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

[HotCoals]

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.

 

[bholler]

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.

 

[Benchwrench]

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.

 

[Benchwrench]

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

 

[northwinds]

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.

 

[mellow]

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.