Fire brick question

Hi - I need to replace fire bricks in my wood burner. The existing ones covered just the side walls. I’ve subsequently seen that the burners are best with fire bricks all around but my burner is a funny shape and the ones I bought don’t fit exactly. Photo attached. Is what I’ve done ok / safe? The burner is built in. Thanks

Hi Simon, and welcome to permies!

The instructions for my fire say to keep a layer of ashes in the bottom and that works fine. Only the top baffle needs replacing from time to time, but I got almost 10 years out of the first one by slapping some fireclay on it when it started eroding in the middle.

Hi Phil - thanks for the welcome and the advice! Does it matter that I don’t have complete coverage with firebrick throughout the rest of the burner? Thanks

Hi Simon,   For the most part, any exposed metal in the firebox will deteriorate faster if it is not protected by the firebricks. The top baffle is the one exception. A lot of newer stoves actually have baffles made from firebrick though. So it really depends on whether or not you want to keep this stove for many more years or just want to get by for now. Not sure how the brick arrangement was before but you could also add more by cutting those bricks you have to make them fit more closely together as well.
A wet saw, grinder with a masonry cutoff wheel or diamond blade all can work.

Great - thanks Gerry.

I think the gap could be filled with sand as an alternative.  My stove came with a suggestion of sand on the floor - about 1".

I think it's really important to have full coverage that's equivalent to your original bricks.

It's more than simple wear and tear on the exposed bits. A gap would encourage differential heating, with the possible risk of warping the metal.

Can you break small chunks off of the original bricks and stuff them in there with clay or stove cement? That would be close enough, and ash will seal up the tiny cracks.

Edit: I think Gerry was suggesting essentially the same thing. So, full credit given.

I agree with the differential heating idea, With gaps in the bricks you are asking those bits of exposed metal to radiate more heat than the covered sections, those bits will also cool faster possibly causing warping or cracking.

Clay is a real easy effective alternative, use the bricks where they will receive the rough treatment of wood being shoved around, and mold the clay in places where it's  receives less  rough treatment.

The nice thing about the clay is it's easily replaced or repaired,