# Question about crack in wood stove



## suitcase_sally (Mar 20, 2006)

I posted a few days ago about a hairline crack in the top of my Franklin stove. Can this be sealed with cement or anything? DH is concerned about carbon monoxide leaking out. The crack is truly a hairline crack - very tiny.


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## blooba (Feb 9, 2010)

I do beleive they have a JB Weld for high temps. Although that won't "fix" it just seals it. The problem is once there is a crack with the expanding and contracting when it heats and cools that the crack will grow.


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## suitcase_sally (Mar 20, 2006)

Rats! That was what I was afraid of.

Any opinions on wood stoves? I need something that I can place close to a wall. My space that needs heating is about 700 sq. ft.


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## Harry Chickpea (Dec 19, 2008)

CO won't leak out. The draft keeps a negative pressure on the interior of the stove, so air gets sucked IN.


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## ldc (Oct 11, 2006)

Also, use a CO2 monitor, then the alarm goes off if there's a mishap! ldc


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## suitcase_sally (Mar 20, 2006)

Thanks, Harry!


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## Wis Bang 2 (Jan 12, 2010)

Drilling the end of the crack may stop it from spreading it is a common thing to do to stop cracks in metal. 

Drilling a few holes along the crack may give the HI Temp J B Weld a place to hold on as well instead of just speading a bead on top of the crack which may not hold/seal...

I believe cast iron can be brazed and can be welded if preheated by a welder who knows his stuff BUT arc welding, improperly done, will warp it.


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## tamsam (May 12, 2006)

If a few tiny leaks are a problem, Lord help us, as we use an old stove that is not air tight. I sealed it best I could with high temp sealer but I can still see the fire in a couple places when the lights are off. If the chimney draws it sucks all the gases out the chimney. We burn a lot of coal and no one has ever said they can smell it in the house. We have been using this old KING-O-HEAT heater for 5 years now with no problems. Wish I could find another one to put in storage just in case this one breaks or something. Sam


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## foxtrapper (Dec 23, 2003)

It can be welded. I know lots of folk think iron can't be welded, but it can, and quite easily.


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## suitcase_sally (Mar 20, 2006)

Hmm....I was a die maker in the auto industry before going into engineering. Whenever we had a die break (the cast iron "shoe", not the trim steels and such) we put what was called a "dutchman" on the casting to hold it together. I don't think that would work in this situation due to the cast iron being as thin as it is.

Iron (as in boiler plate) can be welded, but I don't recall ever welding _cast_ iron.

I, too, have heard that it can be welded, but it takes a bit more expertise than what I have to do so.


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## FarmboyBill (Aug 19, 2005)

Remember, If the stove has been heated enough to crack, then the temper is gone out of the cast, and youll N E V E R be able to weld it. NEXT I dont think throwing crack inna stove will do u any good, the cops will smell it burning LOL


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## HermitJohn (May 10, 2002)

Quality cast iron can be welded. Cheap thin castings spider web. My opinion is that on stove best to braze it. There would be no advantage to welding on such an application. 

Also hairline crack is no threat as to CO leakage.


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## Cabin Fever (May 10, 2002)

IMHO, it isn't worth your while trying to weld a cast iron Franklin stove. If it was a quality air-tight cast iron stove, maybe it would be. My recommendation would be to find yourself a good plate steel stove.


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## highlands (Jul 18, 2004)

Seems to me that it would be a very bad idea to have any derivative of cocaine in your wood stove... (Sorry, couldn't resist a crack about crack in a woodstove... *sign*  )

Seriously though, officially I have to advise you to toss it out and buy a new approved woodstove so that you can increase the Gross Domestic Product and consumer spending. Unofficially I patched our 40 year old wood furnace for decades without any problem. By the time I finally stopped using it it must have been more patch than cast iron - just kidding, the door was still mostly iron. I used a stove cement that setup hard when heated. It was made for that purpose.

I would also suggest having a carbon monoxide detector and adequate air intake for the stove, ideally dedicated to the stove.

Cheers

-Walter
Sugar Mountain Farm
Pastured Pigs, Sheep & Kids
in the mountains of Vermont
Read about our on-farm butcher shop project:
http://SugarMtnFarm.com/butchershop
http://SugarMtnFarm.com/csa


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## Old Vet (Oct 15, 2006)

The cast iron can be wielded or brazed. Use a nickel rod to weld with or use a bronze rod to braze with. Drill a hole at each end then get it hot and weld or braze it. I have done both numerous times and it always works for me.


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## foxtrapper (Dec 23, 2003)

suitcase_sally said:


> I, too, have heard that it can be welded, but it takes a bit more expertise than what I have to do so.


No, it doesn't. If you can strike an arc, you can weld cast iron. Pick up the nomacast rod and do the job. It's made to weld dirty, rusty, cast iron without preparation.

Not a case of "I've heard", I weld cast iron, and this is the rod I prefer.


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## celticfalcon (Jan 7, 2005)

without a pic its hard to say.it can be welded if you know a good welder.it depends on how big the crack is.IMO over 3 in is not worth it as your integrety(sp) will be comprimised(sp again)
tom


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## soulsurvivor (Jul 4, 2004)

We have an old Warm Morning woodstove that we bought new 28 years ago. It's been of good service for us but we've had to give up on the repair of a major crack that showed up a few years ago in the bottom of the stove. We've had it repaired but it's still not a secure situation for inhome use. We have a friend that wants it to use in his dirt floor shop and we haven't yet decided to allow even that. We're considering selling it for scrap metal to be certain it's not improperly used and ends up burning down a building somewhere or gassing someone to death. 

I guess what I'm trying to say is that as much as it hurts to give up an investment in a woodstove, safety has to come first and foremost with any decision that's made. There's no price that can be attached to a human life.


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## ET1 SS (Oct 22, 2005)

Cast iron is extremely hard to weld.

Back in the day, the prefered method of fixing cast iron was low-temp brazing.

However in the future as the cast iron heats and cools, it will expend and shrink again.

There is no way to get a braze joint to conform to that kind of expanding and contracting.

Drilling holes may releave some of the stress at those points.

I recommend a CO monitor, just to be safe. We have one.

This winter we bought a brand new cast-iron pot-belly coal stove directly from the manufacture.

It cost us $800, and it is rated at 200kBtu.

They are not horribly expensive.

I would say for you to simply buy a new one.


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## suitcase_sally (Mar 20, 2006)

soulsurvivor said:


> There's no price that can be attached to a human life.


I know some people that aren't worth a nickle.


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## Beeman (Dec 29, 2002)

You could probably seal it with stove cement which is what they should have sealed the pieces together with when assembled.

You said it's a Franklin stove and in my mind I see an inexpensive cast iron stove. Then later you ask about a stove for close clearances which I would guess a Franklin isn't.


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## Cabin Fever (May 10, 2002)

While I agree that every home should have a CO monitor, there is really no reason why you need one more now just because you Frankin Fireplace has a crack in it. A Franklin Fireplace has "cracks"....or should I say "leaks"....all over the place. It is not an airtight stove and the doors do not seal. Consequently, CO has plenty of places to escape a Franklin Fireplace even without a crack...even when brand new. Since a Franklin Fireplace is not air-limited, I doubt if one would even produce significant amounts of CO.

With that said, it's still a good idea that every home have a CO monitor.


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## Andy Nonymous (Aug 20, 2005)

While I'm sure a new stove would have a lot of advantages, hardly anyone I know could afford even 3 Franklins for a new one. We do what we can with what we have for as long as possible and necessary.

I have a wood stove I picked up cheap in 1978, used once (improperly) and with a crack in the bottom, running from the front edge in about an inch and horizontally about 3". I took the stove apart, drilled the inside end of the crack, warmed the area very well with an Oxy-acetylene torch with a rose-bud tip, then welded it with a high-nickel rod. Re-heated the area with the torch to help release welding stresses, and let it air cool. I ground down the face to match, reassembled the stove, put on stove black, and it held for 12 years of use, then the crack started becoming visible on the edge again, but hasn't gone further than about an inch (which is outside the stove anyway) in all the years since. It's heating the house even as I type this.

I would NOT use an epoxy (such as JB Weld) as the heat of a stove will destroy it and very likely give off some really noxious fumes. 

"Stove cement" is a misnomer, as it doesn't really give structural integrity to broken metal. It is intended to fill gaps between stove panels that are otherwise held in place by bolts. A break in a panel needs to be mended with metal, whether that be braze (which I personally haven't had much luck with) or weld. 

I disagree with FBB, as it is carbon steel that has 'temper' that is affected by the way it is heated and cooled. A chunk of ordinary cold rolled steel, heated to a "red" heat and quenched in oil will develop a "temper" of about a shovel - you can cut it with a file, but it will be 'hard'. Heat it to orange and air cool it, and it will be 'soft' again. Steel at an orange heat will readily bend or sag - cast iron does not. It has to do with molecular structure and crystalline stability. 

Cast iron, unless severely overheated and carbonized, does not develop 'temper' as we think of with steel, which is an alloy of iron, carbon, and often other ingredients these days, such as molybdenum, tungsten, chrome, nickel, etc. depending on it's intended use. It's a fascinating and complex science.


As was mentioned above, very thin castings (less than 1/8th inch) may not be worth attempting to fix as a weld may be stronger than the surrounding metal, and the stresses from the weld may cause more cracks near by. Being at the top of the stove, I'd drill the working end of the crack (with a 1/8" bit) and use a daub of stove cement to fill the hole, at least until heating season was done.

Still, for the investment of a few bucks in one nomacast rod (3/32", not 1/8") and a little gas for a torch, you could possibly fix it well for another few (or more) years of use.


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