# regular and light weight firebrick differences



## skidud (Oct 16, 2012)

Can someone tell me the differences between the light weight and the regular fire brick?  My manual calls out the use of both and I noticed that the last owner had them installed in a different order than the manual states.  I guess I'm interested in knowing which one insulates better and what kind of difference there would be if one were swapped for the other.  Thanks


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## FyreBug (Oct 16, 2012)

The insulation qualities of either are almost identical. The heavier refractory bricks however will last year's if not decades. Whereas softer pumice bricks might only last you a couple seasons or more depending on usage.


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## skidud (Oct 16, 2012)

I read somewhere that the pumice bricks were better and worth the shorter lifespan.  I guess I couldn't figure out the actual difference besides they were softer and had shorter lifespans.  I also wasn't sure if the pumice bricks were indeed what my manual refers to as light weight.  I'll have to do some research on pumice bricks then.  I've got enough of either to completely reline the stove but want to use the best brick.


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## BobUrban (Oct 16, 2012)

Not sure if one is better insulating than the other but we use both in our forge and it gets in the 2000 degree range.  I do know when I am heating finished blades for normalizing and heat treat I use a small chunk of either to keep the blade off the forge floor for more even heat.  If I leave a small piece in the center of the forge it will melt - no matter which type I am using


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## Todd 2 (Oct 16, 2012)

The light ones came in my summit new, the third season they started to powderize and break ( bumping them with bigger splits when loading full ) Installed the heavy solid clay ones and they seem to be much more durable ( the dealer said they would last alot longer. The only difference I can tell is that with the new heavy ones the stove seems to take a little longer to heat up on cold starts, but on the plus side the stove seems to be warmer at the end of the burn cycle. 20 - 25 deg. warmer surface temp. They don't move around when you catch the edges of them with your ash shovel or chip as bad as the light ones either. As far as installing them I followed the mfg. instructions, one would think that is how they tested them and maby gives the best fire box protection & performance. As far as insulating, I can't really tell any difference.

What part of northern OH Skidud ?


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## precaud (Oct 16, 2012)

FyreBug said:


> The insulation qualities of either are almost identical. The heavier refractory bricks however will last year's if not decades. Whereas softer pumice bricks might only last you a couple seasons or more depending on usage.


 
Now that is a flat out lie, and from someone who knows better. Spare us further displeasure and correct your own mistake.


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## begreen (Oct 17, 2012)

Our pumice bricks are going on 4 seasons and still look good. I don't have the numbers but I thought they have a significantly higher insulative value due to the trapped air in the pumice.


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## oldspark (Oct 17, 2012)

." Hardbricks are very dense
and durable and used for their structural
qualities. They can be found most often as
the main building component of large kilns,
chimneys, fireboxes and burner ports—anywhere
around direct flame. Softbricks are
lightweight and made from a refractory
clay body containing combustible materials.
When fired, the materials burn out
leaving a sponge like matrix of air pockets,
which serve to provide insulating qualities
to the brick. Also known as insulating firebricks
(IFBs), these bricks absorb about half
the energy as hardbricks during a firing.
Softbrick range from 2000°F to 3300°F
and are used as the brick of choice for constructing
electric kilns or as insulating liners
in reduction kilns."


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## Jags (Oct 17, 2012)

Ummm...still on the original pumice bricks (8 yrs).  "A couple of seasons" may not be accurate. And YES, there IS a difference in the absorption and reflective properties of the two types of bricks.


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## precaud (Oct 17, 2012)

begreen said:


> I don't have the numbers but I thought they have a significantly higher insulative value due to the trapped air in the pumice.


Yes, by a factor of 4 to 6 over the clay firebricks. And as I've pointed out many times, the high thermal mass of clay bricks works further against their effectiveness in a place where low-mass, high-isulation factors are needed. Clay bricks are used solely for economic reasons, not for performance.


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## FyreBug (Oct 17, 2012)

Some facts regarding bricks:

K factor for either pumice or refractory almost identical
Heat transfer for either almost identical
Heat retention is much better for refractory due to its mass
Mechanical properties much better for refractory
Weight of pumice about 1/3 of similar size refractory
Cost of pumice about 1/3 less than refractory
I can post the MSDS if you'd like. 

Why would a MFG use pumice vs. refractory? 1) On a larger wood stove you save almost 50Lbs in shipping weight. You can therefore cube out before you weight out. ie. saves on shipping. This is particularly important for imports 2) Cost: Obviously there is cost savings associated with the brick itself.

Since we use both, we are well aware of the properties of either. We use the lightweight bricks for our 'value' brands and the heavier for our premier brands.


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## madison (Oct 17, 2012)

Thanks for the info FyreBug and all responders.

4th or so season with the OEM soft brick with my T6, after the first yr, the bricks in front of the stove (@ the air inlet) started to deteriorate and now have lost ~ half of their thickness, I have flipped and rotated these with the rear and side bricks. I picked up some hard bricks at Tractor Supply for replacing, but have not used them yet. I will try these heavier bricks in the front in the future...

Soft bricks are not locally available .


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## precaud (Oct 17, 2012)

FyreBug said:


> Some facts regarding bricks:
> K factor for either pumice or refractory almost identical


 
When I looked into is a couple years ago, normal "refractory" firebrick K factors were between 4 and 15, with ones used in stoves averaging about 5.5
Pumice and other IFB were in the 0.88 to 1.1 range. That's hardly identical.



> Heat transfer for either almost identical
> Weight of pumice about 1/3 of similar size refractory
> Heat retention is much better for refractory due to its mass


 
If they're the same size yet 3 times the weight, then heat transfer cannot be identical.
And why does one want "heat retention" in a firebox lining? In reality, the insulating properties of the liner become undesirable as soon as the flames die, just like secondary air. The more heat "retained" in the firebox, the more is carried away up and out the chimney, due to the "always-on" air systems.



> Mechanical properties much better for refractory


 
Directly related to the weight. The higher-density IFB's are just as good, though prohibitively expensive.



> Cost of pumice about 1/3 less than refractory


 
And is that a bad thing?


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## TMonter (Oct 17, 2012)

FyreBug said:


> The insulation qualities of either are almost identical. The heavier refractory bricks however will last year's if not decades. Whereas softer pumice bricks might only last you a couple seasons or more depending on usage.


 
Not true. Pumice bricks are an insulating firebrick and the dense bricks are not. If you look at a refractory schedule for both you will find a immensely higher insulating value on the pumice versus refractory brick. (Experience from working with both products in boilers).

Dense firebrick is used for wear value, not necessarily insulating value.

I don't have the refractory schedule I used to have handy but I did find this:

http://stoves.bioenergylists.org/stovesdoc/Andreatta/Heatloss.htm

Remember maintaining a good clean burn with the secondaries on a modern stove requires that the temperatures remain relatively high. Pumice bricks are good for doing this while dense firebricks are not.


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## begreen (Oct 17, 2012)

FyreBug said:


> I can post the MSDS if you'd like.


 
Please do. And tell me where I can find pumice bricks for anywhere near 1/2 cost. Everywhere I have checked has them at about 2x the cost of common firebrick. Though you mentioned refractory which I don't believe is the same animal. Maybe we should be sure we are talking about the same products here? The MSDS will help.


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## BrotherBart (Oct 17, 2012)

FyreBug said:


> 1) On a larger wood stove you save almost 50Lbs in shipping weight.


 
What I have said here for years was probably the reason for using the things.


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## TMonter (Oct 18, 2012)

BrotherBart said:


> What I have said here for years was probably the reason for using the things.


 
But 50 lbs on something that heavy which is going freight anyway unless it's air freight, isn't going to significantly change the price unless you're at a common break point for weights.


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## FyreBug (Oct 18, 2012)

begreen said:


> Please do. And tell me where I can find pumice bricks for anywhere near 1/2 cost. Everywhere I have checked has them at about 2x the cost of common firebrick. Though you mentioned refractory which I don't believe is the same animal. Maybe we should be sure we are talking about the same products here? The MSDS will help.


 
I should have said around 1/3 less on the cost. At retail the cost differential might be around 10% 15% less. (we do anyway - dont know about other vendors)

I've asked for the MSDS but something to ponder on in the meantime... If pumice provided a distinct advantage in efficiencies and caloric values, you would think all MFG's would avail themselves of this advantage. However, many 'premium' brands despite the shipping weight disadvantage and revenue loss on replacement parts and higher cost of the heavy duty brick brings to the unit see this as a benefit. This is a Lopi video where they discuss the advantages of the heavy bricks around the 1 min. mark. 


Finally, I'm a bit puzzled by the argument against additional mass in the firebox. This is seen as a benefit for thermal mass heaters such as Tulikivi and brands such as Heartstone which line their firebox with soapstone. Not to mention cast iron stove. More mass evens out the heat curve for radiating heat for a longer time. This is typically seen as a benefit not as a detriment.


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## oldspark (Oct 18, 2012)

Well I wondered about this a couple of years ago and did not find out what I wanted to know, maybe now we will get some good answers.


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## Jags (Oct 18, 2012)

Something else to ponder (and I mean that, I don't have the answer), is it possible that the pumice style, with better insulating properties is used in places to protect the shell of the stove?  As an example - my Isle Royale only requires ember protection - no specific R value for the hearth pad.  It also uses the pumice style bricks on the bottom.  Simply coincidence or intentional?  Inquiring minds want to know.


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## begreen (Oct 18, 2012)

The video is a sideline, not on topic. Lopi has a reputation of building tough stoves. Conventional firebrick is tougher. Lopi smartly is touting this as a feature, the same way SBI boasts the toughness of it's c-cast baffles. Good marketing but a bit off topic I think.

It will be interesting to see what firebox insulation materials are used in the new stove challenge. My guess is that they will be using some more exotic thermal insulation and maybe pumice bricks. But I wonder how many will be using regular firebrick? My guess is none, but I could be wrong.


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## Huntindog1 (Oct 18, 2012)

I have recently been looking into the different brick types as some of you know I recently put a 1/4" ceramic insulation behind all of my firebrick, sides and bottom.

I was also looking into using a more insulative firebrick.

What I found is that firebrick can have a higher alumina content and are rated as such as what percentage they have of alumina in some fire brick.

As there is another aspect of firebrick that was mention and that is its reflective properties. Heat radiation can be reflected back into the fire box.

I suspect that the alumina content may point to how well it reflects heat. But it may conduct heat more , I am not sure.

Ceramic and ceramic made from alumina is said to be more highly reflective material. It also can also take more heat.

Take a look at this webpage and notice what it says at the bottom about efficiency.
http://hotkilns.com/reflective-coating

Think of your old fashioned thermos bottle had the highly reflective almost mirror like glass liner with a vacuum air space all around as in insulator.

So would it be better to use the more reflective fire brick with ceramic insulation behind it.

Insulative fire brick points to less conduction of heat , then fire brick that are more reflective points to reflecting the heat radiation back into the fire box.

As with heat you have convection,conduction and radiating heat (heat radiation).


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## TMonter (Oct 18, 2012)

FyreBug said:


> If pumice provided a distinct advantage in efficiencies and caloric values, you would think all MFG's would avail themselves of this advantage


 
But that isn't what has been claimed. It doesn't have anything to do with efficiency directly but rather keeping temperatures up in the firebox during extended burns so that the secondary burn system stays lit. If the stove is designed with insulating firebrick swapping it out can have detrimental effects on how fast the stove heats up and how it performs.


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## milner351 (Oct 18, 2012)

Interesting.  My Summit factory bricks are starting to erode, one has broken.  The vertical bricks on the sides seem to be taking more of a beating than those on the floor of the firebox.  I've been wondering what the best course for replacement would be.

Thanks for the information, I have some pondering to do.


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## FyreBug (Oct 18, 2012)

I have reviewed the MSDS, however it doesn't list any of the caloric qualities of the bricks; only the Health & Safety Hazards. I'll make a request of engineering for their comments since I would also like to get a definitive answer. However, at this time of the year they are up to their neck in projects and workload so I wont push too hard.

I will offer this comment though... Performance, BTU output, emissions etc... is the 'holy grail' of all wood burning appliances MFG and their engineers. They talk to all types of suppliers and review components performance on a regular basis in order to get an edge. Many have their own labs so they can test to their hearts content.

If a particular brick provided a significant performance advantage, they would immediately ensure to use this particular component. Instead what do we see in the market? Heavy duty bricks are favoured by many (not all) higher priced units despite weight, cost and replacement part income loss. Some of what are considered very high end will use Skamol (Scan), soapstone (Hearthstone) or a high grade of vermiculite (Valcourt).

Therefore, based on this I doubt very much the performance is enough to justify all this debate in smaller fireboxes. It could be that in larger applications such as Kiln and large commercial/industrial ovens it provides better benefits. I would also suggest the advantage of using one firebrick over the other has more to do with financial considerations than anything else. 

Keep in mind the efficiency testing is relatively easy with the 'stack loss' method. Therefore comparing either or any bricks is not a big deal and no doubt most engineers are aware of the differences if any...


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## oldspark (Oct 18, 2012)

Here's some more info-two different uses, you decide whether it makes a difference, there is a reason they use them IMHO.
"Do not confuse lightweight *insulating fire bricks* with heavy *dense firebricks*. Insulating bricks are refractory too and of course withstand very high temperatures range BUT for purpose they have very low thermal conductivity and don’t absorb the heat well at all. 

 Those are intentions for heat insulation. For instance if you used them for building of the hot face in a wood fired oven (for cooking) the oven wouldn’t cook, because it wouldn’t store and hold almost any heat. You can however use these insulating fire bricks on the outer side (of the heavy firebrick walls, vault or under the floor bricks and slab) to prevent the soaked in heat in the chamber’s body mass from escaping and achieving superb results. Meaning well insulated oven which will hold the absorbed heat in its mass, where it should be to cook for long time."


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## Huntindog1 (Oct 18, 2012)

The numbers left to right:

MaterialDensity (kg/m^3) - Specific Heat (J/kg-C) - Thermal Conductivity (W/m-C) - Estimated heat loss(MJ)

Ordinary Brick 1600 - 840 - 0.7 - 5.7
Pumice Brick 770 - 835 - 0.107 - 1.5


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## TMonter (Oct 18, 2012)

FyreBug said:


> I have reviewed the MSDS, however it doesn't list any of the caloric qualities of the bricks; only the Health & Safety Hazards. I'll make a request of engineering for their comments since I would also like to get a definitive answer. However, at this time of the year they are up to their neck in projects and workload so I wont push too hard.
> 
> I will offer this comment though... Performance, BTU output, emissions etc... is the 'holy grail' of all wood burning appliances MFG and their engineers. They talk to all types of suppliers and review components performance on a regular basis in order to get an edge. Many have their own labs so they can test to their hearts content.
> 
> ...


 
I'm of the opinion you should use the type of brick the stove was designed for. Using a denser more conductive firebrick could lead to reduced performance on some stove designs. At the very least you should try to find firebrick with similar characteristics to the ones currently in your stove.


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## Jags (Oct 18, 2012)

TMonter said:


> I'm of the opinion you should use the type of brick the stove was designed for. Using a denser more conductive firebrick could lead to reduced performance on some stove designs. At the very least you should try to find firebrick with similar characteristics to the ones currently in your stove.


 
Exactly the reason I posted my query above.  If the pumice style gives my stove more insulating value for the floor of the stove - which allows for ember protection only....will the denser brick offer the same advantage??? Could replacing the bricks with the wrong type be a clearance to combustibles issue??


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## TMonter (Oct 18, 2012)

Jags said:


> Exactly the reason I posted my query above. If the pumice style gives my stove more insulating value for the floor of the stove - which allows for ember protection only....will the denser brick offer the same advantage??? Could replacing the bricks with the wrong type be a clearance to combustibles issue??


 
It would be an interesting question to ask Quadrafire about. I would guess the type of brick has at least something to do with it.


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## Huntindog1 (Oct 18, 2012)

I like the idea of maintaining a higher temp in my firebrick lined firebox at the lowest primary air setting of my stove. I can maintain my secondary flame action at a much lower setting.
I think we all would like to be able to turn our burn tube stoves down like a cat stove can be turn down, we wont be able to go as low as a cat stove but every little bit helps.


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## bryan (Oct 18, 2012)

Ordinary Brick  0.7 W/m-C
Pumice Brick  0.107 W/m-C

A 7 fold difference in thermal conductivity seems very substantial assuming the bricks are of equal thickness.


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## begreen (Oct 18, 2012)

FyreBug said:


> If a particular brick provided a significant performance advantage, they would immediately ensure to use this particular component. Instead what do we see in the market? Heavy duty bricks are favoured by many (not all) higher priced units despite weight, cost and replacement part income loss. Some of what are considered very high end will use Skamol (Scan), soapstone (Hearthstone) or a high grade of vermiculite (Valcourt).
> 
> Therefore, based on this I doubt very much the performance is enough to justify all this debate in smaller fireboxes. It could be that in larger applications such as Kiln and large commercial/industrial ovens it provides better benefits. I would also suggest the advantage of using one firebrick over the other has more to do with financial considerations than anything else.
> 
> Keep in mind the efficiency testing is relatively easy with the 'stack loss' method. Therefore comparing either or any bricks is not a big deal and no doubt most engineers are aware of the differences if any...


 
In a smaller stove I think a superior insulator would be even more important, especially when you want to have the largest firebox in the smaller form factor. This is why they are using more exotic insulation in most European stoves. 


PS: I'm still waiting for some links for pumice bricks that are cheaper than regular firebrick. Lots of folks would benefit from these sources. Everywhere I have looked they are about 2x the price.


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## Huntindog1 (Oct 19, 2012)

If you are having trouble finding cheap insulating pumice fire brick, A while ago I exchanged some emails with John Gulland about the use of Ceramic insulation behind my fire brick.
He said he had thought about the idea to replace his pumice fire bricks with the more durable ones then use the ceramic 1/4" insulation to get the insulative properties back that he got with the pumice bricks. It took about $30 worth of ceramic insulation to do all of my stove.

If you get the fire bricks with the high alumina content , the higher reflective properties would reflect the heat radiation back into the fire. Add the insulative properties of the 1/4" 2300 deg ceramic insulation with the added reflective properties of the high alumina content fire brick, should provide a nice little performance boost in the stove especially at your lowest all night burn settings.

Being that most of the heat from a wood fire and its coals is radiated heat I suspect that firebrick with high reflective properties would do more to keep the heat concentrated at the fire.

I seen online a report of a study done on the effects of preheated secondary air verses non heated secondary air.

Secondary air heated to 500 deg provided a 7.7 percent increase in efficiency and secondary air heated to 1000 degrees provide a 23 percent increase in efficiency.

So this indicates to me that with increases in temp, makes the efficiencies  better.

Lastly I suspect that pumice bricks are required in some stoves to meet their clearance specs to walls and such. If you replace your required pumice bricks with regular fire brick then more heat will radiate out the back and sides rather than the top and front as the stove was designed thus heat your walls close to your stove to a higher level.


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## Huntindog1 (Oct 19, 2012)

I would like some fire bricks made out of this stuff.
Looks like you can buy a brush on coating.

http://www.eaglecoatings.net/video/emmissivity.html

http://www.axner.com/itc100htceramiccoating.aspx

http://www.axner.com/what-author-nils-lou-has-to-say.aspx

http://www.hightemptools.com/itcproducts.html

*ITC-100 forge refractory coating*
Invented by Feriz Delkic, founder of International Technical Ceramics, ITC-100 has been been used by the ceramics industry for over 25 years. This versatile high temperature ceramic coating can be applied to a variety of gas forge materials: ceramic fiber blanket, fiber board, refractory brick and castable refractories. In the blacksmithing and bladesmithing world, those who have used ITC-100 in their forges swear by it's value. Most homemade forges cannot reach forge-welding heat without an application of ITC-100.
*Efficiency*ITC-100 increases a forge's fuel efficiency 30 percent by reflecting 98 percent of the forge's infrared radiation.
*Safety*ITC-100 protects against respirable silica. Refractory materials like Kaowool begin to break down at 1800 degrees F. releasing a form of respirable silica known as cristobalite. When applied to fiber blanket and cured, ITC-100  eliminates this problem.
*Durabilty *ITC-100 coats the ceramic fiber blanket forming a protective shell in the forge interior,greatly extending the life of the insulation.


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## precaud (Oct 19, 2012)

Huntindog1 said:


> I would like some fire bricks made out of this stuff.
> Looks like you can buy a brush on coating.


 
I was intrigued by these coatings as well, but decided against experimenting with them. Here's why.

They all claim to work by reflecting infrared (that is wavelengths _longer_ than our visible spectrum). Look at them and you'll see they are all white in color, or nearly so. Their reflectivity is largely dependent on their color. If they were black, they would absorb visible and infrared. Inside the kilns in which they were designed to operate, they stay white, unless an accident happens.

But woodstoves are different. During the warmup stages of a fire, the stove interior (firebrick included) is covered with carbon and soot, and they stay that way until the adjacent area is hot enough to burn them clean. So during the stage of the fire when you really want the coating's reflectivity to be working to help the firebox come up to operating temp quickly, it is covered with carbon and no help at all. (Remember, for an EPA stove, the majority of the emissions occur at the beginning and end of the burn cycle.)

So I decided that coatings wouldn't be effective in a stove.


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## precaud (Oct 19, 2012)

Huntindog1 said:


> Being that most of the heat from a wood fire and its coals is radiated heat I suspect that firebrick with high reflective properties would do more to keep the heat concentrated at the fire.
> <snip>
> So this indicates to me that with increases in temp, makes the efficiencies better
> Lastly I suspect that pumice bricks are required in some stoves to meet their clearance specs to walls and such. If you replace your required pumice bricks with regular fire brick then more heat will radiate out the back and sides rather than the top and front as the stove was designed thus heat your walls close to your stove to a higher level.


 
I understand how you're concluding this, concentrating on the radiated energy. My experiments support the efficiency conclusion but the rest didn't work out that way. Increased insulation raises the temps in the firebox, with two consequences:
1. Increased firebox temps = hotter bricks = more heat conducted into the stove body = hotter stove surface temps = more heat into the room during the flaming part of the cycle. (Higher mass firebrick will lessen this gain by storing more of this heat. Not a good idea.)
2. Increased firebox temps = the wood in it gassifies at a quicker rate. This definitely can change the way a stove burns. I can imagine in some cases it being harder to control the burn rate. It can also help a stove to burn a load more completely all the way to the back of the firebox. The Jotul F602 definitely benefited from this.

So if lower numbers for clearance specs on a radiant stove is what you want, use refractory firebrick.


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## Huntindog1 (Oct 19, 2012)

After putting in the ceramic insulation I have noticed the ash left is lighter and fluffier maybe an indication of a more complete burn.


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## BrotherBart (Oct 19, 2012)

If you ship 50,000+ stoves a year and have to pay the freight, try to get that sucker EPA certified with the lightest bricks you can find. And be the only place to buy replacements.  Kinda like Quadrafire with those with the holes drilled in them in the back.


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## Huntindog1 (Oct 20, 2012)

precaud said:


> I was intrigued by these coatings as well, but decided against experimenting with them. Here's why.
> 
> They all claim to work by reflecting infrared (that is wavelengths _longer_ than our visible spectrum). Look at them and you'll see they are all white in color, or nearly so. Their reflectivity is largely dependent on their color. If they were black, they would absorb visible and infrared. Inside the kilns in which they were designed to operate, they stay white, unless an accident happens.
> 
> ...


 

I thought I read someplace about a coating and it still working once it became dirty,  Its called Super Therm.

*Reflective Coating vs. Fiberglass vs. SUPERTHERM ®*
Manufacturers in the past have marketed "reflective" coatings by making claims that they continuously repel heat, and have specific "R" values. The problem with such claims is that these coatings only reflect visual light or short wave radiation, and when they become dirty they stop working completely. Once these claims proved false, all similar coatings were put into the same category and deemed non-viable.
*SUPER**THERM* ® was designed and developed with the assistance of NASA, a fact that can be substantiated. The "ceramic compound" blends found to work the best, and are now used in *SUPER**THERM* ®, resulted from 18 years of testing and research. The difference between the technology of "reflective" coatings of the past and *SUPER**THERM* ® today, is outlined below.
*SUPER**THERM* ® has the ability to block all the different radiation waves. *SUPER**THERM* ® not only blocks these waves when first applied, but continues to block them after the coating becomes dirty, which happens to all coatings. The ceramics used in *SUPER**THERM* ® were chosen from over 3,200 compounds, which were studied and tested in order to prove that they would block the different radiation waves the most effectively, producing the following results:
1. *SUPER**THERM* ® blocks *99%* of UV heat
2. *SUPER**THERM* ® blocks *92%* of Visual Light (short wave) heat
3. *SUPER**THERM* ® blocks *99%* of Infrared (long wave) heat
*This results in an average of over 96% of heat load blocked!*


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## rideau (Oct 20, 2012)

To add to Jags pondering, if there really is a significant difference in the insulative values of the different bricks, wouldn't the choice of bricks then affect necessary clearances? That doesn't seem to be the case....at least I've never heard of a MFG who cautioned against changing type of firebrick? Again, asking. I don't know.


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## rideau (Oct 20, 2012)

Where is Supertherm used?  An any standard firebricks?


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## ScotO (Oct 20, 2012)

I'm confused, fellas.  Isn't the whole point of having a woodstove in your home to put out heat?  I understand you want some reflectivity back into the stove to aid the secondaries and give you a good clean burn, but I want lots of heat out of the stove.  I installed regular firebrick in my Napoleon 1900 after burning out all the pumice brick, and it still has a very clean burn and great secondaries.....not to mention it stays hotter for longer periods of time.......Not bashing anyones scientific research, just trying to figure out why you want the majority of the heat in the stove, when I thought the point of efficiency was to get the majority of the heat OUT of the stove....


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## begreen (Oct 20, 2012)

> It still has a very clean burn


 
That's a subjective observation. The stove mfg. needs quantifiable and repeatable emissions reductions that are verified by a certified testing lab.


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## nate379 (Oct 20, 2012)

I have a mix in my stove.  I had to replace 7 or 8 bricks this summer when I cleaned it. (they were broken or broke when removing them!)

The replacements where the lightweight ones.  Was all the stove place had.


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## charly (Oct 20, 2012)

The Esse uses the light weight bricks and it states not to use the heavy bricks as the light weight bricks reflect the heat back into the firebox. For what it's worth. Woody talks about the firebrick. Sorry volume is low on the video. If you have speakers turn them up.


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## Huntindog1 (Oct 20, 2012)

I just like making people do the "What If Double Check" instead of the "Discount Double Check"

I think in these newer type stoves most the heat comes out the top and front. as they are lined with firebrick to insulate the fire box. What we are talking about here Is just taking it a little further and using an insulated brick instead of a not so insulated brick, they all are insulated. Its like going to Lowes and looking for the better R-Value in Fiber Glass insulation. With bricks there is a trade off in durablility. But I wanted to point out that in wood stoves there is more to insulative value due to the radiant heat that is the majority of the heat that a stove puts out. As its the radiant heat that allows the reflection factor to be a big factor in wood stoves. All bricks radiate heat back into the fire box just some can do it better. The ones with higher alumina content.

I also want to point out again even tho some may not agree, that if you can more easily maintain firebox temps , you then can more easily get your stove operating nicely at its lowest setting as most of the time I am working with my stove to get it set to its lowest setting that I can get but still maintain secondary burn. I already have the ceramic insulation in my stove behind the fire brick , instead of insulated fire brick, and the results are noticeable and I like the $30 tweak I made.

Too make this simple, in these secondaries type stove we all know from experience its all about the heat. We all know if you cant get the heat up in the stove , the stove doesnt perform as well, if you leave the door cracked it wont heat up for you. If your draft is too strong people have experience not being able to get the stove as hot as they would like, putting a manual draft damper in and slightly reducing draft mysteriously allows the stove to heat up a little more. Its all about the heat. Its the extra high heat in the fire box in these type stoves that allows the stove to burn more efficiently. 60 percent or more of the heat in wood is in the smoke gases. As you increase the temps the more efficient the stove burns more of the smoke gases. Thats how a wood gasifier boilers burn more efficient than a wood stove.


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## precaud (Oct 20, 2012)

Huntindog1 said:


> I thought I read someplace about a coating and it still working once it became dirty, Its called Super Therm.
> *SUPER**THERM* ® has the ability to block all the different radiation waves. *SUPER**THERM* ® not only blocks these waves when first applied, but continues to block them after the coating becomes dirty, which happens to all coatings.


Sure, it does a good job of blocking radiation that NEVER REACHES IT when it is dirty!


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## Huntindog1 (Oct 20, 2012)

precaud said:


> Sure, it does a good job of blocking radiation that NEVER REACHES IT when it is dirty!


 
Yep, its hard to believe their claims its almost magical. Only product I found to make that claim.


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## precaud (Oct 20, 2012)

Scotty Overkill said:


> I'm confused, fellas. Isn't the whole point of having a woodstove in your home to put out heat? I understand you want some reflectivity back into the stove to aid the secondaries and give you a good clean burn, but I want lots of heat out of the stove. I installed regular firebrick in my Napoleon 1900 after burning out all the pumice brick, and it still has a very clean burn and great secondaries.....not to mention it stays hotter for longer periods of time.......Not bashing anyones scientific research, just trying to figure out why you want the majority of the heat in the stove, when I thought the point of efficiency was to get the majority of the heat OUT of the stove....


I'm with you, Scotty. I want the most heat out of the stove. What confuses things is, in discussing this, different people use the same words with different meanings/connotations behind them. For example, efficiency. Is it measured by emissions? By wood consumed vs heat produced? By stove surface temps? By how long your stove "stays hot"?

I think the best measure of an EPA stove's ability to deliver the most heat is it's Firebox-Volume-to-Weight Ratio. Kinda like power-to-weight ratio that race car enthusiasts use. The higher the ratio, the more heat the stove will produce in a given period of time.

The most efficient stove is going to burn cleanly and then do a good job of extracting the generated heat as and when it is produced and getting it out into the room. What is described here is not a heat storage system. Storage inevitably involves energy loss, and the losses will be greater where the temperature differentials are the greatest (i.e. firebrick). So, instead of trying to store heat in the firebox lining, get it out into the room and have your "storage" there.

I have examples of this here. I have two clean-burning stoves, identical firebox sizes lined with IFB, one weighs 100 lbs less than the other. Guess which one delivers more heat into the room from one load to the next? There's no comparison. It's directly proportional to the weight difference.

If you're going to store heat in a stove, do it away from the firebox.


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## Huntindog1 (Oct 20, 2012)

I heard that there are some new wood smokers being designed that they replace firebricks with 3/4" plate steel as it has a higher density and higher mass.
Behind the 3/4" plate steel they are putting like 1" to 2" of Ceramic Koawool to cut the conduction down and provide the insulation needed to keep things hot. Would take longer to heat up like a soapstone.


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## precaud (Oct 20, 2012)

Yup. Good example. Not unlike using cast iron liners with kaowool backing aka Jotul. Keeps this "hotter, longer" but the stove never gets as hot as a proper insulating firebrick would allow it to. High firebox mass is like having a speed governor on a motor.


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## Huntindog1 (Oct 20, 2012)

Precuad, I see your rationale as if we can some how store the heat to radiate later when the stove flames out then we have heated our house better.

My idea maybe flawed but I only was thinking about extracting more btu's from using a hotter firebox. Especially at my stoves lowest setting. As If I can run my stove at a lower setting I get a longer burn. Again like i hoped at that lower setting and higher firebox temps I was hoping of getting more heat from the extra amount of smoke gases being burnt.due to a higher firebox temp.

But there is many ways to skin a cat, I like Precauds idea of once your wood gets to the coal stage to completely shut down all air flow in the stove and the coals will radiate heat over a much longer time period as it said that 20% of your heat goes up the flue and is wasted , well if you have the ability to shut off your secondary air and all of your primary airs then there is no air flow at all flushing the 20% of the heat up the flue. I should also state that once your at the coal stage creosote is no longer an issue as all of that stuff has been burnt out of the wood.


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## precaud (Oct 20, 2012)

Huntindog1 said:


> I only was thinking about extracting more btu's from using a hotter firebox. Especially at my stoves lowest setting. As If I can run my stove at a lower setting I get a longer burn. Again like i hoped at that lower setting and higher firebox temps I was hoping of getting more heat from the extra amount of smoke gases being burnt.due to a higher firebox temp.


 
There's no doubt that firebox insulation allows for more stable burns at lower rates. An insulated chimney helps there too.



> But there is many ways to skin a cat, I like Precauds idea of once your wood gets to the coal stage to completely shut down all air flow in the stove and the coals will radiate heat over a much longer time period as it said that 20% of your heat goes up the flue and is wasted , well if you have the ability to shut off your secondary air and all of your primary airs then there is no air flow at all flushing the 20% of the heat up the flue. I should also state that once your at the coal stage creosote is no longer an issue as all of that stuff has been burnt out of the wood.


 
I like the all-of-the-above strategy!


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## raybonz (Dec 2, 2012)

Anyone tried these? Just noticed a couple cracked firebrick in the back of the stove this morning when the fire lit.. I don't know the density of these bricks but the price is right!

http://www.tractorsupply.com/united-states-stove-single-firebrick-9-in--3112783

Ray


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## madison (Dec 2, 2012)

The ones I picked up at tractor supply, last yr, were at least 2 to three times heavier.  I have not used them yet, but have flipped some of the ones that have deteriorated....  none have cracked, just severely eaten away.


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## BrotherBart (Dec 2, 2012)

If the price is great you can bet that they are regular ceramic, not pumice, bricks.


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## FyreBug (Dec 3, 2012)

begreen said:


> The video is a sideline, not on topic. Lopi has a reputation of building tough stoves. Conventional firebrick is tougher. Lopi smartly is touting this as a feature, the same way SBI boasts the toughness of it's c-cast baffles. Good marketing but a bit off topic I think.


 
I think it's very much on point... If companies such as Lopi, SBI and others who have labs and the ability to measure material performances all day long do not see any performance advantages in using light weight bricks versus heavy duty bricks, it should tell you something... Especially in view of EPA tightening up their regulation for emissions and eventually efficiencies. 

If any MFG could prove better efficiencies, burn time, clean burn etc... with different bricks, do you not think they would 1) publish and brag about it with some real numbers 2) make sure they would only use that material?

We test and sell fireboxes with either bricks. We reserve the heavy duty bricks for our furnaces and our upscale brands for all the reasons mentioned previously and so does some other MFG's.


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## raybonz (Dec 3, 2012)

madison said:


> The ones I picked up at tractor supply, last yr, were at least 2 to three times heavier. I have not used them yet, but have flipped some of the ones that have deteriorated.... none have cracked, just severely eaten away.


I have a dumb question.. Do you have to remove the baffle to remove the bricks? The manual has no information about this..

Thanx,
Ray


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## madison (Dec 4, 2012)

No


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## velvetfoot (Dec 4, 2012)

My experience on the two quads I had led me to replace the pumice bricks with the heavier ones.  Not sure what I have now on the Hampton, but hopefully they will hold up better.  I believe I have an email somewhere from Quad, that said their bricks are good til half the thickness is worn away.  Half!  Geez.


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## raybonz (Dec 4, 2012)

madison said:


> No


Care to share how to remove and replace the back firebrick? BTW your stove and hearth look great! 

Thanx!

Ray


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## precaud (Dec 4, 2012)

FyreBug said:


> If any MFG could prove better efficiencies, burn time, clean burn etc... with different bricks, do you not think they would 1) publish and brag about it with some real numbers 2) make sure they would only use that material?


 
Actually, no I don't think they would. Not unless they could patent it and were prepared with the resources and legal staff to defend said patent world-wide. But choice of firebrick doesn't qualify. Better to just keep using it and not draw undue attention to it, like most manufacturers do...


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## raybonz (Dec 4, 2012)

BrotherBart said:


> If the price is great you can bet that they are regular ceramic, not pumice, bricks.


Yes they are not pumice and much heavier and harder too.. I am going to use these in the back of the stove as that is where 2 broken bricks are located.. I'll save the one good one for a spare for the bottom or sides.. I see nothing conclusive for or against using either brick type but I do feel the pumice bricks would be better insulators and based on this I want them on the bottom of the firebox..

Ray


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## madison (Dec 5, 2012)

raybonz said:


> Care to share how to remove and replace the back firebrick? BTW your stove and hearth look great!
> 
> Thanx!
> 
> Ray


Ray,

They slide and lift right out.  Wait for stove to cool.  Put on a pair of gloves. The cracked ones should be easy to remove, and will then allow the other vertical bricks to slide to either side to clear the retaining tabs.

And once you slide one of the bricks a bit to clear the retainer tab hanging off the baffle rails it will become obvious.   Just note that all of the bricks are not the same size. Note all of this is for the T6, T5 may be slightly different, but the general design should be similar.  Once you do it once, you will chuckle that you asked.


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## Huntindog1 (Dec 5, 2012)

If you want to keep using the insulative Pumice type bricks you can buy a product call ITC-100 that forge and brick oven operators already use.
This is a ceramic coating that increases the durability of the bricks. It is also said the ITC-100 reflects heat back into the box but thats a whole other can of worms. I used it for that purpose. I also coated my ceramic baffle boards to give them more durability.

http://digitalfire.com/4sight/education/refractory_coatings_offer_new_firing_possibilities_110.html

Here is a place to buy small quantities of ITC-100.

http://www.hightemptools.com/itcproducts.html


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## Huntindog1 (Dec 5, 2012)

Brick material and Thickness chart. You can look at this chart and see how the temps of the fire box are higher for Insulating firebrick and Alumina.

Higher the Alumina content the more heat radiation reflective it is. Reflecting the heat back into the fire box area. As the hot flue gases exit the stove heat is radiate out the front and top of the stove.

_*Mullite refractory:*_ Mullite brick is about 72% alumina with 28% silica. These have
excellent volume stability and strength at high temperatures. They are highly suitable
for electric furnace roofs, blast furnaces and blast furnaces stoves, and the superstructure of glass tank furnaces.


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## raybonz (Dec 5, 2012)

madison said:


> Ray,
> 
> They slide and lift right out. Wait for stove to cool. Put on a pair of gloves. The cracked ones should be easy to remove, and will then allow the other vertical bricks to slide to either side to clear the retaining tabs.
> 
> And once you slide one of the bricks a bit to clear the retainer tab hanging off the baffle rails it will become obvious. Just note that all of the bricks are not the same size. Note all of this is for the T6, T5 may be slightly different, but the general design should be similar. Once you do it once, you will chuckle that you asked.


Yup it was easy lol.. I did find that the TSC fire bricks are slightly wider and could not fit 2 side by side where I removed 2 side by side bricks so I moved the one good pumice brick beside a new ceramic fire brick. I will need to cut ~1/6" off the long side of one brick. Wish I still had the tile saw I borrowed when I did my hearth for this!

Ray


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## raybonz (Dec 5, 2012)

Huntindog1 said:


> Brick material and Thickness chart. You can look at this chart and see how the temps of the fire box are higher for Insulating firebrick and Alumina.
> 
> Higher the Alumina content the more heat radiation reflective it is. Reflecting the heat back into the fire box area. As the hot flue gases exit the stove heat is radiate out the front and top of the stove.
> 
> ...


Thanx for posting Hdog but for right now I will try it out as is. These new bricks are quick dense and heavy and much whiter so they may be better at reflecting heat. I will find out very soon and report what I see..

Ray


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## raybonz (Dec 5, 2012)

Just fired up the stove 2 of the heavy firebricks and noticed nothing different..

Ray


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## Greek2Me (Jan 23, 2015)

Huntindog1 said:


> I thought I read someplace about a coating and it still working once it became dirty,  Its called Super Therm.
> 
> *Reflective Coating vs. Fiberglass vs. SUPERTHERM ®*
> Manufacturers in the past have marketed "reflective" coatings by making claims that they continuously repel heat, and have specific "R" values. The problem with such claims is that these coatings only reflect visual light or short wave radiation, and when they become dirty they stop working completely. Once these claims proved false, all similar coatings were put into the same category and deemed non-viable.
> ...



_______________________________________________________________________________________________

Before you invest ANY money in this product, you should check out this article.  It made my decision easy!  

http://www.greenbuildingadvisor.com...lating-paint-salesman-tripped-his-own-product

Maranatha

Greek2Me


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## begreen (Jan 23, 2015)

3 yr old thread. Closing.


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