Types of Firebrick

[wg_bent]

Today I stopped by the local stove dealer, and bought 2 new bricks for my Osburn. The originals had gotten these odd klinker type things stuck to the brick, then the brick basically just fell apart. The original brick looked a lot like a cinder block type material, and the new looked more like a concrete paver with a little yellow color. The new brick was clearly a much denser material. Is this a problem? Will the new brick perform o.k.? Gut feel tells me that the new brick is a better quality brick, since it's a LOT heavier. Probably twice as heavy. Bricks were 5 bucks a peice Is this possibly why an Osburn is cheaper than other stoves?

I'm thinking of replacing all the bricks in the stove now, anyone think I should?

I feel a picture coming on! will post later if I get the chance.

 

[MountainStoveGuy]

I believe you bought the ceramic style instead of the pumice style. I believe the ceramic style is better. They should last longer as long as you dont hit em to hard loading the stove.

 

[wg_bent]

I only replaced the center two, should I replace the other two on the bottom of the stove to be consistant?

 

[Shane]

I wouldn't worry about it. I think the pumice style transfer heat more rapidly and the denser ones retain heat longer.

 

[Martin Strand III]

Warren:

Your question involves the rather large subject of refractory materials; those materials having the ability to withstand heat.

The whitish bricks found in linings of metal stove fireboxes are usually a type of firebrick which has fewer impurities giving it a higher melting point and ability to withstand higher temperatures than the ordinary reddish clay brick, an example of an ordinary fired clay brick. The red color of common brick comes from iron and other impurities (like lime) in the clay which lower the melting point.

Another whitish or concrete looking brick could be what is called a castable refractory unit which amounts to high temperature concrete. Here calcium aluminate cement is substituted for portland cement (binders) that is mixed with sand and gravel (aggregates) and hardens by chemical reaction like ordinary concrete. Bricks, and firebricks, harden by being fired at high temperatures in a kiln. BIG difference. You don't want any concrete to line your firebox.

Nor do you need the super-duper heavy duty industrial strength firebrick to line your firebox since even the lowest rated brick is able to withstand temperatures much higher than it would ever be subject to in a woodstove firebox. Firebrick is intended to be heated to high temperatures and KEPT THERE. Here's the problem: any woodburning firebox does not maintain a constant high temperature. It cycles hot-cool-hot-cool; called thermal cycling and, with more extreme or rapid heating-cooling, called thermal shock. Both are a major enemy to hot brick/firebrick resulting in cracking and deteriation of the material.

Therefore, it is not unusual to have to replace firebricks in a stove firebox. Brick units are great for what they were intended (not our applications) but we ask them to do too much.

If it were me, I would use any cheap brick and then treat it right: slow heat ups and cool downs and not throw more logs in the firebox while reloading your stove like you were an artillery gunner shoving a new shell in the breach of a big gun (aka TLC).

Aye,
Marty

 

[elkimmeg]

What I have done is take ordinary clay fire bricks and cut them in a wet saw to the 1" thickness, you can get to to ever brick