Stainless Steel Fireboxes
Most are so thin; 1/16". Picture how thin a 1/8" drill bit is and realize that most stainless fireboxes are HALF that thickness!
Many companies have warnings on them about throwing wood in and damaging these thin and apparently fragile fireboxes.
We started replacing other brands that had fireboxes stainless Steel about 5-years after they went into production. People were telling me that water was gushing in and killing the fire! They could not find anyone that could repair stainless and no one knew how to retreat it afterwards! (RE-anneal it). You see, heated and repaired Stainless just turns into regular steel...
Here are some comments from purchasers and users of
various wood stoves and from people in the
metal and welding industry.
Jun 17
Stainless steel is not corrosion proof but it is corrosion resistant. In some cases, against some chemicals, stainless steel is no better than plain steel. It is also true that some chemicals can reportedly leach the chrome out of stainless steel (if there is any - in that grade of stainless).
Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ
September 17
We own a stainless model and after 5 years the 10 year warranty was a joke just try to collect. its a discarded junk heap is it the stainless I have been welding lots of steel stoves for pitting but never seen one crack .
Clayton Brinkman
- Kenora, Ontario, Canada
Nov 3, 2018
...High nickel stainless expands and contracts too much.
Carbon steel will transfer the heat better than stainless though.
Hope this helps
Dale Andrews
Southern Comforts - Dinwiddie, VA, USA
,
Nov 1, 2018
Just to set the record straight on stainless steel, it doesn't work in an outdoor use. It can't account for the rapid temperature changes. I am only starting to get into the heating business and I already know that stainless steel is a nice concept but when you have a cracked water jacket and there is know way to fix it, don't come crying to me.
Also I love reading about all these companies with there lifetime warranties who have only been in the business for 3-5 years, give me a break. As soon as one claim comes in they go bankrupt and your on your own once again.
Mild steel is a metal that works and if you have half a brain to take proper care and daily maintenance of your furnace it will last you. Thanks for your time.
Tim Suderman
Heat Innovations - Winkler, MB, Canada
< Stress cracks in Stainless Steel
Nov 12, 2018
Definitely go with the mild steel when you buy an outdoor wood furnace. I've seen both in use and the mild steel will not have the corrosion problems that the stainless steel has. I currently own a (wood furnace) with mild steel and I can give my testimony that it has worked perfectly and has needed no maintenance or upkeep for any type of problems. I don't speak from a "metallurgy" knowledge, but from practical experience that has done me well.
Bill Kurtz
- Fort Wayne, IN, United States
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Jan 16, 2018
I HAVE SEEN MILD STEEL UNITS, SIXTEEN YEARS OLD. UNDERSTANDING THE PHYSICS OF WHAT CAUSES CORROSION IN THESE TYPES OF METAL IS KEY. WATER ABOVE 175 DEGREES DOES NOT HAVE AVAILABLE OX. FOR CORROSION. MOST OF THESE UNITS RUN AT 180 - 185 DEGREES. 304 STAINLESS IS EXTREMELY PRONE TO STRESS CORROSION CRACKING - WHICH RESULTS FROM CHLORIDES IN THE WATER REACTING WITH THE NICKEL CONTENT OF THE STEEL. THIS IS NON-REPAIRABLE BY WELDING. 409 STAINLESS WILL GIVE YOU THE HEAT TRANSFER ABILITIES AND EXPANSION PROPERTIES OF MILD STEEL, IT IS A FERRITIC STAINLESS, SO THE SURFACE WILL TARNISH. THE CORROSION RESISTANCE IS STILL GREATER THAN MILD STEEL. ... KEEP IT SIMPLE.
JERRY SOBOCINSKI
- MEMPHIS, MI, USA
This photo shows the thinness of a typical stainless Steel Firebox; just 1/16 of an inch.
The industry standard for a steel firebox is four times thicker at 1/4"
Hyprotherm's STANDARD firebox is 50% thicker at 3/8"
Hyprotherm's Heavy Extreme Duty Firebox is a whopping HALF INCH THICK, for only $399, as demonstrated by the far right drill bit's size!
As you can see from these two charts, the expansion rate of stainless steel is very high (about 1/3 more; 0.42: vs o.28") which explains the cracks that always happen with expansion and contraction.
You also see that the conductivity of mild steel is much better - up to THREE TIMES BETTER with our carbon steel than 304L and "titanium enhanced" stainless steel. This means faster heat transfer into your water.