stainless firebox

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Is there a wood gasification log boiler manufacture who builds their primary firebox out of stainless steel?
 

E Yoder

Minister of Fire
Jan 27, 2017
551
Floyd, VA
HeatMaster is all 409 stainless, firebox, water jacket, tubes, doors, etc.
 

E Yoder

Minister of Fire
Jan 27, 2017
551
Floyd, VA
I can remember the stainless v. mild steel debate being hotly debated for quite some time.
What I've seen- most of the outdoor style wood boiler manufacturers were either using 409 SS to start with or moved that way in the last few years. Mild steel is used for some in the outer water jacket where it doesn't contact the creosote/moisture in the firebox and flues.
304 SS has been mostly dropped as it expands more and can crack. 409 expands similarly to steel.
Someone feel free to correct me, I'm just thinking through the wood boilers we have down here in VA.
 

Case1030

Feeling the Heat
Dec 12, 2017
363
Manitoba
I recently bought a Polar G-class they are using 304 SS for the firebox 3/16 thick.

All research that I have done, being that I previously owned a Heatmaster... I noticed most boilers made with 409ss are only 1/8 = 2/16. Maybe @E Yoder can confirm?

Also 304ss is more costly but comes with it's advantages. It's non-ferromagnetic very good corrosion resistance (no pitting). You can google some pictures to see for yourself.

It is true 304ss has higher thermal expansion, but that's at extremely high temperatures. (Easy to confirm through Coefficient of Thermal Expansion.)
The firebox doesn't burn wood in the upper chamber... the refractory brick underneath is where the intense flame takes place with all of the heat.

Both boilers are good just thought I'd clear that up, as I had the same thoughts before looking into it.
 

JRHAWK9

Minister of Fire
Jan 8, 2014
1,674
Wisconsin Dells, WI
I know Lamppa uses 304 SS and 310 SS for all the parts -inside- their firebox and even has spots where the 304 is welded to mild steel (the lower back wall).

Some old photos of my 2014 model when new.

Top of firebox, all 310SS:
IMG_0901.JPG

Front wall directly under loading door. Shown is 304, but they started using even thicker 310SS a few years ago I guess :
IMG_0898.JPG


Granted this is not a boiler and doesn't have to store water, but where the 304SS pieces are in the upper chamber of the firebox are where some of the highest temps are in this furnace as that's where the majority of the gasses are being burned at.
 

E Yoder

Minister of Fire
Jan 27, 2017
551
Floyd, VA
You are correct, Heatmaster uses 10 g. 409 approx 1/8”.
My experience with 304 was with the Hardy units which I think was 14g, quite thin and tended to crack. Polar sounds like a different animal.
 
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