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Author Topic: 409 SS vs. Mild Steel  (Read 5948 times)

tinfoilhat2020

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409 SS vs. Mild Steel
« on: December 13, 2014, 07:24:28 AM »

Hey guys,

I am looking to upgrading to bigger boiler for next season. We plan on adding another dog kennel facility and our current OWB wont be enough. I currently am running a TimberWolf 5000. all 1/4 mild steel running on natural convection. My neighbor has a Heatmore. Im guessing its the 400, the things is huge. He is 70yrs old and is on his 12th year with the stove with ZERO issues. I walk over and load a nice 4ft log for him in once per day. Its seems to be a very efficient and well running stove for him. I am was very weary of anything made of SS, but seeing him stove in action and hearing his word on how good its been on him has changed my mind a bit. Ive been dead set on only mild steel construction for years, until now. CAN ANYONE ELSE PLEASE SHARE THEIR EXPERIENCE WITH THEIR UNITS?? good and bad? anyone leaking or cracking issues with the SS?

Thanks in advance!

Dylan :thumbup:
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Jwood

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Re: 409 SS vs. Mild Steel
« Reply #1 on: December 13, 2014, 08:58:54 PM »

They are good stoves but definatly not efficient, I know alot of people who have them and love them.
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AirForcePOL

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Re: 409 SS vs. Mild Steel
« Reply #2 on: December 13, 2014, 09:59:15 PM »

From my research I would say that you will only run into problems with 304 stainless but even then, it's all about how you take care of the stove.  Hardy uses 304 stainless and it's extremely thin which is great for transferring heat.  The downside is that if it overheats and boils over it CAN cause spider web cracking that would be almost impossible to fix without replacing the firebox.  You get the best of both worlds with 409 stainless.  It can still be thinner than most mild steel firebox's but with better protection against corrosion.  With the proper use of water treatment, mild steel shouldn't be an issue though and it's still critical to use treatment in stainless boilers in my opinion.   I say find a design that you like and either way if you take care of the stove it will take care of you. 
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mlappin

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Re: 409 SS vs. Mild Steel
« Reply #3 on: December 14, 2014, 05:59:14 AM »

Not only that, while 409 is one of the easiest to work with, it still requires a tad more to weld than mild steel. I haven't followed this up yet, but I seen somewhere if you're welding it they recommend preheating it to 150-200C then annealing it at 800C. Not the easiest thing to do if you need to repair a boiler made out of 409.
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yoderheating

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Re: 409 SS vs. Mild Steel
« Reply #4 on: December 14, 2014, 07:38:13 AM »

 I have sold hundreds of furnaces built with 409 and have had very very few problems.
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mlappin

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Re: 409 SS vs. Mild Steel
« Reply #5 on: December 14, 2014, 03:38:42 PM »

I have sold hundreds of furnaces built with 409 and have had very very few problems.

Oh I'm sure, and I'm also sure the manufacturers have all the tricks figured out how to properly form and weld 409, for the average or even above average person working out of their garage or shop, 409 may not be the best choice compared to common ole mild steel.
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tinfoilhat2020

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Re: 409 SS vs. Mild Steel
« Reply #6 on: December 14, 2014, 05:33:00 PM »

Thanks guys. I appreciate the input
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yoderheating

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Re: 409 SS vs. Mild Steel
« Reply #7 on: December 14, 2014, 05:34:54 PM »

I have sold hundreds of furnaces built with 409 and have had very very few problems.

Oh I'm sure, and I'm also sure the manufacturers have all the tricks figured out how to properly form and weld 409, for the average or even above average person working out of their garage or shop, 409 may not be the best choice compared to common ole mild steel.
Yes I wouldn't recommend building a home made furnace out of 409 unless you were a very experienced welder/fabricator.
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lindnova

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Re: 409 SS vs. Mild Steel
« Reply #8 on: December 14, 2014, 07:11:05 PM »

9 years on my Heatmor 200.  No problems. 

Fairly efficient.  Works the best with 24" large split pieces or up to 10" dry (<25%) rounds and if overloaded or wet wood seems to waste a lot of heat up the stack.

I had to replace the fan at 6 years.  I also added insulation on the doors and top.
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crankshaftdan II

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Re: 409 SS vs. Mild Steel
« Reply #9 on: March 07, 2015, 06:23:14 AM »

Purchased a Woodmor 400 last year with the S/S 409 interior-this was a older unit and the previous owner looks to have taken good care(water treatment and good maint.)  I don't know how this compares to mild steel units?    I purchased the unit to heat with and the only thing that I noticed was the back, removable clean out plate(Mild steel-not s/s-3/16") was eroded thru in several spots from the fly ash setting in the exhaust tubes in down time(Summer)--this door even had a thin piece of waffle type insulation against the fly ash side which did not prevent erosion!  I'm currently trying to find a 1/4" thick piece of 409 s/s to replace this with-checked all the salvage yards in my area to no avail--most stuff they get in is restaurant grade(309) which is much thinner.  I think the 8" exhaust tubes in my unit are made from 409 s/s as they look to be in excellent condition when cleaned out and inspected.   Don't know if this helps your decision making process?
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crankshaftdan II

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Re: 409 SS vs. Mild Steel
« Reply #10 on: March 07, 2015, 06:25:20 AM »

Purchased a Woodmor 400 last year with the S/S 409 interior-this was a older unit and the previous owner looks to have taken good care(water treatment and good maint.)  I don't know how this compares to mild steel units?    I purchased the unit to heat with and the only thing that I noticed was the back, removable clean out plate(Mild steel-not s/s-3/16") was eroded thru in several spots from the fly ash setting in the exhaust tubes in down time(Summer)--this door even had a thin piece of waffle type insulation against the fly ash side which did not prevent erosion!  I'm currently trying to find a 1/4" thick piece of 409 s/s to replace this with-checked all the salvage yards in my area to no avail--most stuff they get in is restaurant grade(309) which is much thinner.  I think the 8" exhaust tubes in my unit are made from 409 s/s as they look to be in excellent condition when cleaned out and inspected.   Don't know if this helps your decision making process?

I tried to post a picture of the part in question on the previous posting and the site said it was full???
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userdk

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Re: 409 SS vs. Mild Steel
« Reply #11 on: May 08, 2015, 09:26:10 PM »

.409 is my opinion.
1. Heat Tolerance
     .409 can tolerate heat up to 1400*F while .304 and mild steel begin to oxidize at only 800*F
2. Corrosion Resistance
     Stainless Steel is stainless because it has chromium oxide film layered on the steel. This film keeps oxygen from penetrating and corroding the material (rusting). This is why you see mild (carbon) steel rusting while sitting out in the open. Mild steel will start slowly corroding away from the first day of it’s use. This is why many mild steel furnaces are at least 1/4” thick (to try to give the more life span).
2. Heat transfer
     Why .409 instead of .304? It has 60% better heat transfer.
4. Strength
     Titanium enhanced to better withstand expansion, contraction, and wear and tear.
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heat550

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Re: 409 SS vs. Mild Steel
« Reply #12 on: May 09, 2015, 11:55:14 PM »

Hey guys,

I am looking to upgrading to bigger boiler for next season. We plan on adding another dog kennel facility and our current OWB wont be enough. I currently am running a TimberWolf 5000. all 1/4 mild steel running on natural convection. My neighbor has a Heatmore. Im guessing its the 400, the things is huge. He is 70yrs old and is on his 12th year with the stove with ZERO issues. I walk over and load a nice 4ft log for him in once per day. Its seems to be a very efficient and well running stove for him. I am was very weary of anything made of SS, but seeing him stove in action and hearing his word on how good its been on him has changed my mind a bit. Ive been dead set on only mild steel construction for years, until now. CAN ANYONE ELSE PLEASE SHARE THEIR EXPERIENCE WITH THEIR UNITS?? good and bad? anyone leaking or cracking issues with the SS?
Thanks in advance!

Dylan :thumbup:

Read here it will shed some light on real world reviews .
https://www.furnacecompare.com/wood-furnaces/ratings.html

I had a heatmor 200css for 19 years heatmor put to the test . Its heating 2 houses and shop and garage . 5500spft .
Burned oak 5.5 billion Btus in the 19 years . Your neighbor knows Im getting a bigger 400css soon . :thumbup:

heat550

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