Outfoxing Old "Rusty"?

A Coal stoker furnace or stove controls most operations including automatically feeding the coal. They are quite similar to any conventional oil and gas units and easily operated for extended periods of time. They commonly use rice coal but may use larger sizes like buckwheat. They can be used as primary heat, supplementary heat or have a dual set up with your existing oil/gas furnace.
stockingfull
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Stove/Furnace Make: Yellow Flame
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Post Mon. Oct. 12, 2009 12:46 am

OK, I'm lazy, cheap and a refugee engineer.

All that being the case, I've been reading about the fancy oils that everybody buys for spring spa treatments for their stoves/stokers. And the notes by those who burn year-round, not surprisingly, that there's no opportunity for corrosion if the fire never goes out.

So I decided to do an experiment last spring. When I turned my furnace off, I waited about an hour for it to cool a bit, then popped off the flue and capped the outlet. Didn't clean it, didn't wrap the intake side, didn't empty the hopper, didn't even take the last ash bin out. My thesis was that if I didn't give it a chance to "breathe" the humid summer air, maybe I could reduce corrosion.

And we surely had a humid summer.

Tonight, like for so many others here, it was time to fire it up. So off came the flue cap and out came the shop-vac. The usual ash, but much less than the usual amount of rust. I'm counting it as a victory.

Hope the Phils have the same luck in this cold!


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stovepipemike
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Post Mon. Oct. 12, 2009 7:22 am

Stockingful,You must give your conclusion as to why it worked out for you.Do you think that a layer of fuzzy powder of coal ash acted as a blanket to keep migrating humidity from good access to the metal? is it possible that the volume of ash absorbed some stray humidity? You just might be on to something here.Any pictures?

stockingfull
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Post Mon. Oct. 12, 2009 9:54 am

Naw, much more simple: I just locked in the super-dry furnace air right after shutoff and didn't "open the can" till yesterday.

No moisture, no corrosion. Simple.

CoaLen
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Hot Air Coal Stoker Furnace: Keystoker Koker
Coal Size/Type: rice
Location: Northeast Ohio

Post Mon. Oct. 12, 2009 5:34 pm

Stockingfull,
For what it's worth, I'm in your camp on this issue. I can't see how swabbing the inside of my Koker with water and baking soda will be good. I would do it if I could hit it with a pressure washer and soda, cleaning it to the bare metal. But doing the swabbing thing probably causes more problems than it'll solve. I simply scraped and wire brushed and vacuumed as best I could and then put a couple of desiccant packs inside and sealed it up for the summer.
A while back Freddy questioned the wisdom of the baking soda wash and after thinking about it, I decided he's probably correct.
Here's his post:
Freddy wrote:I guess I'm a bit lost on the baking soda thing. After I vacuumed my boiler out there was just a whisper of ash left on the metal. Even if that were pure acid it seems that it couldn't make much rust. I'm thinking the people that have severe rust issues have the stove in a damp environment. I'm inclined to think the water mixed with the baking soda does more harm than good. Just my $.03. Maybe dust it with dry baking soda?
I'm about to start up again for the winter and the Koker made it through the summer in good shape. I'm convinced the "dry cleaning" method along with desiccant bags is the way to go for my situation.
-Len
“The trouble with quotes on the Internet is you never know if they are genuine.” —Abraham Lincoln

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009to090
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Stoker Coal Boiler: EFM 520 HighBoy
Hot Air Coal Stoker Stove: DVC-500 x 2
Coal Size/Type: Anthracite Rice
Location: Warrenton, NC

Post Mon. Oct. 12, 2009 6:02 pm

Wow! Surprising ! :shock: You may have something there. I didn't have any rust until AFTER I swabbed out the inside of my stoker with a Baking soda / water mix. The acidic ash acted IMMEDIATELY with the water, I guess BEFORE the baking soda could do its Neutralizing thing? It bubbled up, fizzed, and immediately turned red-rust color.
If it ain't broke, don't fix it!

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VigIIPeaBurner
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Hot Air Coal Stoker Furnace: Keystoker Koker
Hand Fed Coal Stove: Vermont Casting Vigilant II 2310
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Location: Pequest River Valley, Warren Co NJ

Post Mon. Oct. 12, 2009 6:03 pm

Stovepipemike and Stockingfull pose some good questions about this system. Thinking about the layer of 'protective' ash from the surface perspective, I asked myself what forms rust? It's FeO2, iron oxide. The oiling procedure is done to provide a physical barrier against O2 contacting the bare metal. Washing with baking soda, Sodium Bicarbonate, does nothing to prevent rusting. It's done to neutralize any remaining H2SO4, sulfuric acid, that might form from as sulfur oxidizes in the presence of water. The sulfuric acid is corrosive to the metal IF it contacts the metal surface.

Now, back to that layer of 'protective' ash, if there's sufficient water and oxygen that contacts the ash, there can be sulfuric acid formed. If the acid is formed, it reacts with the water and the oxygen in the layer of ash. It would react from the outside toward the inside of the ash layer. If the water and oxygen are used up in that layer of 'protective' ash, oxidation/rusting of the metal surface could be minimized as less O2 reaches the 'unprotected' ferrous surface.

Maybe that's what is happening. Thoughts?
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traderfjp
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Post Mon. Oct. 12, 2009 6:37 pm

I've tried the vacuum thing and left it alone to see the sides of my stove start to flake. For me it's best to wash out the inside with water and baking soda and then coat with LP3. The ash will absorb the humidity in the air and start rusting the metal. I guess if you closed everything and used damprid or a lightbulb then cleaning it with a wash isn't necessary. IMHO
Disclaimer: I'm not an expert in any coal or plumbing related field. I only post my own experiences, research and common sense. If you choose to use any of the information in this post or any other post you do so at your own risk.

stockingfull
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Post Mon. Oct. 12, 2009 7:58 pm

We need a chemist to answer whether pure oxygen can combine with the iron molecules, in the absence of moisture, to form FeO2, or whether moisture is required.

If I had to bet, I'd bet on the latter, since we obviously don't have corrosion problems while we're pumping mega-volumes of oxygen-laden air through there during heating season. (Maybe H2O + Fe + the S in coal = FeO2 and H2SO4, or some such.)

I don't think the ash layer has any effect on it, one way or the other, except as a distraction. My experiment was focused on "canning" the super-dry air inside the firebox as soon as I shut the thing off, in order to hold and "mimic" the atmosphere in there during the burn season.

Next spring I plan to wrap the intake side and go for the gold!


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Poconoeagle
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Post Mon. Oct. 12, 2009 8:10 pm

get it to seal so tight that a good automotive a/c vaccuum pump could suck all the air and moisture out down to at least -29.99 in/mg or better yet then fill it with nitrogen.. or maybe huff on the nitrious oxide from the race car and not care about the rust..... this I believe is actually what Whistle nut does but keeps a closet secret... :shock: ;) :lol: 8-)
"Do it Right the First Time" dont leave it for the next guy, as YOU may be the Next guy!!

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VigIIPeaBurner
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Location: Pequest River Valley, Warren Co NJ

Post Mon. Oct. 12, 2009 8:42 pm

Poconoeagle wrote:get it to seal so tight that a good automotive a/c vaccuum pump could suck all the air and moisture out down to at least -29.99 in/mg or better yet then fill it with nitrogen.. or maybe huff on the nitrious oxide from the race car and not care about the rust..... this I believe is actually what Whistle nut does but keeps a closet secret... :shock: ;) :lol: 8-)
The next question is, will he share? :)
stockingfull wrote:We need a chemist to answer whether pure oxygen can combine with the iron molecules, in the absence of moisture, to form FeO2, or whether moisture is required.

If I had to bet, I'd bet on the latter, since we obviously don't have corrosion problems while we're pumping mega-volumes of oxygen-laden air through there during heating season. (Maybe H2O + Fe + the S in coal = FeO2 and H2SO4, or some such.)
Right, either process needs water. Wrap it up or coat it in cosmolene, lps - an oil wrap - and expend the small amount of water trapped and nothing more reacts. What's that item people place in their gun lockers, a golden rod? It heats the space up to keep the water molecules moveing so as not to stay in contact on the gun's surface. That's another way to limit 'contact' with corrosion causing moisture.

... am I near a Holiday in Express?
3 Videos: Chavez can shov(el) it . . . & he's @ it full time now!

CapeCoaler
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Post Mon. Oct. 12, 2009 9:53 pm

Depends what exit you are at! :lol:

Light bulb or goldenrod keep the container/stove warm/er and keep the relative humidity down.
Wrap the stove in a bubble and pump in the Nitrogen...
Eliminate the Oxygen...
Stop the rust!
Or you could dunk/submerge in a tank of Oil.
I am not an engineer, train or otherwise!
I stay at a Holiday Inn at least once a year!
Most of all I do have common sense and a practical application of logic.
Oh, add humor, on the dry side, along with a wee bit 'o sarcasm.

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europachris
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Post Tue. Oct. 13, 2009 8:43 am

I've used DampRid for two years in my Keystoker after vacuuming out the entire stove thoroughly shortly after shutting down. I remove the exhaust from the DV and seal up the hopper opening at the bottom and the intake and exhaust ports. Even with the stove "sealed", I'm amazed at how much water collects in the DampRid bucket over the summer. Average basement conditions in the summer are 65F and 60%RH, maybe 70% if it's been really rainy. I have a dehumidifier as well as central A/C that has a return vent in the basement (finished).

But, rust formation inside the stove is nil, so I'm quite happy with the results. Actually last year I started the stove for a few weeks and then we had a week or two of Indian summer, so I shut it down. With it open to the outside through the DV and a fresh coating of combustion residue, it rusted quickly inside in many areas.

Chris
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I love the smell of Illinois bituminous in the morning.
Have you hooked a clinker today?

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Carbon12
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Other Heating: Heat Pump/Forced Hot Air Oil Furnace
Location: Harrisburg, PA

Post Sat. Nov. 23, 2013 12:27 pm

I just read an article that instructed boiler operators, upon prolonged shut down, to place a large container of unslaked lime inside the ash pit and close the boiler up tight. The unslaked lime absorbs moisture inside the burn chamber and prevents rusting. Anyone know anything about this???
No matter where you go,......there you are.

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carlherrnstein
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Post Sat. Nov. 23, 2013 1:08 pm

Unslaked lime is another name for calicum oxide. It's nasty stuff it can cause chemical burns, if you mix it with water it will make the water boil and it is almost impossible to find. Just put a light bulb in there and leave it alone.
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Carbon12
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Post Sat. Nov. 23, 2013 1:11 pm

Nasty stuff for sure! Sounds like fun though,....if you're sporting a Hazmat suit :shock:
No matter where you go,......there you are.


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