OWB - Open Systems Corrosion Problems!

[myleakywooddoctor]

I am the not so proud owner of my second 2000 lbs stainless steel exterior wood furnace sold to me by Wood Doctor.

My original furnace developed perforations in it's belly causing it to loose all it's water in only it's second heating season. I managed to make it to spring by holding vigilance over ten or so pine plugs hammered into the holes to stop the leaks! :red:

I received a replacement stainless steel boiler that has now just barely made it threw it's third heating season this time developing perforations primarily along the belly weld lines! :sick:

So what can be done to reduce the corrosion problems in open systems? :question:

Well one thing I have done is introduce an anode into the piping on the back of my Wood Doctor hoping for the best!

A picture is worth a thousand words . . . see below!

A standard DHW anode is inside the black iron with a ground wire strapped on to ensure it's grounded (above is my spare anode).

Well, it should have help tremendously! My boiler is supposed to be high quality heavy gauge Stainless Steel after all! :-/

Perhaps on another product, it would have made a great difference! :zip:

Leaky :down:

 

[Piker]

stainless steel is prone to what is called stress corrosion cracking. It's actually not the best thing to build a firebox out of. It has about twice the thermal expansion rate of A-36 boiler plate. I won't deal with any SS wood boiler products for this reason alone. SS doesn't weld very easy once it cracks either.

A properly cared for boiler manufactured from carbon steel will give decades of trouble free service. Sorry if this post isn't much help for your current situation.

cheers

 

[slowzuki]

I'm not sure what type of treatment would help but there should be some boiler treatments that would slow the corrosion rate.

 

[leaddog]

There are a lot of different grades of stainless and all have different properties. Some will even atract a magnet. They make the boilers out of a thinner guage also because of the cost. My neighbor has several that he picked up to scrap that are all stainless and they are full of holes. Looked like it was a cheap grade and wasn't uniform steel. Probably from a small mill in china.
leaddog

 

[jebatty]

All those smiley faces ... really? An occasional one might do the trick, if really needed.

 

[pybyr]

I like stainless for a lot of applications- but the assumption that it is corrosion free is a total mis-understanding.

Under some chemical and temperature variables, some alloys of stainless can develop deep voids that ruin its structure and make it swiss cheese - especially, if, as someone mentioned, it's of dubious homogeneity of the alloyed elements.

As an illustration, I have a huge (3 gallon) upscale stainless cookpot (that I got for cheap on close-out) that I use to boil down applesauce from my old farm trees- one time some applesauce burned to the bottom, and then, a pocket of some impurity burrowed itself a hole right through the bottom.

Luckily the carbon of the burning applesauce then stopped the little hole up- but I was unimpressed, even after having bought the thing for $0.15 on the dollar.

 

[myleakywooddoctor]

There are a lot of different grades of stainless and all have different properties. Some will even atract a magnet. They make the boilers out of a thinner guage also because of the cost. My neighbor has several that he picked up to scrap that are all stainless and they are full of holes. Looked like it was a cheap grade and wasn't uniform steel. Probably from a small mill in china.
leaddog

Yes,

This is what I think must be going on - cheap 409 made somewhere where quality control is a joke and aloud into our country for the sake of saving a buck on materials!

On my system I also see evidence that seems to indicate to me that the stainless my have been improperly welded causing it to loose it's anti-corrosive properties along weld lines. This is where mine is perforated - along the weld lines (see picture)!

Leaky :-/

 

[slowzuki]

Very common failure in SS. Even if the right filler rod is used often no or wrong post weld heat treat is done and the grain at the weld is just ripe for corrosion. Happens in SS sprinkler systems too.

 

[Ugly]

There are a lot of Empyre's ( I know 12 people who have them personally and others second hand) around these parts, all of them getting on in age (like the rest of us). No problems to report among the farmers using them. I'm given to understand they are made from 304L stainless. (AKA type 1.4307 ).

This topic and other leak topics I've read on the boards all leave me scratching my head. What is the common failure point of the open boiler? materials? construction? It's something I'd personally like to avoid yet I see these open boilers (some getting very on in years) with little or no trouble.

Has anyone had a leak that wasn't on the seam with a boiler specifically constructed from 304L? Seam leaks should be avoidable with proper construction but it if it flat out rots through then I don't want that happening either...

304L was my original material choice as it seems a good product for long lasting out door use on the surface, but now I'm scratching my head and wondering if A-36 boiler plate is the best choice after all. Boiler plate is sure cheaper and easy to mig

 

[Eric Johnson]

My dad has a 12-year-old Heatmor that failed in the first year. Carbon steel firebox. They replaced the original box with ss and it's still holding water. He did just spring a leak in the door (which contains fluid). He's not sure how much longer it will last and I think he doesn't want to risk having it fail mid-winter.

 

[Hydronics]

One thing to consider is that it may not be corrosion. It may be failing due to thermal stresses especially if the failures are adjacent to welds. Welding can induce stress in the metal as the weld cools it does so unevenly this is why critical welds are often preheated or heated after welding to relieve the stress. Welding can also concentrate the carbon in the steel at the weld making it brittle there.

 

[pybyr]

There are a lot of different grades of stainless and all have different properties. Some will even atract a magnet. They make the boilers out of a thinner guage also because of the cost. My neighbor has several that he picked up to scrap that are all stainless and they are full of holes. Looked like it was a cheap grade and wasn't uniform steel. Probably from a small mill in china.
leaddog

Yes,

This is what I think must be going on - cheap 409 made somewhere where quality control is a joke and aloud into our country for the sake of saving a buck on materials!

On my system I also see evidence that seems to indicate to me that the stainless my have been improperly welded causing it to loose it's anti-corrosive properties along weld lines. This is where mine is perforated - along the weld lines (see picture)!

Leaky :-/

409 is not automatically awful- each of the various alloys has certain advantages and disadvantages for various applications.

But as others have said, steel, of any alloy, made with poor quality control, or assembled with poor techniques (welding stainless well is much more challenging that welding many other things) is an invite to problems.

 

[myleakywooddoctor]

I'm going to post my boiler treatment recomendations from Wood Doctor as it appears they have completely changed their tune on this since my first two SS boilers developed leaks!

I'm interested to see what other OWB Dealer's are telling their clients to do as well!

Ok, here I'll post what I was originally told to do by Wood Doctor!

In my next response, you can see what they say to do after I have already had two boiler corrode through!

Leaky :-S

 

[myleakywooddoctor]

This is what they say now!

Leaky :-/

 

[webbie]

This topic and other leak topics I've read on the boards all leave me scratching my head. What is the common failure point of the open boiler? materials? construction? It's something I'd personally like to avoid yet I see these open boilers (some getting very on in years) with little or no trouble.

The common failure point is lack of engineering. The idea that anyone can just draw up or weld up something which holds water....and that it will continue to do so many years afterward.

They say history repeats itself - boiler standards started hundreds of years ago with the steam engine and railroads. The science has continued with ASME, special alloys and ISO standards.

But Outdoor Boilers (many, if not most) throw all these standards under the bus because they are non-pressurized. And, the cost of entry to the manufacturing of these is so low that it begs for less experience operators and lack of engineering.

Personally, I would look harder at larger and more experienced manufacturers like Central, etc...not to favor one over the other, but because they actually have many engineers on staff, a long history, etc.

I am not an engineer by any means, but there is probably some truth in Centrals page which states good carbon steel is superior.
(broken link removed)

Stainless is great for many things, but pressure vessels (or even non-pressure vessels) is not the #1 use......

 

[myleakywooddoctor]

Here's some more interesting stuff!

Eyes Wide Open! :gulp:

Here is an very interesting blurb I just received from a friend!!

Can't say I know for sure if it is all correct, but it sure sounds feasible to me!!

How Wood Doctor can just sell customers an OWB and then just leave them in the dark about all this stuff, I do not know???

Well hey, they are the ones warrantying the durability of their products against corrosion among other things, so they're actually the ones on the hook to fix these leaking beast, or so you would think!!

My friend says the following in regard to my . . .

"Corroded Leaking FULLY WARRANTIED Heavy Gauge Stainless Steel WOOD DOCTOR Furnace"

*****************
I would venture to suggest, that they may be using 406 stainless as it welds up good with normal steel panels. However, it also has the characteristic of creating galvanic cells within itself if it lays submerged in still brackish water (freshwater with higher then normal chloride levels).

Are you leaving your system full in the summer when not in use and have you tested water for chloride levels (salt). It could be that you are using system in the summer too, but you are not getting enough demand to keep water circulating enough. Whatever the case, it could be that there are pockets of still brackish water forming galvanic cells next to the stainless!

Unless you are regularly blowing down (draining boiler bottom liquid/sludge out under pressure) and topping up with new water you will over time have chloride build up to dangerous levels (levels high enough that the boiler water becomes an electrolyte and allows galvanic cells to form). Then away goes the iron in your stainless steel alloy and oops there is a hole. This will occur mostly near the bottom of your boiler where salt concentrations will be highest!

Monitoring PH levels is good, but PH only helps reduce corrosion by keeping water slightly alkaline. Unfortunately, even alkaline water becomes an electrolyte if chloride (salt) PPM get high enough.

Desired level of chlorides should be around 15-25 PPM, but practically you would probably have difficulty keeping it between 50-75 PPM.

You need to test water with silver nitrate chloride test kit to get PPM. You will likely find that you will need to start draining water regularly to keep chloride levels down. You are shooting yourself in the foot by running the same old soup in system forever, or in this case until it cuts it's own drain holes and runs out on the ground.

In these open systems, boiler water will only continue to build in chloride content as pure water is boiled off (concentrating the soup) and then new water containing even minute levels of salts is added! That is why boiler water neutrality is controlled by controlling it's dissolved solids (salts etc.).

You don't have to re-invent the wheel here, just trust the accepted methodology. The idea is to reduce the capability of your water to conduct current, thereby reducing corrosion caused by galvanic cells (dissimilar metal molecules next to each other in your stainless steel alloy mix). Again this is relative, but basically dissimilar metals that are fused together in an alloy create there own electric circuit (or electron flow), this is how thermal couples work. Anyway, in a mixture (an alloy) an electrolyte is also needed to allow this electron flow to occur (like a battery). Reduce the strength of the electrolyte and you will reduce electron flow and thereby reduce corrosion!
*****************

Please, someone with some additional knowledge about this subject offer us some more insight!

Are there OWB dealers out there telling there customers they need to flush their furnaces on some kind of regular basis, or what?

Did you all notice this particular sentence . . . "You don't have to re-invent the wheel here, just trust the accepted methodology" >:-(

I'm putting a pic here showing those holes in my Wood Doctor heavy gauge stainless steel furnace . . .

Leaky :sick:

 

[freak]

I have a Boiler Plate model and it is 6 years old and has started to leak. My furnace was filled with antifreeze to help prevent corrosion, but that was a waist of time. I am being told that " because I had installed a 8 foot section of chimney, condensation in the smoke pipe and ran down inside the firebox and this contributed to the welds failing(Rusting Out)." They are denying warranty. The warranty on the furnace is only good for 5 years. I saw the classic boiler furnaces a week after I had purchased my Wood Doctor and I thought it was a much better furnace, and now I am sure that I made a mistake. If they offered to give me a new furnace to replace this one I would sell it for as much as I could get for it and buy a Classic Boiler. I know there are allot of dead Wood Doctors in this area. The furnace worked well up until now, but I was waiting for the past two years for something to go wrong with it after hearing other peoples stories.

 

[myleakywooddoctor]

What a farce . . . yours rusted from the outside-in (inside-out to me would be from the water jacket, out!) and they are denying warranty. :red:

Does Wood Doctor say anywhere in the literature they provided to you that there is a limit on the length of pipe you can install and that this may happen if you install too long a piece and they will there-by void your warranty?

Did they convince you to ship your entire boiler to their factory for examination at your expense and then pull this excuse to void your warranty out of their hat?

So, "Now We Know!!", Wood Doctor's boiler plate lasts about 6 heating seasons before corroding through and leaking all over the ground and Heavy Duty Stainless Steel can corrode through in less than 3 heating seasons!!

Isn't that Wood Doctor product just the cat's meow!

So to add to the confusion that Wood Doctor seems to wallow in . . . is your boiler "Heavy Duty Full Boiler Plate" or did they manage to slip you something they might now describe as "Light Duty Half Boiler Plate" that you didn't think you had bought from them in the first place?

Wood Doctor is telling me now, that I originally bought a Light Duty Stainless Steel Global Hydronics boiler from them. Funny, how I never heard any of these terms until well after the fact! I know what I bought from them, "A Heavy Duty Stainless Steel Wood Doctor Furnace!"

It's like they're trying to say, "You bought our cheap product and got what you paid for! What did you expect, Dah!" >:-(


Leaky :down:

 

[freak]

I can't find the literature that came with the furnace when I bought it, I will look for it soon. But I have a friend with the same set up and he isn't having any problems (YET). They told me that my furnace only had a 5 year warranty and I'm not sure what the replacement warranty is, I have to talk to them again. It's not like I purchased there cheapest model. I paid almost 10 000 for the furnace, its a big one.
What I am planning to do is to get a welder down and cut the thing wide open and perform the repairs and I will take some pictures of the thing opened up and then I am going to put it in the Auto Trader for sale as scrap metal. Free advertising for them, I will also put it on the net. I was so upset when they screwed me around, I decided that I would have more fun screwing with them and hopefully prevent someone else from making the same mistake that I did. They didn't even come look at it. I called them when I discovered the problem and it took them almost 3 weeks to get back to me and say they were not going to cover it. Its a real candy ass operation that they are running. I am going to take the furnace right apart and inspect the entire furnace and rebuild it they way they should have built it in the first place. And when it blowes up I will buy a one from Central Boiler.

 

[myleakywooddoctor]

Wood Doctor didn't even come look!

No curiosity on their part, ahy! :roll:

They already know what the problem is - don't they!

Post some pictures when you get some - they're worth 1000 words you know! ;-)


Leaky :down:

 

[myleakywooddoctor]

Hey,

I have heard via the grape vine that Wood Doctor maybe soon be sending a certified welder to my home to repair my leaking beastie! 8-/

If this actually happens, the words "On Site" in my warranty will actually mean, "On Site!" .

I hope to be impressed by the work that is done to repair the many leaks and cracks in my Wood Doctor boiler and will be sure to post a number of pictures here to document the work for all to see!

Perhaps next heating season will be a "leak-free" one!

Leaky

 

[runningmike]

Lots of scary talk here about corrosion and water treatment. After my first successful season with a Woodmaster 4400 my fingers are crossed... Now, that said, it's time to flush and treat my system. WM sells their brand name treatment but it's expensive. Any thoughts on suitable, or better (and cheaper!) alternatives?

Mike

Woodmaster 4400
Poulan junk (In the market for a good Stihl)
8lb sledge, 4 blaster wedges

 

[jebatty]

I'm wondering why you want to flush (and treat) your system? If it's been in operation for a season, and properly treated to begin with, all that should be required is periodic monitoring (especially an open system) to make sure that pH and O2 control chemicals are correct. Both may change with addition of water. If a closed system, perhaps an occasional check, but unless significant water is added, the system should be good for a very long time. I suspect that most people with oil or NG closed system boilers have never checked the condition of their boiler water, and these boilers last for a very long time. The water side of a wood boiler should be no different (unless an open system).

Flushing and refilling the system introduces large quantities of O2, and all new chemicals again have to be added. Why do this?

BTW, I operated an OWB for 10 years doing no more than adding sodium suflite periodically to control O2. The prior owner also operated the boiler for about the same time period. I then sold the boiler in apparent good operating condition. I now have operated the Tarm for two full seasons, treated initially for pH and O2, and the water has been and remains clear, and pH is where it is supposed to be.

I think more important than flushing and retreating the innards is removing creosote and sealing the boiler from moisture in the firebox and all areas where creosote and the smoke stream comes in contact with boiler steel while the boiler is shut down. Any creosote in contact with steel, when also moisture is available, creates acid which is good for corrosion on the steel.

 

[runningmike]

"I’m wondering why you want to flush (and treat) your system? If it’s been in operation for a season, and properly treated to begin with, all that should be required is periodic monitoring (especially an open system) to make sure that pH and O2 control chemicals are correct."

You are probably correct. But, call me naive, I'm simply following the end-of-heating-season guidance as documented in my Woodmaster paperwork. I am assuming that if not followed correctly, certain parts of my warranty will be voided.

Mike

 

[myleakywooddoctor]

"I’m wondering why you want to flush (and treat) your system? If it’s been in operation for a season, and properly treated to begin with, all that should be required is periodic monitoring (especially an open system) to make sure that pH and O2 control chemicals are correct."

You are probably correct. But, call me naive, I'm simply following the end-of-heating-season guidance as documented in my Woodmaster paperwork. I am assuming that if not followed correctly, certain parts of my warranty will be voided.

Mike

Hey,

So there are warranties out there requiring that the system be flushed Yearly!

Perhaps the manufacturers are getting wise to salt build-up! ;-)

Wood Doctor sends a Welder!

See my post under Outdoor Wood Boilers Review . . .

Leaky

PS - I think I have found a test kit that I can now monitor salt concentration with! Also, salt seems to concentrate at the bottom of my boiler and I now have a ball valve to allow me to drain off water from the bottom and add fresh to the top if I detect a build up of salt!

Wish me luck! :roll: