# Firebrick - Pumice (lightweight) vs. standard (heavier)



## Benchwrench (Jun 3, 2014)

It's time for me to replace some firebrick. Mainly due from me poking at them at the back of the firebox with a sharp poker!
The OEM brick is made of pumice which is much lighter than what is found locally such as clay Rutland firebrick.

Can anyone tell me why I should to use one over the other?
Is there that big of a difference between using readily available heavier clay firebrick over harder to find pumice firebrick?

Our local Rural King has the heavier Clay type firebrick for $1.80 each



Thank you guys for your input.


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## begreen (Jun 3, 2014)

If you only need a couple bricks I would get the pumice brick. It has greater insulation value for a bit hotter fire. You can buy the pumice brick online if not available locally. FWIW, my poker is shaped like an "L" at the tip for the last 2". That may be helping me not to poke the firebrick.


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## Huntindog1 (Jun 3, 2014)

Pumice is less durable but more insulative , standard bricks are more durable but less insulative.

You cant always find specifications for fire bricks, but some have higher alumina content which I think gives them more reflective properties.

Which heat reflection is a biggy as most the heat in the fire box is radiated heat which can be reflected back into the box. Thats how they make these stoves more efficient by keeping the heat up in the firebox to higher levels.

As Begreen knows I at one time put ceramic insulation behind my fire bricks. The stove had a noticeable improvement in ease of operation but I think it was less able to radiate heat out into the room.

Long story short I recently got a new stove that has a fire box not well insulated  but I love the extra amount of radiated heat out of the stove I get even when just hot coals in the stove. The emissions and efficiency ratings suffer on my new stove but the extra heat  radiated makes me happy.

So there is a little insight on insulative fire brick idea verses non-insulative fire brick.

And Begreen I know you told me so. LOL

Our old friend OldSpark broke down and got the same stove I did and he loves it too. He noticed the extra amount of radiated heat into the room which is what he was looking for.


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## Benchwrench (Jun 3, 2014)

Thanks, just did another search on the topic. It looks like I'll have to do a bit more looking around locally for pumice since that's what comes with the stove.


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## begreen (Jun 3, 2014)

> Our old friend OldSpark broke down and got the same stove I did and he loves it too. He noticed the extra amount of radiated heat into the room which is what he was looking for.



I told him the second season to take off the side panels of the Summit. He never did and instead griped endlessly about the stove flue temps when what he actually wanted was a radiant instead of a convective stove.


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## begreen (Jun 3, 2014)

Benchwrench said:


> Thanks, just did another search on the topic. It looks like I'll have to do a bit more looking around locally for pumice since that's what comes with the stove.



http://www.stoveworld.com/Pumice-Firebrick-Splits-6-Pack-p/2rpala999.htm
http://www.amazon.com/QuadraFire-Pumice-Bricks-832-3040-Uncut/dp/B00AWS3HQO


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## BCC_Burner (Jun 3, 2014)

Hmm, anyone tried the Pumica bricks in an NC-30?  I can't imagine you would lose much radiant heat if any, as the stove isn't fully lined, but perhaps a more complete burn front to back with higher temps in the firebox?


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## begreen (Jun 3, 2014)

The 30NC is an exceptionally clean burning stove already. I wouldn't bother.


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## BCC_Burner (Jun 3, 2014)

It definitely is, I'm thrilled with the stove the way it is.  Just thinking of little things I can do to improve the cleanliness and efficiency given my very short chimney.


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## mellow (Jun 3, 2014)

Unless it has been tested with the pumice bricks I wouldn't bother switching, just another expense that would take a while to get ROI if you could ever figure out IF you got ROI out of it. 

I am a fan of the heavier bricks, just not moving or shipping them.


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## Benchwrench (Jun 3, 2014)

I have about 26 regular type firebrick on hand in an attempt to pre-plan and stock up to replace the damaged ones inside the firebox, not realizing there was such a thing as "pumice" firebrick
Oh well such is life... 
I guess I'll have to sell these 26 and get the OEM pumice type .
Finally will get my money's worth using Flat rate shipping boxes!


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## Benchwrench (Jun 3, 2014)

Thanks you guys for the info and BeGreen for the links


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## Benchwrench (Jun 4, 2014)

Also...
found out there is such a thing as insulative firebrick mainly made mainly of ceramic properties.  This type are also sold locally and more available than pumice.
With the pumice, It's hard for me to rationally plink down nearly 50 bucks for 6 bricks!


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## HotCoals (Jun 4, 2014)

Huntindog1 said:


> Long story short I recently got a new stove that has a fire box not well insulated but I love the extra amount of radiated heat out of the stove I get even when just hot coals in the stove. The emissions and efficiency ratings suffer on my new stove but the extra heat radiated makes me happy.



Would you also agree that if you had a cast jacket wrapped around your stove or flat stone glued to it that either of those would cut back on radiated heat to the room?


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## bholler (Jun 4, 2014)

I agree that a cast wrap reduces radiant heat but if the stone is glued to the metal it would still radiate just fine.  It would take longer to heat and start radiating but still would radiate as well.  That being said i have never seen a stove with stone glued to the outside the ones i have seen are either made of stone or stone jacketed basically.  Are there ones with stone glued to the outside?  sounds like a nice idea if it would work.


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## HotCoals (Jun 4, 2014)

bholler said:


> I agree that a cast wrap reduces radiant heat but if the stone is glued to the metal it would still radiate just fine.  It would take longer to heat and start radiating but still would radiate as well.  That being said i have never seen a stove with stone glued to the outside the ones i have seen are either made of stone or stone jacketed basically. * Are there ones with stone glued to the outside?*  sounds like a nice idea if it would work.



I just put it in to words that way...my bad really.
Though I know one guy who was thinking of putting ceramic tile on his,don't know if he ever did.
I'm of the mindset that anything like that slows the transfer rate down. I don't think anybody can change my stubborn dutch thinking either..lol.


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## bholler (Jun 4, 2014)

I just dont know what you could use to glue it on with that would hold up to the heat and be flexible enough to allow for the difference in expansion rates.  I prefer a slower more even heat personally but that is all about personal preference


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## begreen (Jun 4, 2014)

In many installs, slowing down the radiant heat is a good thing. A lot of radiant stoves had to be crossed off the list for our corner install due to clearances. I really like the soft heat from the cast iron jacket and they definitely help even out room temperature swing over the course of a burn. But for others a strongly radiant stove is perfect for their installation and needs.


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## begreen (Jun 4, 2014)

bholler said:


> I just dont know what you could use to glue it on with that would hold up to the heat and be flexible enough to allow for the difference in expansion rates.  I prefer a slower more even heat personally but that is all about personal preference


Any tiled or stone clad steel stove that I have seen have the tiles held captive but loose in a frame to allow for the difference in expansion rates.


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## HotCoals (Jun 4, 2014)

bholler said:


> I just dont know what you could use to glue it on with that would hold up to the heat and be flexible enough to allow for the difference in expansion rates.  I prefer a slower more even heat personally but that is all about personal preference


Yeah on the first part.
On the second part that sounds counter productive to me. Again,the stubborn Dutchman in me.
My cat stove does give time timed released heat ,way more uniform then my bbk non-cat did.
Cheers!


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## bholler (Jun 4, 2014)

begreen said:


> Any tiled or stone clad steel stove that I have seen have the tiles held captive but loose in a frame to allow for the difference in expansion rates.


yeah same here


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## HotCoals (Jun 4, 2014)

begreen said:


> Any tiled or stone clad steel stove that I have seen have the tiles held captive but loose in a frame to allow for the difference in expansion rates.


That makes sense.
I should find out how that guy made out if in fact he did "glue" tile to his stove.


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## bholler (Jun 4, 2014)

i don't see it as counter productive at all all that heat comes off the stove eventually it just tempers the normal fluctuations.


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## HotCoals (Jun 4, 2014)

bholler said:


> i don't see it as counter productive at all all that heat comes off the stove eventually it just tempers the normal fluctuations.



Well in my stubborn mind the more insulated the stove is to the area to be heated , the more heat that will travel up the flue instead of getting transferred to the room.
Let me ask you this. Take my stove,burn some wood..then make all the surfaces a foot thick and burn another fire the same size.Which way would I have gotten the most btu's into my house?

My thought is with my stove as it is not with foot thick walls.
Maybe you will say the stove with the thick foot walls will "bank" the heat that I lost heating up the thick walls. I say I don't think so..it will bank some heat no doubt but overall I think I lost more up the flue then what the foot thick walls banked..lol.

I know..I know I should not think so hard..lol.


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## begreen (Jun 4, 2014)

It's not insulated. There is an airgap between the stove and the cast (or steel) cladding that convects quite nicely. The radiant energy is the same it's just absorbed by the shell.


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## HotCoals (Jun 4, 2014)

begreen said:


> It's not insulated. There is an airgap between the stove and the cast (or steel) cladding that convects quite nicely. The radiant energy is the same it's just absorbed by the shell.



That also makes some sense. Convection is also happening you would think,as you said.


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## bholler (Jun 4, 2014)

Yes if there is a gap between the 2 materials you will loose some of the radiant heat as convective heat and if they are solid or at least tight the heat will be absorbed and slowly radiated through the walls and into the room.  Now back to the original question about the brick.  Yes the pumice brick that come with many new stove do insulate the fire box reducing radiant heat in the areas covered by those brick.  This does 2 things it keeps the fire box temps higher where the manufacturer wants them higher and directs the heat where they want it to go.  It also helps to reduce clearances along with the shielding that is on the outside of many new stoves.  With regular fire brick technically those manufacturers clearances no longer apply.


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## Benchwrench (Jun 11, 2014)

my local fireplace dealer doesn't  stock insulative brick, just the regular fireclay type. 
You guys' rational (as noted above) seems on par with how I originally though about just using heavy firebrick, more heat transfer to the stove but I didn't want to re-engineer anything, besides it's still under warranty. But they don't cover replacement bricks. 
I'm not an appliance engineer but after doing a good search I came up empty handed as to why this manufacture chose to uses pumice in it's stove design.
Maybe later on I'll see the light and use regular ol' fireclay bricks like everyone else.


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## Benchwrench (Jun 12, 2014)

We're only talking about 1.25" of firebrick insulation, I can't imagine there being THAT much difference between the types.
I think the main reason this manufacturer went with pumice brick is to possibly gain fewer emissions, other than that, I don't see much rationale


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## northwinds (Jun 12, 2014)

Benchwrench said:


> We're only talking about 1.25" of firebrick insulation, I can't imagine there being THAT much difference between the types.
> I think the main reason this manufacturer went with pumice brick is to possibly gain fewer emissions, other than that, I don't see much rationale



It's not what you imagine.  It's what your dealer or insurance company might imagine if warranty or clearance issues come into play.  Other than that, you're probably right.


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## mellow (Jun 12, 2014)

Quadrafire was approached by the company that makes the pumice bricks and made a deal they couldn't refuse.   <--- In my mind that is how it went down, they buy said pumice brick for $1.00 and resell for $6.00.


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