the fresh water, and did not transmit the heat well. That is what fresh water does to boilers, just before the sections let go.

    The crud in the bottom of the gage glass is what we expect to see after a few weeks. That means it is time to drain and flush the boiler and returns - again. Then we skim the boiler. Sometimes takes all day. We also pull and clean that bottom gage glass cock. It is the repository of the dirt the 47 or 51 missed. That, combined w/ the correct input, normally solves any problems.

    You should be concerned about the short life of the previous boiler. We have Weil, Smith, & American Standard cast irons that saw the 60's. No boiler should die in 6 years. The old problem must be found and corrected.

    Suggest you find the leak, fix it, then try what I have suggested. Works for us. Might work for you.

    Happy steaming.
  • butch
    butch Member Posts: 10
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    Cure-all for unstable water lines That causes steam boilers overfilling!!!! Check out Dan's The lost art of steam heating' PAGE 45 IT STATES THAT THE ANTI-SURGE TANK' SLOWS THE VELOCITY OF THE STEAM LEAVING THE BOILER AND LEAVES THE WATER IN THE BOILER WHERE IT BELONGS" CONTACT EVER-HOT ALL COPPER FOR MORE INFO@617-924-3877!!
  • butch
    butch Member Posts: 10
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    Cure-all for unstable water lines That causes steam boilers overfilling!!!! Check out Dan's The lost art of steam heating' PAGE 45 IT STATES THAT THE ANTI-SURGE TANK' SLOWS THE VELOCITY OF THE STEAM LEAVING THE BOILER AND LEAVES THE WATER IN THE BOILER WHERE IT BELONGS" CONTACT EVER-HOT ALL COPPER FOR MORE INFO@617-924-3877!!
  • butch
    butch Member Posts: 10
    Options


    Cure-all for unstable water lines That causes steam boilers overfilling!!!! Check out Dan's The lost art of steam heating' PAGE 45 IT STATES THAT THE ANTI-SURGE TANK' SLOWS THE VELOCITY OF THE STEAM LEAVING THE BOILER AND LEAVES THE WATER IN THE BOILER WHERE IT BELONGS" CONTACT EVER-HOT ALL COPPER FOR MORE INFO@617-924-3877!!
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,568
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    Butch,

    time to switch to the decaf.
    Retired and loving it.
  • DaveG
    DaveG Member Posts: 16
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    Dan,

    Sorry for "bumping" the thread, but I don't know if you saw my repsonse above this.
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,568
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    I missed that, Dave

    I'm not comfortable sizing these from here, especially since the size of the boiler is in question. I really think someone needs to be on the job, see these in person, and get the EDR as accurately as possible.
    Retired and loving it.
  • john_24
    john_24 Member Posts: 23
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    I agree

    that the boiler sounds like it needs a good cleaning but the fact that the old boiler was only 6 years old and going through sections bothers me. I would think that you might want to have a manufacturers rep look at the system. I wonder about the near boiler piping and also that if the old unit was oversized and when this one was installed an extra section was added now we have a big problem.
This discussion has been closed.