Soapstone or fire brick ?
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Highbeam
Minister of Fire
Since you have this choice I assume you are looking at buying a woodstock?
Myself, I would rather buy firebrick. I owned a soapstone stove with stone against the fire and it took a long time to warm up. Is there a cost difference?
Myself, I would rather buy firebrick. I owned a soapstone stove with stone against the fire and it took a long time to warm up. Is there a cost difference?
Standard Firebrick:
Cheaper
Not that much difference in reality for its heat retention ability
Soapstone is more apt to crack & break
Soapstone must be VERY carefully selected to stand up to the high temps (Do not attempt to use counter-top grade stone in your stove, as it will just crack-up & break apart)
(Despite the success of one or two manufacturers use of soapstone, my personal opinion is that soapstone belongs on the outside of a wood stove, not on the inside -- as a general rule)
(We are talking standard firebrick here, not the super light-weight pumice type)
No,I own the hearthstone Mansfield and think about changing the firebrick.Since the stone heats up it gives off heat even after the fire is out.I'm thinking with the soapstone brick it would even give off more and a longer heat output.
If you should try to do this -- buy the soapstone from a distributor that specifically sells them for the fire-box -- either stove or fireplace. Otherwise, I'll guarantee they will not last. In reality you will not gain that much retention.
Highbeam
Minister of Fire
I know my heritage had zero bricks. The stone slabs on the inside of the firebox were the same slabs as the outside. Do you suppose somebody added bricks? Did the Mansfield have them?
VirginiaIron
Minister of Fire
I would tend to agree since the heat from the firebox has left the chamber into the living space to heat the stone rather than heating the stone within the firebox, as an insulator, and the heat traveling up the chimney.
I don't believe the Mansfield has any firebrick either. Someone must have added some. That's a sure way to slow down an already struggling heater.
It depends on what thermal property you're looking for.
Soapstone is good at storing heat energy, meaning its a good thermal conductor and not an insulator. This is why soapstone gives off heat after the fire has gone out. Firebrick on the other hand does not store heat energy, meaning its a good insulator and reflects heat energy back to the source (fire).
My opinion is that engineers used various assumptions in the design and manufacturing process of the stove itself given whether stone/brick was used.
Soapstone is good at storing heat energy, meaning its a good thermal conductor and not an insulator. This is why soapstone gives off heat after the fire has gone out. Firebrick on the other hand does not store heat energy, meaning its a good insulator and reflects heat energy back to the source (fire).
My opinion is that engineers used various assumptions in the design and manufacturing process of the stove itself given whether stone/brick was used.
electrathon
Minister of Fire
A good conductor can quickly absorb heat and then quickly can release it (think aluminum). Soapstone is a poor conductor. Soapstone is good for thermal mass heat storage. Far, far different from thermal conduction.
In this example the firebrick insulate the bottom of the stove to keep heat away as a means of stove protection. The heat is not absorbed, just moves a different direction. With soapstone, the heat would mainly go away, but some would be absorbed into the stone. This would raise the bottom temp of the stove. Making a little more heat exit the stove into the room. It would also alter the safe distance to combustibles under the stove. Ash build up would help with the safety issue, also nullifying any gains from the stove.
Gee now that you mention it you got me guessing.I sent an e-mail to hearthstone about my question.As soon as they get back to me I'll get back to all.
electrathon
Minister of Fire
You could look in the stove. I don't think there are any in mine, you see the soapstone on the sides when you look into the firebox. The bottom is the ash grate. Not sure about other models or years manufactured.
I'm looking at one right now. The floor has a layer of 1 1/4" soapstone bricks, they are cemented down. After some use they might loosen up, could just be some slag cement locking them down.
jetsam
Minister of Fire
Soapstone has a very poor thermal conductivity, but a high thermal capacity. Firebrick is a little worse at capacity, and much worse at conductivity.
As a firebox liner, you're probably slightly better off with soapstone, but it's not a difference you'd really notice.
If you're considering crippling your stove by putting soapstone panels on the outside- unless you live in southern Florida or plan to give the stove big yummy hugs while it's burning, reconsider.
As a firebox liner, you're probably slightly better off with soapstone, but it's not a difference you'd really notice.
If you're considering crippling your stove by putting soapstone panels on the outside- unless you live in southern Florida or plan to give the stove big yummy hugs while it's burning, reconsider.
toddnic
Minister of Fire
Here is some data regarding soapstone and firebrick from http://www.traditionaloven.com/articles/691/soapstone-data-info. There is a lot of information on this website beyond what I pasted below.
Soapstone vs. firebrick comparisons
Here we compare soapstone with refractory properties of firebricks which contain:
33% Aluminum
63% Silica
1.2% Ferric oxide
1.2% Titania
1.6% Accessory oxides
For comparison – 33% alumina + 63% Silica firebrick properties
Thermal Conductivity :
Soapstone has higher thermal conductivity 12.5 W/m • °K than the 33% alumina content grade firebrick which is at 9.15 W/m • °K in comparison with the two materials. The soapstone has roughly three times (~3x) the bulk density 2.95g/cm3 … these firebrick types have 2g/cm3. Meaning soapstone has also heavier mass.
Conclusion
The specific heat capacity of the soapstone comes to 785.2 J/Kg.°K where the firebrick is at a lower 757 J/Kg.°K heat storage. All is calculated @ room temperature level. Soapstone wins, it collects slightly more heat and gets hotter as well.
Soapstone vs. firebrick comparisons
Here we compare soapstone with refractory properties of firebricks which contain:
33% Aluminum
63% Silica
1.2% Ferric oxide
1.2% Titania
1.6% Accessory oxides
For comparison – 33% alumina + 63% Silica firebrick properties
Thermal Conductivity :
- Alumina – Al2O3 thermal conductivity at r.t. is 25.08 W/m • °K = 8.2764 per 33%
- Silica – SiO2 thermal conductivity at r.t. is 1.38 W/m • °K = 0.8694 per 63%
- 33% Alumina firebrick thermal conductivity – SiO2 63% + Al2O3 33% = 9.1458 W/m • °K
- Alumina – Al2O3 specific heat at r.t. is 880 J/Kg • °K = 290.4 per 33%
- Silica – SiO2 specific heat at r.t. is 740 J/Kg • °K = 466.2 per 63%
- 33% Alumina firebrick specific heat – SiO 67% + Al2O3 33% = 756.6 W/m • °K
Soapstone has higher thermal conductivity 12.5 W/m • °K than the 33% alumina content grade firebrick which is at 9.15 W/m • °K in comparison with the two materials. The soapstone has roughly three times (~3x) the bulk density 2.95g/cm3 … these firebrick types have 2g/cm3. Meaning soapstone has also heavier mass.
Conclusion
The specific heat capacity of the soapstone comes to 785.2 J/Kg.°K where the firebrick is at a lower 757 J/Kg.°K heat storage. All is calculated @ room temperature level. Soapstone wins, it collects slightly more heat and gets hotter as well.
JA600L
Minister of Fire
My stove has soapstone firebrick. It takes forever for it to cool down after the fire goes out. Also, coal retention is much better than any other stove I have ever used.
I much prefer a stove that throws as much heat as needed. I don't like waiting for it to slowly build up temp. I know, it has "heat life" but so what, a 180 degree stove doesn't come close to cutting it here in the winter. I load the stove in cycles, a full load lasts me 24 hours, if I need more heat I just crank it up, with almost instant results. It might bring my burn times down to 14-18 hours, still better than any stove out there! Soapstone, been there don't that, now I'm soaking up the real heat!
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