Corn stove waste heat reclaimer

[Jaw818]

Last winter I heated my house with propane (first heating season i paid for), and it was painful. The propane shortage shot prices over $5 per gallon. so this summer I found a steal of a deal on a St. Croix Auburn for $100. My neighbor is a farmer and I'm getting corn for $3.40 a bushel, got a 170 bushel gravity box for $300, so I'm feeling pretty good about the impending weather.

But in my never ending itch to tinker with things has got me thinking:

The stove requires a 3" exhaust, but the store only had 4 inch, so I have 4 ft of 4" pipe sticking out of my wall, and the exhaust is incredibly hot coming out. Seems like a lot of wasted energy. Is there a reason exhaust heat exchangers aren't around for these? I was thinking of winding some copper tubing inside the pipe and running some water through it, or rigging up some sort of air-to-air exchanger.

Not sure what I would heat with it yet, possibly a dog house, maybe my hot water, or distribute it to the bedroom in the back of the house? I guess I will worry about what to do with the heat once I decide its a feasible endeavor.

So does anyone have experience with this, reason it would or wouldn't work? Best practices?

Thanks in advance

 

[Bioburner]

Giving the Farmer a nice premium.
Once the weather gets colder the exchanger will suck more of the heat out of the exhaust. You get to low and condensate will collect and burning corn will create a lot of acid and put your venting to the test. If you put copper in that stream and you will end up with nothing but copper sulfate in very short order. Make sure the stove is very clean to get the most heat out of your fuel. Ash and carbon is a very good insulator.
I was trying to get a Auburn if for nothing but to know how they worked.
Welcome to the site.

 

[bill3rail]

Welcome to the club, you'll love the savings, and congratulations on the fantastic deal. I would have bought the stove even if I did not need it.
There have been a few discussions here about heat exchangers on exhaust pipes.
We ran our pipe straight out because we didn't want to see it above the stove, so not much heat for us to recapture.

Bill

 

[Jaw818]

A nice premium? Considering the previous quote I got was $4.00 from another farmer, I thought 3.40 was pretty good. What are prices in your area and where do you get it from? Perhaps I need to do more shopping.

I have noticed from other people who burn corn that their stainless double walled pipes do seem to rot pretty bad after a few years of use. I'd there a better alternative for exhaust than stainless?

The auburn is pretty simple it seems. I've heard nothing but good reviews of them. The current set up is only for corn, but it sound like a conversion kit to burn either corn or pellets isn't to much, and I may look into that when corn prices go back up. Also curious about pellet vs. Corn. Is seems people are very passionate one way or the other, and I've had a hard time deciding what is better. I've heard corn is hotter, pellets are cleaner, wondering what the cost difference works out to be. But this is probably better suited to a new thread I suppose.

 

[Jaw818]

Welcome to the club, you'll love the savings, and congratulations on the fantastic deal. I would have bought the stove even if I did not need it.
There have been a few discussions here about heat exchangers on exhaust pipes.
We ran our pipe straight out because we didn't want to see it above the stove, so not much heat for us to recapture.

Bill

Thanks Bill. I did the same with my exhaust. The guy I got it from had 2, and apparently scrapped one earlier this summer because no one came to buy it and he wanted it out of his garage. It's to bad because I would have bought both. However I'm still very happy with the deal I got. The exhaust pipe cost me more than the stove, and it was really a no brainer when I can recoup the investment in one season. Plus it will be nice to have a homey looking "fireplace" in the house to add to the feeling of warmth.

 

[Arti]

A nice premium? Considering the previous quote I got was $4.00 from another farmer, I thought 3.40 was pretty good. What are prices in your area and where do you get it from? Perhaps I need to do more shopping.

I have noticed from other people who burn corn that their stainless double walled pipes do seem to rot pretty bad after a few years of use. I'd there a better alternative for exhaust than stainless?

The auburn is pretty simple it seems. I've heard nothing but good reviews of them. The current set up is only for corn, but it sound like a conversion kit to burn either corn or pellets isn't to much, and I may look into that when corn prices go back up. Also curious about pellet vs. Corn. Is seems people are very passionate one way or the other, and I've had a hard time deciding what is better. I've heard corn is hotter, pellets are cleaner, wondering what the cost difference works out to be. But this is probably better suited to a new thread I suppose.

I burn corn when it gets colder out usually a mix of corn and pellets, the corn needs to be fairly clean and as dry as you can get it. 10% moisture is a good number to aim for.
Last years corn is about $3 a bushel locally however most farmers don't really like to mess around with a couple of ton of corn and deserve a few cents for their time. I suspect it costs them in the area of $4 a bushel to produce it..

If you do the math $5 bushel corn is about the same as the current price of pellets so anything under that is a savings. As far as heat output of corn it seems like it is the same as pellets, a few more clinkers and it smells good. I light my stoves with softwood pellets as corn is difficult to get hot enough to burn when everything is cold. A handful of oyster shells in a hopper of corn keeps things cleaner and helps with the corrosion problem

 

[Bioburner]

Go to Linder farm report and you can plug in your zip to get local elevator prices. I bought on July 8 for $130 a ton and prices continued to go down and I think I last checked could get corn from the elevator for about $100 a ton. Less than $3 a bu.

 

[Jaw818]

Well, just called the local feed mill this morning. Their elevator price for shelled corn is $152 per ton, which is 4.25 a bushel. Maybe I just live in a more expensive area here in east central mn? I'm surrounded by corn fields in every direction, so I can't imagine why, but $3.40 will still save me a lot of money so I guess I'm not to heart broke.

Arti, when you talk about oyster shells, are you just referring to crushed oyster Shells? What does that do to help? I'll have to see if one of the stores in town carries them. Thanks for the tip.

Chickenman, I'll contact Bob and check into that. Is it a double walled flue that allows air to circulate I between the walls or how does it work? Any chance for the sake of the thread you can post some pictures and a description? Thank you.

 

[Bioburner]

I just checked local price at elevator and was 2.91/bu plus 20 cents for sale

 

[Jaw818]

I just checked local price at elevator and was 2.91/bu plus 20 cents for sale

Looks like it's just more expensive where I am for some reason, called every mill in the area this morning, 4.09 a bushel was the cheapest, 4.49 was the high price. It's 7.80 to buy a 50lb bag from fleet farm or Walmart. Almost seems like it would be worth it to borrow dad's dump truck and drive out to your area to get it. Wonder why it's so much more here. Proximity to the cities maybe?

 

[Bioburner]

Could be as its closer to shipping ports etc where we have to rail everything to Cargil. I have to go to pellet broker in Bethel to get decent price on premium blend pellets to feed the Elena.