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LWCO adding water each every cycle

gfrbrookline
gfrbrookline Member Posts: 683
edited January 2017 in THE MAIN WALL
I have a 1 year old Burnham V904 steam boiler, single pipe steam, NG Beckett burner. The vaporstat set at 16oz cut out and 12oz subtractive cut in. The boiler will run for about 20 minutes, the water level in the site glass goes up from 2/3 to full and will bounce up and down between full and beyond where I can see it for about 12 minutes then as pressure starts to build it will level off and slowly go down to about two inches above the LWCO line. Once the vaporstat trips the water level drops to about a half inch below the LWCO and it starts to add water until it hits the line, 10 seconds or so, and the boiler will kick on and run in 1 to 2 minute intervals on pressure 1 or 2 times before the tstat is satisfied. Every week this amounts to about an inch of water above the 2/3 mark that the installer put as the sweet spot. I reset it when I blow out the sludge from the LWCO each week. Is this normal or should I worry about the added water each cycle. My last boiler died after 10 years because of a carbonic acid so I want to make sure it doesn't happen again.

Comments

  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,510
    Your boiler may not last even 10 years if it continues like this.
    A normal, well piped, and sized boiler should have a stable (within one inch) waterline while firing.
    I would suggest some skimming (do a search here) is needed to make sure the water is clean. Any additives should be drained out, and pure water added back in.
    You probably also need more capacious main (not rad) venting, so that less pressure is needed to push out the air at the beginning of the cycle.
    In the meantime, valve off the auto feed, so your introduction of fresh oxygenated water is stopped, making sure the LWCO functions as it should to cut off the burner when the waterline is too low, as I am sure the water will come back, unless you have a leak.
    Post some pictures of the boiler, and its piping, so that any improper installation can be ruled out as a cause of the water leaving the boiler.--NBC
  • gfrbrookline
    gfrbrookline Member Posts: 683
    My mains were calculated at 1.5 cubic feet each so I think that 1 bigmouth per main should be good, I can always add more if needed.

    I had my contractor come out today to fix a sagging riser and he spotted that I had the LWCO feed valve shut off and I told him what was happening. He told me that I just had slow returns. He also saw the big mouths and asked me who told me to put steam traps where my vents should be. He was a little blown away by the concept but when he felt the air moving out of them he thought they were great.

    I will try skimming it this weekend.
  • Fred
    Fred Member Posts: 8,518
    It sounds like skimming is definitely needed. I'm willing to bet that if you do a very good, slow skim, (it may take several over a few weeks) that you just may find the need for those TRV's, in your other post, will be minimized. Oils on the surface of the boiler water make it very difficult for the steam bubbles to break through the surface of the boiler water and can push water back into the wet returns. Strange things happen when oils are introduced into a steam boiler and a relatively new boiler should be skimmed until the water in the sight glass is stable (maybe 1/2 to 1 inch bounce and no moisture on the upper portion of the sight glass).
  • Abracadabra
    Abracadabra Member Posts: 1,948
    If returns were slow like your contractor is saying, the LWCO adding water every cycle would eventually cause the boiler to flood when all the condensate came back slowly. If the boiler flooding?
  • gfrbrookline
    gfrbrookline Member Posts: 683
    not flooding but it does creep up about an inch every 3-4 days
  • KC_Jones
    KC_Jones Member Posts: 4,840

    He told me that I just had slow returns.

    Did he offer a solution for this? Returns on a typical residential system shouldn't be slow by design. Did he suggest cleaning them out? Checking pitch on any returns above the water line?

    I agree with the others the performance sounds like more skimming is needed.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • Abracadabra
    Abracadabra Member Posts: 1,948

    not flooding but it does creep up about an inch every 3-4 days

    That means that after a month your boiler should be flooded.
  • gfrbrookline
    gfrbrookline Member Posts: 683
    Just had it skimmed yesterday, hopefully that will fix it.
  • New England SteamWorks
    New England SteamWorks Member Posts: 1,429
    You should not be cycling on pressure the way you describe. Do you have a Cyclegard and is it cycling on that rather than pressure?

    If you have a VXT feeder, which you should, you can program a delay before it feeds to allow water to return.

    I do recommend pictures of your boiler and it's piping be posted here. Something seems amiss.
    New England SteamWorks
    Service, Installation, & Restoration of Steam Heating Systems
    newenglandsteamworks.com
  • gfrbrookline
    gfrbrookline Member Posts: 683
    I have 2 MM LWCO's one with a feeder and one without. Since the boiler was skimmed yesterday it runs steady for about 30 minutes with minimum pressure, once all of the vents close it shuts down at 14 oz. Once the pressure drops it kicks on and runs for abut 2 minutes until the Tstat is satisfied. Ideally I would like to eliminate the 2nd 2 min cycle.

    Both of my mains have Big Mouths which should be more than enough to handle 1.5 cubic feet of mains and the building heats evenly after many years of tinkering. Cant say enough about Dan's books and this site. I cut my heat bill by $4K, 50%, this year.
  • Fred
    Fred Member Posts: 8,518
    What is the Sq. Ft. Steam rating on the boiler plate? What is the total connected EDR? It is very likely the boiler is over sized for the connected EDR. If so, you should have a Pro look at it and see if it can be down fired to bring it closer to the EDR and eliminate any short cycling.
  • gfrbrookline
    gfrbrookline Member Posts: 683
    I know I am oversized by about 25% if not more. The top floor unit on the cold side of the building sold right after we put the new boiler in and the new unit owner took the radiators out and replaced them with split units, without permission, and we have little recourse. They had split units where they came from and wanted nothing to do with hot radiators and no AC. By the time we knew they did it the old radiators were in the basement.

    The burner has been downfired as much as possible and the increased main venting has helped a lot with short cycling.
  • Jamie Hall
    Jamie Hall Member Posts: 17,111
    I doubt very much that you can eliminate that pressure cycle at the end of a run, since you say that you have downfired as much as possible. It's not going to really hurt anything, taken by itself.

    However. You also mention that the water slowly creeps up. Not good. If it is creeping up because the auto feeder is adding to keep the LWCO from tripping...

    A question: are there any returns which are close to the water line (within 28 inches), but above it? If so, they may be your problem. They should be relocated to either by definitely dry -- or definitely wet.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • gfrbrookline
    gfrbrookline Member Posts: 683
    All of my returns are about 36" above the waterline before they make the 90 degree turn down.

    I have had the LWCO turned off for 5 days now and had to add about 2 gallons of water. I have no evidence of leaks anywhere in the system, all of the floor valves and air vents were replaced last year when we replaced the boiler to balance the distribution out.
  • Fred
    Fred Member Posts: 8,518
    If you've had to add 2 gallons of water in the last five days, you probably have a leak of some kind. A vent that is not closing, a valve that is leaking/steaming around the stem, a union on a radiator or pipe that leaks. Two gallons in five days is about 12 gallons a month. That water is going some where.
  • Abracadabra
    Abracadabra Member Posts: 1,948
    JMHO, but I don't think "about" 2 gallons in 5 days is that huge of an amount. V904A is 1508 sq.ft. steam.
  • Fred
    Fred Member Posts: 8,518
    I wouldn't want my boiler to use 12 gallons of water a month. Seems like a lot to me.
  • gfrbrookline
    gfrbrookline Member Posts: 683
    I am probably blowing 5 gals out of my LWCO's when i drain the sludge out of them each week. Should I not be flushing these out that much? I purge them until the water runs mostly clear.
  • Fred
    Fred Member Posts: 8,518
    If you have a float type LWCO, like the McDonnell Miller #67, you need to blow them down until the water is clear but that shouldn't take 5 gallons. I have to blow mine down weekly also (MM#67) but it only takes between a quart and, at most, 2 quarts. It sounds like your boiler and wet returns need a good flushing and cleaning.
  • gfrbrookline
    gfrbrookline Member Posts: 683
    How do you flush out the returns? If I turn the faucet on the bottom of the wet returns the water that runs out is clear. The boiler was just drained three months ago when it was serviced.
  • Jamie Hall
    Jamie Hall Member Posts: 17,111

    How do you flush out the returns? If I turn the faucet on the bottom of the wet returns the water that runs out is clear. The boiler was just drained three months ago when it was serviced.

    That's the way to do it -- but you shouldn't have to do that more than twice a year, if that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • gfrbrookline
    gfrbrookline Member Posts: 683
    edited February 2017
    So why would I be getting so much gunk in my LWCO's each week? Should I stop after the initial brown water stops and not worry about the brown blotches that come out every few seconds? The water in the site glass is always clear.
  • Fred
    Fred Member Posts: 8,518
    If the water that runs out of the wet returns is clear and the boiler was drained three months ago, you shouldn't have to drain five gallons of water out of the LWCO before it clears up.
  • gfrbrookline
    gfrbrookline Member Posts: 683
    That's 5 gal total, 2 LWCO's.
  • Fred
    Fred Member Posts: 8,518

    That's 5 gal total, 2 LWCO's.

    What model LWCO's do you have? Some of the bigger ones may take a gallon to clean them out. If it is the McDonnell Miller #67, I would expect no more than a half gallon each.




  • gfrbrookline
    gfrbrookline Member Posts: 683
    One is a no. 63, the one with the feeder is a 247
  • Fred
    Fred Member Posts: 8,518
    Probably a gallon each blow down. They are larger than the MM #67. I just looked at the Manual for the #247, it just says blow down weekly while in operation. Doesn't suggest estimated water amount for blow down.
  • gfrbrookline
    gfrbrookline Member Posts: 683
    Thanks, i will cut back to the initial brown purge.
  • Fred
    Fred Member Posts: 8,518

    Thanks, i will cut back to the initial brown purge.

    There are strainers/filters in the water feed attached to those LWCO's too. They should be taken out and cleaned or replaced annually. If they get clogged, that may be why you are seeing them add more water than you need and raising the water level in the sight glass. I think there are a couple gaskets that have to be replaced when the strainer/filter is cleaned so don't take it apart until you have what you need.
  • gfrbrookline
    gfrbrookline Member Posts: 683
    I watched the boiler tonight and may be over thinking this.

    The boiler ran for about 40 minutes and cut out on low water. The pressure never rose above 12 oz on a 1-3 dial.

    It kicked back on after about 90 seconds and ran for another 12 minutes before the T stat was satisfied.

    Could I be over venting the radiators? The building is balanced as far as temperature but I have varivents on the cold side and ventrite #1 and honeywell TRV's on the top floor of warm side or the building. We are a corner building so one side has considerably more exposure to the elements. I know the varivents have a reputation for spitting steam and the people who live in these units probably wouldn't notice if they did. Should I swap them out with more ventrites #1 or hoffman 1A's. I put the varivets in so they would heat up fast but am now thinking they may be the source of my water loss. I am guessing since I installed big mouth vents on the mains the building will heat evenly without the varivents.
  • Fred
    Fred Member Posts: 8,518
    Varivents do tend to vent to fast. If they are spitting steam or water, I would replace them. I think the vent-rites are a good vent. I use and have had great luck with the Hoffman 1A's but some of them can click as they open and close and, to some, that can be irritating. I only have one that clicks, on the smallest radiator in my house so I don't know if radiator size plays into that anomaly or not.
  • gfrbrookline
    gfrbrookline Member Posts: 683
    So this years update

    Had New England Steam Works service the boiler this year. He massed out my main venting, 3 big mouths on the long main, 2 on the short, one one the long drip return and a G2 on the short, very well balanced. He also flushed the boiler and mains.

    I switched to an assortment of Gorton vents, 4's on the hot side and small radiators , 5's on the 1's floor of the cold side and C's on the 2nd floor large radiaors, 5 on the bedrooms. The 2nd floor has newer windows but are much draftier than the rest of the building and tends to be 3-4 degrees cooler. I don't want to add larger vents as I don't think it will fix the problem, the unit owner just needs to replace the windows.

    The main venting and Gortons have balanced the heat in all but the old window unit. The water level in the boiler is stable within 1/2 inch and has not been cycling on water or pressure. I do however have to drain about 2.5 gallons each to get the water clear from the LWCOs. The term blow down makes me wonder if I am doing something wrong. Should I be flushing them when the boiler is running and at pressure as opposed to when it is resting?

  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,510
    Blowing down a float LWCO while running will make sure the burner cuts off on low water as it should.—NBC