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My Garn Corrosion Fiasco Part 1

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Rick Stanley, Feb 6, 2011.

  1. Hydronics

    Hydronics Feeling the Heat

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    Guys, if the 190* temp is critical, why not use an aquastat to kill the fan when the water hits 190* even if the unit still has wood left?

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  2. Willman

    Willman Minister of Fire

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    Thanks Rick for bringing this to the forefront. Another plus on the Garn side is actually being able to look in and do a visual inspection. Without your observation a lot of people wouldn't have even gave water quality a second look. Now how would one do an inspection of a closed systems boiler to check on the integrity of the metal? Send a tiny camera thru the water tubes like the sewer and well bore cameras?
    Will
  3. Singed Eyebrows

    Singed Eyebrows New Member

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    That might turn a clean burning Garn into a "smoker". I hope that the water treatment gurus can come up with something bulletproof, Randy
  4. heaterman

    heaterman Minister of Fire

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    That is totally contrary to the design and operating characteristics of a Garn. Once the wood load is going it never shuts down. No cycling = clean burn= very good efficiency=lower wood consumption.
    People would start using it like any other boiler. By that I mean loading it full and just letting the aquastat cycle the air flow much like an OWB. Due to the nature and design of the heat exchanger tubes in a Garn, idling is something to be avoided at all cost.
    My advice to people who are running a Garn is simply to avoid firing the thing unless water temp is below 170*. The top temp will finish around 190-200 unless a person has severely over loaded the unit.
  5. Como

    Como Minister of Fire

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    and if your boiling point is 195F?
  6. heaterman

    heaterman Minister of Fire

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    Adjust accordingly.
  7. bpirger

    bpirger Minister of Fire

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    Well, I have to agree with heaterman that there is no need for panic...we all just have to observe and keep an eye on things. The Garn manual says 9% of units are affected by corrosion...and most of these have been bacteriological in nature.

    That said, I just read the Operation and Maintainence manual, Revision 8, Dated April 2010. The only mention of firing temp I see is that wood should not be added over 185 as this may lead to overfiring...and overfiring to 205 routinely may cause excessive wood usage. No where did I see any mention of 190. Certainly it says bio corrosion is an issue to watch and bio corrosion can do very significant damage in just a couple of months. " Bacteriological corrosion is highly unpredictable; however, once active it can corrode through a tank in a few months. As indicated in the past, visual inspection, periodic testing and peridodic cleaning coupled with ongoing chemical treatment is one of the mostg effective programs for corrosion prevention."

    EDIT: The installation manual says to fire the unit to 190-200 degrees to get the water to expand and overflow through the overflow pipe...to assure the water level is correct. Once this happens, presumbaly it will never happen again (unless water is added or fired to a higher temp). No indication of a 190 limit at all.

    Nothing relates firing temps to bio corrosion.

    I think the 190 must have been thrown out there, but it sure isn't in the manuals. Certainly not related to critter creation....

    So I guess we just observe. Is there any downside to a biocide treatment (from Precision) EXCEPT the cost? Mayve once a year, for the non heating summer say? DO NOT EVER USE CHLORINE.

    The manual does say: Add the recommended biocide at the following times: whenever makeup water is added to the unit; a few days before the end of the heating season; and at the beginning and/or middle of the heating season. Dusty or dirty locations require more frequent biocide additions to minimize sludge build-up and under deposit corrosion potential." Presumably the recoomendation comes when there is a positive test for bacteria.

    Why not as a prophylactic?
  8. TCaldwell

    TCaldwell Minister of Fire

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    As the bottom of the tank is coated , for corrosion protection why can't the the balance or at least the top 1/4 also be with the same product? It seems that the chemicals precision reccomends must be compatable with the coating that comes on the bottom already. With proper surface prep, more covered area, maybee less damaging potential.
  9. jebatty

    jebatty Minister of Fire

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    Excellent information for Garn owners. Yours is the first post in this thread showing what is in the Garn manual.

    Based on this information, nearly 1 out of 10 Garns experiences corrosion. Perhaps Garn owners could report on what they find or have found 1) if they have rigidly followed the inspection and treatment procedures and recommendations, or 2) if they have not followed those procedures rigidly, undertake an inspection at the end of this heating season and report, and then do what needs to be done. A Garn, or any other boiler, is far too big of an investment to suffer the risk of premature corrosive failure, especially because the 1 of 10 for Garns is a clear warning that the risk is not remote.

    Although Dectra has little reason to consider my input, given Rick's experience and all the traffic on this thread and other Garn threads, it might make good business sense for Dectra to put out a notice to Garn owners reminding them of the need for inspection, proper water treatment, and corrective action if corrosion is discovered.

    It would be good advice to all wood boiler owners to inspect their boilers. I also will do an inspection of my Tarm, to the extent possible. It has an access hatch on the top for insertion of a coil heat exchanger, so by removal of this hatch some limited inspection of the interior of the boiler should be possible. I don't recall, and a quick review this morning did not discover, anything in the Tarm manual regarding the testing of fill water or maintenance of any type of water condition, although the warranty does not cover damage from the effects of corrosive water supply. I haven't given much thought to the warranty because I did a self-install, and the warranty only covers installs by a qualified contractor whose principal occupation is sale or installation of plumbing and heating equipment, and the warranty requires service and inspection every two years by a qualified service person. I would assume that my self-install and no inspection by anyone other than myself might cause some resistance on the part of Tarm to any warranty claim. This is my 4th heating season of a 20 year warranty period on the boiler body, so I've survived 20% of warranty longevity already. And this is getting pretty close to "payback" from money saved by not having to buy electric heat or a propane boiler and fuel, although I would not like to buy another boiler.

    I did discover in the manual a statement to use wood with MC of 15% or less "for best operation." 20% has been my assumption, although my wood is 2 or more years dry, covered from rain/snow but open to the air, and every time I put my Wagner lumber moisture meter on a re-split piece I read MC usually under 10% and always less than 20% (probably less than 15% but less than 20% is what I've looked for).

    And for all boiler users, maybe a careful re-read of the manual is in order. Surprises might be the result.
  10. TCaldwell

    TCaldwell Minister of Fire

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    If you look on garn tech specs, under btus stored they use the range of 120-200degf, should this be reviewed if there reccomendation does not exceed 190degf.
  11. jebatty

    jebatty Minister of Fire

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    This thread is now a hit on Page 2 of a *oogle search on "bacteriological corrosion." The world is now a party to this discussion.

    A short description of bacteriological corrosion and the environments in which this can occur:
    Bacteriological Corrosion
  12. Fred61

    Fred61 Minister of Fire

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    Although research on this should be left to the experts and I'm not sure if anyone has identified the bacteria that is the culprit in this reaction, I just wanted to note that over the years I have had some luck using copper sulphate for treating water. Back at my former place, I used to treat my pond with it to reduce the microscopic algae and thus clear the water. It was my understanding that it also was toxic to some bacteria. By reducing the algae it resulted in lowering the oxygen level in the water so if I had fish which I had from time to time, I had to be careful on the dosage.
    I also used a solution of copper sulphate to treat the black growth that was growing on my roof shingles.
    Back then my brother had a photo lab. Not one of those compact ones you see at Wal-Mart but one that took hundreds of feet of floor space and used gallons of hot water. He was having bacteria growth in the unit and was affecting the photo quality by appearing as spots on the finished product. By treating the incoming water with just a few crystals of copper sulphate the problem was solved. What reminded me of this was an entry in an above post that copper plumbing had some biocidal characteristics.
  13. Hydronics

    Hydronics Feeling the Heat

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    I thought I might get that response. :) I wasn't suggesting that people operate that way regularly, just a safeguard if you've had bacterial corrosion.
    I understand that it's not ideal to operate this way but unless you've severely overloaded the firebox you should be down to coal at this point in the burn and have burned off most of the gases that would produce creosote which could potentially coat the exchangers. If waiting until 170 or less to fire is the solution, even better.
  14. Der Fuirmeister

    Der Fuirmeister Member

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    Had a very similar experience with my Garn (put into operation 12/09) that I discovered in October of 2010 while preparing to run for the year. Mike helped a lot. Did a clean up and treatment similar to yours (although probably not as good). Mike had me run through the same procedure. I decided to top off the water at the end of this season to eliminate any air and provide all steel in contact with treated water. Will be testing again at that time.

    As for the treatment provided by Garn, it is only a pretreatment, not final treatment, and certainly not add and forget. No where does it say this in the Garn manual. I added and forgot about it. So far this season my water is clear, but after reading this I'm going to take another look and do a mid winter test.

    I spent days on clean up and another $150 on treatment chemicals. One last bit of advice....the tank is confined space. Ventilate with a power (fan) type ventilator and use a O2 meter while inside. People die every year going into what they think is a safe area because they've been in there before.

    edit.... I have a white pex tubing sight glass on mine at the tap port and monitor the water. Helps alert me to potential problems. Low water will cause boiling to occur on the tubes even when below 200 on the gauge. I used to see steam out of my overflow tube. Not this year. I make my last fire around 150-160. Another advantage of running lower temps is higher efficiency.

    I completely agree about Mike and company.....very helpful.
  15. heaterman

    heaterman Minister of Fire

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    Maybe I can clarify the over firing issue.

    Over firing in the case of an open system, any open system, means boiling. As in 212 or whatever your boiling point is relative to your elevation. Como for example would probably boil at around 195* where he is located.

    Boiling does something that water only a few degrees less does not do, and that is that it actually changes the water chemistry. This is especially true if you have some bacterial action taking place in the tank. Nearly all normally encountered bacteria is killed by water temps of only 160* or even less, and the residue of those organisms just sits there in the tank doing nothing. Unless of course it's allowed to build up to an egregious depth on the tank bottom where it can form sludge and create what is called "under deposit" corrosion. ...but that's not the issue Rick had.......
    If there is bacterial or bio based residue in the tank and you boil it what happens is that the Carbon Dioxide in the matter is released and that can bring your PH well into acidic levels with in a few days or even less. The CO2 released from the matter breaks down the water chemistry and now all of a sudden you have a tank full of acid instead of nice balanced water.
    The bio junk in Rick's Garn could have come from something that got in the tank while standing, maybe from the hose he used to fill it with, maybe it was airborne.....who knows? The point is that it was in there and when his unit boiled the water chemistry went down the crapper.

    So what's a guy supposed to do?

    1. Don't boil your Garn, OWB, storage or whatever you have. :)obviously.......
    2. If you do boil it, take a look inside if possible and see what things look like. At the VERY least, take a water sample and get it to a lab within a few days of the event. Tell them what happened and what things look like. Any information you can supply will give them clues to get their research on the right path. Otherwise they are looking for a needle in a haystack.
    3. Do whatever they recommend.
    4. About a week or so before seasonal shut down, take a good sample and send it in. Follow recommendations the lab and/or your manufacturer makes for seasonal shut down.
    5. Take another sample about mid heating season and send that in to monitor what is going on with your chemistry as the year progresses.

    6. Forgot one......fill your Garn, your tank, OWB or whatever to the top or until it overflows during the off season.


    Lot's of us have five figure amounts of equipment, time and materials invested in these systems. A hundred bucks a year is a small price to pay for ensuring long and happy life from your boiler. There are wood burners of all types that I have seen go from functioning to perforated in a very short time. Most folks never bother to find out exactly why but I'd lay money on the fact that their water became acidic for one reason or another. Biological contaminants are only one reason out of dozens that this can happen.
  16. bigburner

    bigburner Feeling the Heat

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    Lot’s of us have five figure amounts of equipment, time and materials invested in these systems. --------------------------------------- and counting!! Another day another HX,valve or something.
  17. Der Fuirmeister

    Der Fuirmeister Member

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    We used city water. Mike tested our tap water and found bacteria. Didn't ask what flavor.....

    I've been told not to use distilled or RO water. Deionized was recommended. No local source and you still need to test and treat regularly no matter what water you use.

    Like Rick I was really upset. The only real answer I've heard is test / treat / monitor.....test / treat / monitor.....test / treat / monitor.
  18. Como

    Como Minister of Fire

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    Sanitation temperature for things like a commercial dishwashers is 180F.

    If I go down to Home Depot I am not going to find anything to treat a hydronic system, but if you went into an English equivalent you would as Radiators are the normal way of heating a house.

    I think most people know that they need to treat the water, my guess is that most do not, or do so infrequently, when things go wrong.

    http://www.fernox.com/files/Fernox/Content/PDF/English/protector_mb1.pdf

    Mentions bacterial issues.
  19. bigburner

    bigburner Feeling the Heat

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    Deionized was recommended. ------------- better check that, it may not be hard on steel but it will attack copper in a big way from what I can remember.
  20. Der Fuirmeister

    Der Fuirmeister Member

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    They do.....http://www.garn.com/
  21. Der Fuirmeister

    Der Fuirmeister Member

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    "...deionized was recommended...".....I should have added....by someone here on this site . For what it's worth, we have zero copper in either of our systems.
  22. Fred61

    Fred61 Minister of Fire

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    It was my understanding that both DI and RO water try to take back whatever was removed from them by attacking whatever is confining them, causing more corrosion.
    Also I wanted to point out that the bacteria living in the hot springs in Yellowstone thrive in both boiling and high acid environment with some being as acidic as battery acid.
  23. steam man

    steam man Minister of Fire

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    I am not sure why distilled water would not be recommended since that's what is put in high pressure boilers and ultra pure water in nuclear reactors to prevent scaling etc. In my field we occasionaly acid clean boilers and then coat or more correctly, "passivate" the carbon steel to prevent corrosion from O2 attack. The higher the temp the more critical it is. I am not sure how you would accomplish that on a low temperature system though I am still looking. The inside of the Garn looked ugly to me. Here's a couple links to the passivation process to better understand it: http://www.vecom.nl/english/documentation/tb/TB-2005-17-eng.pdf and http://www.finishing.com/118/22.shtml.

    Mike
  24. bpirger

    bpirger Minister of Fire

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    Indeed, the Garn site is there, but the forum is gone. Sorry for the miswrite.

    And I will also point out that in the manuals, Garn does go on about bacteria and corrosion. I don't think they have missed the emphasis about treatment, corrosion, and especially from bacteria. No concerns there from a liability stand point whatsoever, in my humble opinion.

    No mention though of a 190 limit.

    Yes, if they rate stored BTU's from 200-120, then I'd have to say that is "assurance" than firing to 200 is OK......

    Not so easy to look inside the beast....that will have to wait. The 8" of fresh snowfall last night conaumed my morning free time....

    The house is warm, the mess is ALL outside, and the oil boiler (and inside woodstove) have been OFF since Nov. Gotta love it!

    Is there any reason why not to add a biocide say annually just as a preventive measure?
  25. Clarkbug

    Clarkbug Minister of Fire

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    I have been reading this thread with interest, since Im hoping to make the jump to the wood-fired boiler-ness in the next few months. Im still a long way from that conceptually and financially, but I lurk to learn instead.

    I wanted to add that deionized water would not be a good idea to fill your system with. Having worked on several lab buildings in the commercial plumbing field, metal piping is not used for any of the connections. While a good portion of this is to eliminate the seams that would be created at fittings etc. that create sites for bacteria growth, the other is what Fred61 mentioned. When you remove the ions from the water, it will readily try to take back whatever is available from the system is in. Plus I can imagine it would be incredibly expensive to fill a residential size with DI water. And by the time you get it to your house, unless the truck that brings it has been cleaned/sterilized, it probably wont be DI by the time it gets there....

    Also, wouldnt these corrosion issues really apply to any of the open systems, such as any of the OWB that exist? Its not specific to a Garn boiler, other than where they have a coating on the interior parts, from what I have gathered. Also, once the inside of the top of the boiler "rusts" (used for lack of a better term) wouldnt that effectively passivate the metal that isnt submerged in water?

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