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[Scott7m]

we've all been led to beleive our whole lives that stainless is a superior metal for most all applications.  Most never look into the different grades of stainless.  The titanium enforced stainless 409 is what i'm questioning.

I would like to have a stainless stove to offer those who are hung up on stainless but what can anyone tell me about 409 stainless. 

[yoderheating]

 409 is the best I have found for building furnaces. It has a high level of corrosion resistance and doesn't have the cracking problems that 304 has.  409 isn't fool proof, it can pit if improperly maintained but it is much better than mild steel.  I have yet to have a furnace leak since we started selling HeatMaster furnaces built out out of 409. I'm sure everyone has a different opinion about the best metal, I can only speak from what I have seen.

[willieG]

I would like to have a stainless stove to offer those who are hung up on stainless but what can anyone tell me about 409 stainless.
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don't know anything about metalergy (if thats the word) but i go by what things are worth asi build my own stuff when i can and as of today in my neck of the woods, at the scrap yard prices are as follows stell is 190 bucks a ton. 300 grade stainless is 1364 bucks a ton and 400 series stainless is 154 bucks a ton. my thinking may be entirely wrong but it looks to me as though 400 series stainless would not be my metal of choice as the price leads me to believe it is not as good as steel.

Also i have been told (only hearsay) that car mufflers are built from this grade of stainless...and they don't last that long

again i may be totally wrong on this but thats my 2 cents

perhaps a metalergry man can shed some proven truths on this subject?

[yoderheating]

  I don't claim to be an expert by any however I spoken to experts on the matter. From what I can gather 304 has a much higher level of chrome ( the reason for the higher cost). 304 also has a thicker scale than 409 does giving it more protection against corrosion.  However there are several down sides to using 304 in this application.  304 does not conduct heat as well as 409 or mild steel. 304 is prone to chloride stress corrosion cracking and 409 is not.  The scale and base of 409 have the same characteristic where in 304 they are different, this may allow the two to begin to separate over a long period of heating and cooling. 
 The best operating furnace would be a very thin mild steel furnace but durability would be an issue.

[willieG]

sounds like it could be true...if not, you are fooloing me..lol

so if you build a stove from 400 series and the junk price between mild steel and 400 is not that much (in fact mild steel is more at the junk yard) then a 400 series stove should be cheaper than a mild steel one??

[yoderheating]

 I am only passing along info that I have been told by someone who works in steel sales. I assume he is telling me the truth but I would love to read what others have to say on this. After all, we all want to know how to make the perfect furnace.
 On the subject of price, a mild steel furnace normally is twice as thick as a stainless furnace so I would assume it may cost more. I have a list of metal cost from a few months ago around somewhere but I can't seem to lay my hands on it.
 I find it interesting that while the subject of types of metals often include corrosion they often do not include the ability of the same metal to transfer heat. For instance, 409 is twice as resistant to transferring heat as mild steel so to have a comparable furnace it must be half as thick. 304 is even more resistant so it would need to be even thinner.
I find all of this to be fascinating. I am very glad that furnace manufacturing is moving into this more complex stage of production. Gone are the days that a manufacturer can spit out a box made of almost anything and sell it as a quality product. The more testing and refining of theories of corrosion and efficiency the better.

[Scott7m]

409 is def the cheap stuff when it comes to steel, doesn't mean it won't work.  Just wanted to hear some opinions!

[yoderheating]

What are Natures Comfort make them out of ?

[Russ Brumit]

  I almost bought this stove .  I really liked it but it was expensive. Saw it in operation. Looked very nice. 409 stainless seemed like a good way to go . Check it out.

    http://www.heatmor.com/index.html

[Scott7m]

Natures comfort are made of 1/4 and 3/8 mild steel.  They are very heavy built, the 175 model which is the most common is almost 1900 pounds.  The welding looks professional as well.  I've also talked with the rep for heatmasterss and can get one of those if someone is wanting stainless. 

[juddspaintballs]

My parents have a Heatmor and I'm currently installing mine right now.  They love theirs so I bought the same one.  One of the biggest advantages I see to Heatmor's firebox over some other ones that I see is not the 409 stainless, but actually that the firebox floor is not metal at all.  It is lined with firebrick and packed with sand that way the ash cannot corrode anything down there and it also acts as thermal storage mass for keeping the water in the jacket warm longer.